Original Link: http://www.anandtech.com/show/2270



One of the first coolers evaluated at AnandTech was a combination of air cooling and TEC (Thermal Electric Cooling) called the Vigor Monsoon II. The Monsoon did very well in overclocking, and is still the highest overclocking cooler we have tested, reaching 3.96GHz with the standard Core 2 Duo X6800 in our OC tests. While the Monsoon did very well in overclocking it did have a higher noise level than we care for, the result of the TEC switching on and off coupled to a fan that buzzed as it was turned on and off with the TEC. Since then we have reached 3.90 to 3.94GHz with several of the top air coolers, but we have not looked at more hybrid coolers - until today.

Several new "self-contained" water coolers have shown up over the past few months. Water cooling is another ambient cooling method, like air cooling. The water temperature cannot drop lower than the room temperature, where TEC and phase-change can actually chill below the ambient temperature. This is why they are referred to as sub-ambient cooling. Water cooling is normally considered superior to air cooling because water can normally hold low temperatures for a longer period of time than air. Water is a much better thermal conductor than air and it is theoretically a better cooling vehicle.

There are many high-end water cooling solutions with water-filled tubing that runs from CPU blocks to radiators for cooling and reservoirs for storage, and pumps for moving the liquid. The water systems are usually complicated, somewhat difficult to install, and plagued with the fact that water and electricity don't play well together, so a leak can destroy a computer system. This is where "self-contained" comes in. The water system is sealed, and the radiator, pump, fan, heatpipes, and fins are all together in a package about the size of a heatpipe tower.


This is clearly illustrated in the Xigmatek AIO (All-In-One) which contains finned water-cooled heatpipes, an internal fan, and a pump and radiator in a package about the size of a heatpipe tower.


The Evercool Silver Knight, or WC-601, is based on a similar concept, but with an external water pump and fan, instead of the internal units as used on the Xigmatek. The Evercool is a bigger self-contained water system, but it still had no problem fitting our tight EVGA 680i motherboard.

The idea of the self-contained water cooling is to make water cooling simpler. These two units cannot even be recognized as water cooling systems. They mount just like a heatpipe tower and are a one-piece, no-maintenance, no-risk water cooling system. That concept is certainly intriguing, but the larger question is whether these new self-contained water coolers can give the best air coolers a run for their money. We will find out if they can in our comparison to the top air coolers tested at AnandTech.

Water cooling is also well known for the low noise levels exhibited by many of the better water cooling systems. Are these self-contained water systems as quiet as they claim to be? With these questions in mind let's take a closer look at these two all-in-one water coolers.



Evercool Silver Knight

Evercool is a Top 5 Cooling Products manufacturer based in Taiwan. Manufacturing is at their facility in Guang Dong, China. The Evercool product line consists of air and water coolers for processors and video cards, fans, hard drive coolers, notebook chill pads, system cooling solutions, and peripheral cooling specialty items. The company was founded in 1992 in Taipei. Evercool opened the China manufacturing plant in 1997. Today Evercool employs 1200 at its Taipei R&D facility and its Guang Dong ISO9001 manufacturing plant.

The Silver Knight was first shown at CES this year and today it can be found for sale at many web etailers such as Newegg. The Silver Knight was originally introduced at a retail price of $59.95. A quick check of the web found it available $45 to $50 from several etailers. This is certainly competitive with the top-line air coolers.


Judging from the size of the silver, black, and red Silver Knight package, you would never guess this is a water cooling system. More correctly it is a hybrid water and air cooling system about the size of a heatsink tower.


Inside the box is a ready-to-mount Silver Knight system, along with the mounting accessories for mounting on an Intel socket 775 or an AMD socket 754/939/940. We also tried the clip on several AM2 boards. The clip is a triple lug design that fits fine on recent flat side AM2 mounting cages. However some AM2 mounts have curved sides and these might require some modification to the clip for proper mounting. Evercool also includes a small syringe of thermal compound. Installation instructions are on the box and prominently displayed at the Evercool website.


The Silver Knight cooler is rather strange looking. The knight's "helmet" top looks more like an alien space ship than a helmet to us. While the cooling core is 8mm copper pipes and aluminum cooling fins, much of the shroud, fan, pump, and cover are plastic.


The standard size 92mm fan blows air through the cooler much like other heatpipe towers, and the 12-pole magnetic pump with a clear housing on the side circulates an antifreeze-like liquid through the 8mm copper pipes. Consider this a heatpipe tower with active circulation for the heatpipes. The clear plastic reservoir and motor on the side glow a soft blue during operation of the Silver Knight.

Mounting is simple and very secure with either 775 or AMD. However, you will have to remove the motherboard and mount the cooler to the motherboard before remounting the motherboard. The hex wrench included for tightening screws barely fits between the cooler top and the screws. It's a tight fit, but not impossible. We ended up hand-tightening the spring screws first and using the hex for the final tightening. The installation is solid and cannot be moved around. That is very good since the cooler weighs in at 960g, which is over 2 pounds.


On AMD the Silver Knight is ready for attaching with an included AMD clip. On the 775 you must first screw on two plates to extend the footprint of the Evercool.


A bottom plate with long attached screws passes through the motherboard, the cooler is placed on the screws, and the cooler is held in place with spring-loaded screws. The completed install is very stable.

Specifications

Our test system is Intel socket 775, but the Silver Knight will also mount on any recent AMD socket as well. While the manufacturer only specifies AMD socket 754/939/940 compatibility, we had no problem installing the cooler on socket AM2 with recent mounts that feature flat sides and a single connecting lug on each side. The Evercool kit includes the clip for mounting to existing AMD sockets, and the back plate, adapter plates, and spring-loaded screws for an Intel socket 775 install.

Evercool Silver Knight Specifications
Heatsink
Dimensions 130(W) X 126.5(D) X 185(H)mm
Weight 960g
Material Copper Base and Aluminum Fins
Heatpipes 8mm copper heatpipes
Water Pump 12-pole Magnetic Motor
Water System Refillable, should not require refilling for at least 2 years
Rated Voltage DC 12V
Fan
Fan Size 92 x92x 25mm
Bearing Type Ever Lubricate Bearing
Connector 3-pin with integral High-Low Switch
Speed Lo Speed 1,800rpm Hi Speed 2,600rpm

The Evercool appears to be a very large cooler, but the water pump and fan overhang at a higher level than many heatpipe towers. This makes mounting much easier than you might expect. The Silver Knight cleared all components on our test EVGA 680i. The EVGA 680i is a difficult to fit board due to the copper-finned heatsink and fan cooling the Northbridge. Installation was also an easy task on the ASUS Striker and ASUS Commando, and on the two new P35 ASUS boards - the P5K Deluxe and P5K3 Deluxe.



Xigmatek AIO

Xigmatek Co., Ltd. is a new name in thermal products, It is a Taiwan company affiliated with the Xinruilian Science & Technology Co. Ltd., located out of China. This company is one of the largest fan and PC power supply makers in the world and produces the well-known X-Fan line of PC system fans. There are six founders and one major investor in Xigmatek - all of whom have many years of direct experience in the PC cooler industry. More information about Xigmatek and the company's product line is available at the Xigmatek website.

Xigmatek is currently entering the US market, which is why the products will likely be unfamiliar to US readers. However, the company currently distributes products through primary distributors in Germany and Japan, and the products are available throughout Asia. While final pricing of the AIO will be set by the US distributor, MSRP is $69.95 with a likely street price of the Xigmatek AIO of around $60.


As the Xigmatek package proclaims, this self-contained water cooler is the AIO, or All-In-One, with an official model number of the AIO-S800P. The 800 in this case likely refers to the 80mm fan used in the design, and the P perhaps refers to "parallel" since the Xigmatek uses a pair of radiators for liquid cooling.


Inside the box is a ready-to-mount AIO, the mounting accessories for mounting the AIO on an Intel socket 775 or socket 478, and the mounts for AMD socket 754/939/940 and AM2. Xigmatek also includes an installation guide, two power converters for the fan headers to Molex connectors, and a packet of thermal grease. Everything in the package is protected by an inner plastic clamshell. Our sample was well-protected during shipping and had no visible damage when we unpacked the cooler.


If the Xigmatek looks to you like an old-time car radiator, there is a reason for that. Xigmatek has combined a bottom reservoir, just above the copper mounting plate, with a super quiet 12V pump in the reservoir area. This delivers liquid to the two radiators - one on each end of the tower - with an 80mm fan sandwiched in-between for cooling. Unique to the Xigmatek design is that no water pipes are used and water continues to cirulate even when the system is off. Xigmatel claims this design provides the least resistance to the flow of water into the radiator, which delivers an impressive 72 L/hr flow from a small 80mm design.


There are two fan connectors. One is a standard 3-pin for the water pump. If you are more comfortable this connector can be driven by an included Molex connector - useful for boards with anemic fan header wattage. There is also a standard Intel 4-pin fan connector for the variable fan speed, and an included adapter to Molex for those who prefer that route. We connected the 4-pin to the Intel header and the 3-pin to the Molex adapter for safety and experienced no problems during our testing.


Air-flow direction is indicated by an arrow on the top of the cooler, and the arrow should generally be pointed toward the back of the case, an exhaust vent, or a case fan. You can also see the cap for refilling the water system if needed. It is covered with "Warranty Void" tape, however, to reflect the fact that Xigmatek specifies a useful life of 30,000 hours before any refilling or topping off of the liquid is required.

Mounting is simple and reasonably secure with either 775 or AMD. The cooler mounts to a mounting cage (AMD) or adapters (775) that are screwed to the motherboard. The cooler rests on the mounting cage and is secured by four spring-loaded screws. You will need to remove the motherboard for mounting the AIO, but it is otherwise a fairly painless install.

The AMD/AM2 install is the more secure since it uses a complete rigid cage for mounting the cooler. The Intel install uses half-adapters molded from rigid plastic. The adapters seem rigid enough, but the half-adapter design allows a fair amount of flexing on the socket 775 motherboard used to test the Xigmatek AIO. The complete cage used for the AMD/AM2 install appears to provide better support for the 840g self-contained water cooling system.

Our sincere thanks to Frozen CPU and Xigmatek for arranging a retail review sample of the AIO.

Specifications

Our test system is Intel socket 775, but the AIO will mount on any recent AMD socket as well - including 754/939/940 and AM2. The Xigmatek kit includes the cage and spring-loaded screws for AMD processors. All the needed hardware is included, and installation is very easy on AMD/AM2 sockets once the motherboard is removed from the case.

Xigmatek AIO Specifications
Heatsink
Dimensions 114(W) X 121(D) X 127(H)mm
Weight 840g
Material Copper Base and dual corrugated Aluminum Fin radiators
Water Block Copper 70x54x14
Radiators Two Aluminum 80x88.7x22mm
Water System Refillable, should not require refilling for at least 30,000 hours
Rated Voltage DC 12V
Pump
Voltage/Input Current 12V/0.3A
Speed 3500rpm
Water Flow 72 L/hr
Bearing Type Ceramic Shaft
Life Expectancy 50,000 hours
Noise Level 19dBA
Fan
Fan Size 80x80x25mm
Bearing Type Ball Bearing
Fan Life 50,000 hours
Connector 4-pin (Intel 4-pin, PWM Ready) Variable Speed
Thermal Resistance 0.21-0.35C/W
Speed Lo Speed 1,800rpm Hi Speed 3,500rpm
Noise Level Lo Speed 20dBA Hi Speed 32dBA
Fan Output Lo Speed 27.88cfm Hi Speed 52.72cfm
Air Pressure Lo Speed 1.84mmH2O Hi Speed 5.56mmH2O

The Xigmatek is relatively small compared to heatpipe towers. This is mostly because it is based on an 80mm fan and 80mm radiators. At 127mm high it should fit in most cases. You will need to check on the clearances for HTPC cases. The test bed EVGA 680i is a difficult to fit board due to the copper-finned heatsink and fan cooling the Northbridge. The AIO fit comfortably on the 680i. Installation was also an easy task on the ASUS Striker and ASUS Commando, and on the two new P35 ASUS boards - the P5K Deluxe and P5K3 Deluxe. The P5K3 Deluxe is another "difficult-fit" board since the heatpipes completely circle the CPU socket and connect various cooling heatsinks around the CPU socket.



CPU Cooling Test Configuration

The standard test bed for cooling tests is the EVGA NVIDIA 680i SLI motherboard. This is primarily based on the consistent test results on this board and the NVIDIA Monitor temperature measurement utility, which is part of the nTune program.


NVIDIA Monitor has a drop-down pane for temperature measurement which reports CPU, System, and GPU measurement. At this point reviews will concentrate on CPU temperature. In addition to the real-time temperature measurement, NVIDIA Monitor also has a logging feature which can record temperature in a file in standard increments (we selected every 4 seconds). This allows recording of temperatures during testing, which can then be reviewed when the stress tests are completed. There is also the handy reference of speeds and voltages in the top pane to confirm setup.

NVIDIA Monitor was compared to test results from the Intel TAT (Thermal Analysis Tool). Intel TAT CPU portions do function properly on the EVGA 680i motherboard, but the chipset-specific features do not operate as they should. Idle temperatures in TAT were in line with measured idle temps with NVIDIA Monitor. The CPU stress testing with TAT pushing both cores showed TAT stress temps at 80% CPU usage roughly corresponded to temps reported in our real-world gaming benchmark.

Other components in the cooling test bed are generally the same as those used in our motherboard and memory test bed:

Cooling Performance Test Configuration
Processor Intel Core 2 Duo X6800
(x2, 2.93GHz, 4MB Unified Cache)
RAM 2x1GB Corsair Dominator PC2-8888 (DDR2-1111)
Hard Drive(s) Hitachi 250GB SATA2 enabled (16MB Buffer)
Video Card: 1 x EVGA 7900GTX - All Standard Tests
Platform Drivers: NVIDIA 9.53
NVIDIA nTune: 5.05.22.00 (1/16/2007)
Video Drivers: NVIDIA 93.71
CPU Cooling: Xigmatek AIO (AIO-S800P)
Evercool Silver Knight (WC-601)
Enzotech Ultra-X
3RSystem iCEAGE
Thermaltake Big Typhoon VX
Thermaltake MaxOrb
Scythe Andy Samurai Master
Cooler Master Gemini II
Noctua NH-U12F
ASUS Silent Square Pro
Scythe Ninja Plus Rev. B
OCZ Vindicator
Thermalright Ultra 120 Extreme
Thermalright Ultra 120
Scythe Infinity
Zalman CNS9700
Zalman CNS9500
Cooler Master Hyper 6+
Vigor Monsoon II Lite
Thermalright MST-9775
Scythe Katana
Tuniq Tower 120
Intel Stock HSF for X6800
Power Supply: OCZ PowerStream 520W
Motherboards: EVGA nForce 680i SLI (NVIDIA 680i)
Operating System(s): Windows XP Professional SP2
BIOS Award P26 (1/12/2007)

All cooling tests are run with the components mounted in a standard mid-tower case. The idle and stress temperature tests are run with the case closed and standing as it would in most home setups. We do not use auxiliary fans in the test cooling case, except for the Northbridge fan attached to the 680i for overclocking. Room temperature is measured before beginning the cooler tests and is maintained in the 20 to 22C (68 to 72F) range for all testing.

Evercool provided a small syringe of premium thermal grease with the Silver Knight, while Xigmatek provided a packet of standard thermal compound. We tested both self-contained water cooling systems with our standard premium silver-colored thermal compound. In our experience the thermal compound used makes little to no difference in cooling test results. This is particularly true now that processors ship with a large manufacturer-installed heatspreader. Our current test procedure uses this standard high-quality silver-colored thermal paste for all cooler reviews.

We test the stock Intel cooler at standard X6800 speed, measuring the CPU temperature at idle and while the CPU is being stressed. The CPU is stressed by running continuous loops of the Far Cry River demo. The same tests are repeated at the highest stable overclock we can achieve with the stock cooler. Stable in this case means the ability to handle our Far Cry looping for at least 30 minutes.

The same benchmarks are then run on the cooler under test at stock, highest stock cooler OC speed (3.73GHz), and the highest OC that can be achieved in the same setup with the cooler being tested. This allows measurement of the cooling efficiency of the test unit compared to stock and the improvement in overclocking capabilities, if any, from using the test cooler.

Noise Levels

In addition to cooling efficiency and overclocking abilities, users shopping for CPU cooling solutions may also be interested in the noise levels of the cooling devices they are considering. Noise levels are measured with the case on its side using a C.E.M. DT-8850 Sound Level meter.

This meter allows accurate sound level measurements from 35bdB to 130dB with a resolution of 0.1dB and an accuracy of 1.5dB. This is sufficient for our needs in these tests, as measurement starts at the level of a relatively quiet room. Our own test room, with all computers and fans turned off, has a room noise level of 36.4dB.

Procedures for measuring cooling system noise are described on page 6 which reports measured noise results comparing the stock Intel cooler and recently tested CPU coolers to the Evercool Silver Knight and Xigmatek AIO.



Cooling at Stock Speed

Some users will never overclock their CPU, but they still want to run the coolest CPU temperatures possible to enhance stability and extend CPU life. We tested the Xigmatek AIO and Evercool Silver Knight coolers with the supplied fans.

X6800 Stock (2933MHz) IDLE Temperature

Where the Intel stock cooler keeps the X6800 at 41C at idle, the Xigmatek manages 31C and the Evercool 34C. Both results are a significant improvement over the Intel stock cooler performance, but the results are average at best among the coolers tested at AnandTech. The Thermalright coolers, at the top of our heatpipe tower performance charts, cool to 26C and 27C, and the Tuniq 120 maintains 27C.

It is more difficult to effectively simulate a computer being stressed by all of the conditions it might be exposed to in different operating environments. For most home users CPU power is most taxed with contemporary gaming. Therefore our stress test simulates playing a demanding game.

The Far Cry River demo is looped for 30 minutes and the CPU temperature is captured at 4 second intervals with the NVIDIA Monitor "logging" option. The highest temperature during the load test is then reported. Momentary spikes are ignored, as we report a sustained high-level temp that you would expect to find in this recording configuration. This test configuration roughly equates to an 80% CPU load test using Intel TAT.

Cooling efficiency of the Xigmatek AIO and Evercool Silver Knight are compared under load conditions at stock speed to the retail HSF and other recently tested CPU coolers.

X6800 Stock (2933MHz) LOAD Temperature

The stock load test results are very interesting, not so much from a performance standpoint as in revealing how the two self-contained water coolers operate. The Xigmatek, best at idle, goes to 52C at load, indicating the auto fan has not kicked into higher RPM mode at this temperature. The Silver Knight manages 44C, because the fan is already on high. Neither cooler is a stellar performer at stock load, which is frankly a surprise. The 52C and 44C load temps compare to the Thermalrights at 32C and 33C, the Tuniq at 34C and the Cooler Master Hyper 6+ and Zalman 9700 at 36C. Stock load performance is below average among tested coolers.



Noise

For many enthusiasts upgrading cooling the goal is maximum stable overclock, and they will live with the inconvenience of a louder system. For other users silence is the most important factor, and these users will forgo maximum overclocking if that increases system noise levels.

There are very few power supplies that do not have a fan. While Zalman and a few others do make expensive fanless power supplies, we have not seen a fanless unit larger than 500W, or one that would be used for seriously overclocking a system. With that in mind the noise level of the system with all fans turned off except the PSU was measured. The power supply used for the cooling test bed is the OCZ PowerStream 520, which is one of the quieter high performance power supplies.

We have also measured the Corsair 620W and Mushkin 650W power supplies which are reported to be quieter than the OCZ. Both the Corsair and Mushkin are indeed quieter at idle or start up speed. However, as soon as load testing begins and the PSU fan speed kicks up the measured noise level is almost exactly the same as the OCZ PowerStream 520W.

We are currently in the process of reevaluating our cooler test bed and planning some updates. The new configuration will include a "quieter" power supply with variable speed and noise levels. We will also update to a P35 chipset motherboard with all passive cooling to the chipset. Changes to the test bed will appear as part of a future roundup with the motherboard, PSU, and CPU all upgraded to more current configurations. We are also investigating a change to a quad-core processor as a further challenge to CPU cooling.

The noise level of the power supply is 38.3 dB from 24" (61cm) and 47 dB from 6" (152mm). The measured noise level of the test room is 36.4 dB, which is a relatively quiet room with a noise floor slightly below that of the OCZ PowerStream 520 PSU.

Noise levels are measured with the test coolers with fans at both low and high speeds. Both measurements were taken at 6" and 24" above the cooling fan on an open case side. Results are then compared to the other coolers/fans tested in this category. Measured noise levels in this chart should be considered worst case. Measurements are taken with an open side of a mid tower case 6" and 24" from the HSF. Real world would be a completely closed case with a further reduction in noise. Please look for both low and high speed results in the noise graphs.

Noise Level - 6

Noise Level - 24


Water cooling enjoys a well-deserved reputation for silence. We were therefore expecting noise performance at least as good as the better air coolers. The Xigmatek AIO comes close to this performance expectation, staying near or below the system noise floor at both low and high speeds. This is particularly amazing considering the Xigmatek is based on a smaller, higher RPM 80mm fan.

The Evercool Silver Knight, however, has to be considered a disappointment in the area of noise. The Silver Knight uses a larger 92mm fan and a physically larger pump, but it's still quite a bit noisier than the Xigmatek. The measured noise levels at 6" and 24" should tell you to stay away from Silver Knight if you are looking for quiet. Both the fan and water pump are noisier than we would expect with a water system. Noise levels at the tested high fan speeds are much higher than the measured noise with the best air coolers. When turned down to low speed noise levels of the Evercool are below the noise floor, but performance drops below what is already a pretty mediocre performance curve. We expect better from a design as innovative as the Silver Knight.



Scaling of Cooling Performance

While the cooling performance of both the Xigmatek and Evercool were unspectacular at stock speeds, the performance scaling charts tell an interesting story. To be as fair as possible, given the capabilities and limitations of both coolers all cooling tests were run with the Evercool fan at the highest speed. The Xigmatek was run with fan speed on automatic to test what is happening to auto fan speeds.

Click to enlarge

At 2.93GHz the retail HSF is running at 41C, compared to 31C with the Xigmatek and 34C with Evercool. This is a delta of 10C for the AIO and 7C for the Evercool. The delta becomes greater as the overclock increases. At 3.73GHz the idle with the retail fan is 56C compared to the AIO at 42C - a delta of 14C. Similarly the Evercool delta of 7C at 2.93 increases to 13C at 3.73. Both self-contained water coolers perform better than Intel stock cooling, but neither comes close to the best air cooling results. The top Thermalright Ultra-120 eXtreme, for example, is at 33C at the same 3.73GHz. However, it is still very interesting that the Xigmatek cools better at idle at all tested speeds than the larger Evercool Silver Knight.

We also need to compare cooling efficiency of the Xigmatek AIO and Evercool Silver Knight under load conditions to the retail HSF and other recently tested CPU coolers. Load testing can be very revealing of a cooler's efficiency. A basically flat line, particularly form 3.73GHz upward, indicates the cooler is still in its best cooling range. A line that is increasing rapidly indicates a cooler nearing the end of its ability to cool efficiently. Lines which parallel the best coolers over a range of values are indicate that the coolers have similar cooling efficiency.

Click to enlarge

The Xigmatek has a very odd stress curve, which is the result of the automatic fan control by the PC. Stress temperature rises rapidly to 61C at 3.73GHz and then drops to 56C at the highest stable speed of 3.83GHz. How is this possible? It appears the fan has not kicked into highest speed at 3.73 GHz, but finally kicks into highest speed by 3.83 GHz. Fan speed change points can be adjusted in the BIOS or in software for optimum performance at the overclocked speeds that you actually run.

The Evercool fan has no auto setting, so all performance tests were run with the fan on high, as already stated. That is the reason the Evercool results under stress progress smoothly from 44 to 60 to 64C. Compared to the Xigmatek, the Evercool is clearly worse in cooling efficiency. Even though it registers 8C cooler under stress at stock speeds this is mostly the result of the Xigmatek operating its fan at lower speeds at the stock CPU setting. By the time the Xigmatek fan is on high at 3.83 GHz, the AIO cools 8C better (56C vs. 64C). This is a clear indication that the Xigmatek is a more efficient cooling solution than the Evercool with both fans at high speed. It is a bonus that the Xigmatek is also quieter at high speed.

As stated many times, the overclocking abilities of the CPU will vary at the top, depending on the CPU. This particular CPU does higher FSB speeds than any X6800 we have tested, but the 3.90GHz top speed with the Tuniq is pretty average among the X6800 processors we have tested with Tuniq cooling. A few of the other processors tested with the best air coolers reach just over 4 GHz, but the range has been 3.8 to 4.0GHz. Stock cooling generally tops out 200 to 400 MHz lower, depending on the CPU, on the processors tested in our lab.



Overclocking

As cooling solutions do a better job of keeping the CPU at a lower temperature, it is reasonable to expect the overclocking capabilities of the CPU will increase. In each test of a cooler we measure the highest stable overclock of a standard X6800 processor under the following conditions:

CPU Multiplier: 14x (Stock 11x)
CPU voltage: 1.5875V
FSB Voltage: 1.30V
Memory Voltage: 2.20V
nForce SPP Voltage: 1.35V
nForce MCP Voltage: 1.7V
HT nForce SPP <-> MCP: Auto

Memory is set to Auto timings on the 680i and memory speed is linked to the FSB for the overclocking tests. This removes memory as any kind of impediment to the maximum stable overclock. Linked settings on the 680i are a 1066FSB to a memory speed of DDR2-800. As the FSB is raised the linked memory speed increases in proportion. The same processor is used in all cooling tests to ensure comparable results.

Highest Stable Overclock (MHz)

The Xigmatek AIO reaches a stable 3.83 GHz, which is surprisingly good considering it is based on a small 80mm fan cooling 80mm radiators. The Silver Knight fared worse in overclocking, reaching just 3.81 GHz despite the larger fan, pump, and cooling fin area.

Neither of these results challenges the best air coolers with their 3.90GHz to 3.94GHz overclocks or the TEC/air hybrid Monsoon II at 3.96GHz. It certainly appears the smaller radiators and smaller physical sizes of the self-contained water coolers make it a real challenge to extract top overclocking performance from these coolers. Still, we were impressed with how well the little Xigmatek AIO performed, and we have to wonder how a similar design based on 120mm parts might perform.



Conclusion

The concept of self-contained water coolers is certainly engaging. The idea is to shrink the superior water cooling system down to heatpipe tower size. Integrate the pump, reservoir, fan, and tubing all into that heatpipe tower form factor. Package the unit completely assembled, sealed, leak-proof, and with installation at least as easy as a standard heatsink. Then sell the package at a price that is competitive with the best air cooled heatsinks.

All of this sounds like heaven to computer enthusiasts. The only missing part is whether these self-contained water cooling systems perform as well as the air coolers they compete with. Unfortunately the Evercool Silver Knight and Xigmatek AIO do not perform as well as the top air coolers. That makes them much less exciting than they might otherwise be. Neither cooler is particularly efficient at cooling at stock speeds, under idle or stress conditions. The Xigmatek overclocks the standard CPU to 3.83 GHz and no higher, while the Evercool manages an even poorer 3.81 GHz. The same CPU reaches 3.90 to 3.94 GHz on the same test bed with the best air coolers.

Water cooling is also famous for its silence, and even here these self-contained water coolers do not stand out. The small Xigmatek is mostly below our system noise floor regardless of speed and should be considered a noise success - particularly considering it is cooling 80mm radiators with a high RPM 80mm fan. The Silver Knight, on the other hand, is just too loud at the high speed needed for best cooling. Even at high speed it isn't a great cooler, and at low speed it is worse, though noise at low-speed is OK. There are still many other air coolers that best these results, however, often at lower prices.

So this great concept of self-contained water coolers falls short in the all important performance and noise areas - at least with these two coolers. We have heard rumblings of other exciting new self-contained water coolers and we are hopeful those will fare much better when they are finally introduced.

We would also be remiss if we didn't point out that despite the performance not being chart-topping, the Xigmatek should still be considered a successful design. This cooler is small, quiet, and a remarkable performer considering it is based on 80mm parts. It appears Xigmatek has a good idea in the design of this cooler, but we don't know what cooling task they had in mind when they designed it. The cooler could certainly serve as a quiet workhorse in most systems, but overclocking, at least with the capabilities of today's Core 2 Duo and Quad parts, requires a lot more muscle than the Xigmatek can deliver. Our suggestion to Xigmatek is to build future coolers around 120mm (and possibly 92mm) parts in a similar design. We suspect those coolers might finally deliver on the promise of the self-contained water cooler.

It appears that you can indeed integrate water cooling in a heatsink system about the size of a heatpipe tower. However, physics is physics, and until these designs can deliver greater water volume, larger radiator area and improved water flows they can't compete with the best air coolers. Those who want compact water cooling can select either of these designs, with the Xigmatek the more succesful design. But for high perfromance water cooling they should select a larger, more traditional water system. Those who want best performance in a heatpipe tower size cooler will find that in top air coolers like the Thermalright Ultra-120, Tuniq Tower 120, or push-pull Scythe Infinity. Perhaps that will change in the near future with newer, even more advanced all-in-one water cooling.

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