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: 1.90V
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 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 OCZ Vindicator with the stock fan could only reach 3.80GHz overclock with stability. This result is average to below average among the tested heatpipe towers. However a change to the 72 CFM 14 dB-A SilenX IXTREMA 120 allowed us to push the overclock to 3.90GHz with complete stability. This matches the top tier of overclocks achieved by the Tuniq Tower 120, Thermalright Ultra 120/Scythe SFLEX, Cooler Master Hyper 6+, and Scythe Infinity with dual push-pull fans.

The only air cooler that has reached higher than 3.90GHz is the Thermalright Ultra 120 Extreme, which was featured at CeBIT. We managed 3.94GHz with that top air cooler. The hybrid TEC/air Monsoon II Lite reached 3.96GHz in benchmarking, but that cooler combines active TEC cooling with passive air cooling and would be expected to reach higher overclocks than an air-only solution

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.

We measured noise levels with the OCZ Vindicator with both stock and SilenX IXTREMA fans under both load and idle conditions. As might be expected with fans with noise ratings of 18.5 dB-A and 14 dB-A, the measured noise was below our system noise floor at both 6" and 24" positions above the open side of our system case.

There are virtually no power supplies that do not have a fan. While Zalman and a few others do make an expensive fanless power supply, 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 power supply was measured. The power supply used for the cooling test bed was the OCZ PowerStream 520, which is one of the quieter of the high performance power supplies.

We have also measured the Corsair 620 watt and Mushkin 650 watt 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 and the measured noise level is almost exactly the same as the OCZ PowerStream 520 watt power supply. In keeping with our "real world" philosophy of noise, we consider the PSU load noise to be the more realistic noise level of power supplies. We do plan to evaluate additional power supplies and configurations in our upcoming 120mm fan roundup, but we will tilt to real world rather than procedures that test fans on foam blocks or hard drive noise with their "noisy" side pointed toward a foam block.

The noise level of the power supply was 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 would be considered a relatively quiet room with a noise floor slightly below the OCZ PowerStream 520 PSU.

Noise Level - 6

Noise Level - 24

Measured noise levels in this chart should be considered worst case. Measurements were taken with an open side of a mid tower case 6" and 24" from the HSF. Real world would be a completely closed case resulting in a further reduction in noise.

Any 120mm fan should be mountable on the OCZ Vindicator. The fan clips connect to the outside mount hole, which means both open post and the more common closed post fans will work properly. The stock OCZ fan is closed post and the SilenX is open post. This means the SilenX will work on any cooler we have reviewed thus far - including the Thermalright Ultra 120 and Ultra 120 Extreme.

Scaling of Cooling Performance Final Words
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  • Chunga29 - Thursday, April 5, 2007 - link

    I have to wonder if part of the issue might be your sound meter. Some meters are only good to measure levels down to ~35 dB. I've played with a sound meter at work (the HR department had to conduct "ergonomics testing" [rolls eyes], and as the IT guy I had to make sure the PCs weren't "too loud". Not sure what we were supposed to do if the Dell systems made too much noise for comfort, though....) Our offices were at a pretty consistent 45-50 dB during the day. Even a normal conversation would jack that level up to 55-65 dB (depending on the speaker(s).

    At night with all the computers shut down, however, the noise level dropped below 30 dB and our meter was no longer useful as far as I could tell. Of coruse, at that point even moderate breathing in the vicinity of the meter would increase the detected noise level, as would walking. In my experience, then, 30 dB is basically extremely quiet (even "silent"), and anything lower than that is not likely to be meaningful unless you are testing in some soundproof location.

    I would think in a standard house with all of the noise generating equipment (fans, refrigerators, heat/AC, TV, etc.) shut down that reaching 25 dB should not present a problem. Whether your equipment can reliably measure noise levels at that point is the real question.
  • Wesley Fink - Thursday, April 5, 2007 - link

    CORRECTED - Editors would also like to be able to edit their comments :)

    It seems that every cooler or hard drive review that we have recently posted is met with rocks from SilentPC "readers". This is really puzzling, since we have stated many times that we admire the good SPC has done in making manufacturers pay much more attention to the noise their components generate. There are many more choices of low-noise components because enthusiasts and sites like SPC have pointed out the noise offenders, and buyers have bought the quieter version instead.

    Testing component noise in isolation provides useful information, but AnandTech has a long tradition of "Real World" testing. Overclocking also has very different demands than building the quietest PC to run at stock speeds. The noise floor for any working system will be the power supply generally, and possibly the video card or ambient room noise. It doesn't matter in our approach how quiet a fan is if the power supply is 20db louder. This is pretty obvious but it is rarely mentioned when people are screaming about a fan at 14dbA versus a fan at 18dbA or hard drives that are 2db apart at 26db. Does it really matter if the power supply in the system is at 36dbA?

    We do plan to move to a quieter power supply in our test bed as soon as we can find one that meets our needs. We have looked at several of the power supplies proclaimed in comments in past reviews as "MUCH quieter than the OCZ PowerStream 520W". They were quieter at idle, but at load those power supplies were virtually the same noise level as the OCZ. Idle noise might matter if you sleep in the same room with your computer, but you can't do anything with an idling computer except look at it. We believe the normal operating noise measurements are the noise levels that matter most.

    If readers prefer the review approach of another site that is their right, but we do hope they will stop investing so much emotion in their comments. We think there is room for both the component isolation approach and the AnandTech "real world" approach. We also don't think there is any "right" or universal truth to be gleaned here - they are just different approaches.

    We chose the SilenX fan because it specified higher output than the SFlex at noise levels that were far below our system noise floor. We could just as easily have used the SFlex with a specified 63.7cfm instead of the 72cfm of the SilenX. However, since we have not yet done our fan review we didn't want to tilt sentiment too strongly to one brand name so we chose another quality product to put another deserving brand in the spotlight.

    Our plan going forward is to complete a few more waiting cooler reviews, and then select the top air cooler from our reviews. This will be followed by a fan roundup testing fans on our top performing HSF. New reviews will then be tested with stock components PLUS the top fan from our roundup. This should provide some consistent answers to some valid real-world questions.
  • Wesley Fink - Thursday, April 5, 2007 - link

    Yes, it appears SPCR had the SilenX wars recently, but the fan in this review is NOT the same one tested at SPCR. Someone needs to back away and also point out that while the SilenX fan did not match it's noise specs in the SPCR review it DID test at less than 18db, which is still exceptionally quiet. In addition a recent SPCR review of the 14DBa SilenX power supply concluded "The SilenX 14 dBA advances the state of quiet fan-cooled power supplies by another few decibels."

    The SilenX DID improve the cooling ability and the overclocking ability of the OCZ Vindicator compared to the stock fan, and it did so at measured noise levels below the noise floor of our system. These things we did confirm in our review. We did not test the claimed specifications since our concern was cooler performance, overclocking, and noise lower than our system noise floor.
  • ATWindsor - Thursday, April 5, 2007 - link

    Less than 18 dba at 10 cfm that is, at full speed it is noticably more noisy. (the SPCR-test puts it at 33 dba), I have myself measured fans, and the specs are more or less hit and miss, my conclusion was that the very best indicator of noise is the rpm of the fan. 14 dba isn't even close to realistic at stock speed. Hower also SPCRs reults are not entirely reliable at levels below 20 dba, that is very quiet for a room not specifically designed for it, and most sound-level-meters (even good ones), have a noise floor on the 15 dba-range.

    The problem is that nobody knows how these numbers are measured, 14 dba at what range? 20 meters? It like saying "this heater will give you a room-temperature of a 100 degrees F. Its more or less meaningless when you now nothing about the room, as a heater, sound should be stated as sound-power. Then you can easily calculate sound pressure level in a given room at a given distance.
  • coldpower27 - Thursday, April 5, 2007 - link

    Are you going to be doing some comparisons to the value coolers?
    Sunbeam Silent Whisper Socket 775
    Arctic Cooling Freezer 7 Pro
  • Wesley Fink - Thursday, April 5, 2007 - link

    A value cooler roundup is planned for the future.
  • Bumtrinket - Thursday, April 5, 2007 - link

    I think what's got up SPCR readers' collective noses is the way you allowed SilenX's claim to pass without challenge, and presented it as established fact: "Replace the stock fan with the quiet (14 dB-A) and powerful (72 CFM) SilenX IXTREMA 120 and the Vindicator can overclock with the best." Unless there's some way SilenX have found to defy the laws of physics, there's no way a fan capable of shifting that much air could be that quiet.

    I'm not sure if you're aware of SilenX's history of deceit as regards SPCR, but that was like a red rag to a bull.

    Incidentally, you state that the Scythe Ninja needs a mounting bracket for use with Socket 775 mobo's - that's not true, as it's used the standard Intel pushpin method since revision B was launched several months ago. I'm a bit surprised you consider this would be "good news," especially in a heatsink of this size and weight.
  • Wesley Fink - Thursday, April 5, 2007 - link

    Easy mounting is always good news, but there are valid concerns about the huge weight being supported by something as flimsy as pins. That concern is also stated in the review.

    I have the Ninja Plus Rev. B in for review and the bracket and instructions for the AMD AM2/754/939/940 is NOT a push pin install. For AMD the bracket attaches and clips onto the center pin of the AMD mounting cage - which is supported by screws and a back plate. You still do not need to remove the board or the "cage" to install the Nija Plus Rev. B on an AMD board. THe bracket for Intel 775 IS push pin, but it is the only push pin solution.
  • Bumtrinket - Thursday, April 5, 2007 - link

    ermm... OK, but I was referring specifically to socket 775, not AMD. It's hardly worth arguing about, but you might want to correct what you actually said: "The good news is the OCZ Vindicator comes preconfigured for Intel Socket T, where the Scythe requires installation of a bracket before it can be used on that socket. Mounting socket plates on both coolers is basically the same."

    I was rather hoping there would be a bolt-thru plus backplate solution for socket 775, which would have avoided the main gripe with the Ninja, but it seems it's not to be.
  • Wesley Fink - Thursday, April 5, 2007 - link

    It seems that every cooler or hard drive review that we have recently posted is met with rocks from SilentPC "readers". This is really puzzling, since we have stated many times that we admire the good SPC has done in making manufacturers pay much more attention to the noise their components generate. There are many more choises of low-noise components because sites enthusiasts and sites like SPC have pointed out the noise offenders, and buyers have bought the quieter version instead.

    Testing component noise in isolation provides useful information, but AnandTech has a long tradition of "Real World" testing. Overclocking also has very different demands than building the quietest PC to run at stock speeds. The noise floor for any working system will be the power supply generally, and possibly the video card or ambient room noise. It doesn't matter in our approach how quiet a fan is if the power supply is 20db louder. This is pretty obvious but it is rarely mentioned when people are screaming about a fan at 14dbA versus a fan at 18dbA or power supplies that are 2db apart at 26db. Does it really matter if the power supply in the system is at 36dbA?

    We do plan to move to a quieter power supply in our test bed as soon as we can find one that meets our needs. We have looked at several of the power supplies proclaimed in comments in past reviews as "MUCH quieter than the OCZ PowerStream 520W". They were quieter at idle, but at load those power supplies were virtually the same noise level as the OCZ. Idle noise might matter if you sleep in the same room with your computer, but you can't do anything with an idling computer except look at it. We believe the normal operating noise measurements are the noise levels that matter most.

    If readers prefer the review approach of another site that is their right, but we do hope they will stop investing so much emotion in thier comments. We think there is room for both the component isolation approach and the AnandTech "real world" approach. We also don't think there is any "right" or universal truth to be gleaned here - they are just different approaches.

    We chose the SilenX fan because it specified higher output than the SFlex at noise levels that were far below our system noise floor. We could just as easily have used the SFlex with a specified 63.7cfm instead of the 72cfm of the SilenX. However, since we have not yet done our fan review we didn't want to tilt sentiment too strongly to one brand name so we chose another quality product to put another deserving brand in the spotlight.

    Our plan going forward is to complete a few more waiting cooler reviews, and then select the top air cooler from our reviews. This will be followed by a fan roundup testing fans on our top performing HSF. New reviews will then be tested with stock components PLUS the top fan from our roundup. This should provide some consistent answers to some valid real-world questions.

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