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 DDR2 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 Swiftech H2O-120 Compact and Corsair Nautilus 500 both topped out at 3870 MHz - near the top of tested air coolers but below the 3.94 GHz of the Thermalright Ultra-120 eXtreme, and the 3.90GHz of five tested air coolers. Once again test results - this time in overclocking - are near the top but do not match or exceed the best air coolers tested at AnandTech.

It was quite a surprise to find overclocks on the P35 motherboard also topped out at 3.87 GHz, particularly since we could not duplicate the 14X base multiplier on the ASUS P5K Deluxe motherboard. We achieved 3.87 GHz by choosing the 333 strap and setting a FSB of 352 with the 11X multiplier. This turned out to be the highest stable overclock on the P35 board with either water cooler - the same results found on the EVGA 680i board.

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 3.9GHz 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 4.0GHz, 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.

Scaling of Cooling Performance Final Words
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  • Gul Westfale - Monday, September 17, 2007 - link

    watercooling is still worth it ig=f you have th emoney; th etwo setups tested here are not exactly the best coolers available. also, the statement in teh article that watercoolers are quieter than aircoolers is ridiculous, after all a watercooler still has a fan thta blows air through the radiator, and that fan is jst as quiet (or noisy) as an aircooler... unless you go witth zalman's fanless reserator design.

    i'm afraid the conclusion of this article tries to tell you that all watercoolers perform like these two here, but that is simply not so. other, better systems include the aforementioned zalman reserator, the koolance exos, and several more advanced setups from swiftech. if you are interested in this, frozencpu.com is a good site to do some window sopping :0
  • Wesley Fink - Monday, September 17, 2007 - link

    We state you will likely need to spend more than $300 to possibly outperform current top air coolers. We have recently tested several systems near that price point and stand by that statement based on our tests results.

    We did not say water cooling is quieter, we just said many reviews over the years have stated water cooling to be the quieter solution. As we showed in our review that is no longer thacase unless you buy a much more expensive water system. If you read carefully you will also see we found the water pump to be the biggest noise maker and not the radiator fan.

    Finally, water cooling will have to be eons better than air if we need to spend more tha 6 times the top air cooler price just to match performance of the best air coolers. The only compelling argument in favor of water in our opinion is the ability to add video cooling blocks and possibly chipset blcos to a water system - but that cost is also high.

    You CAN buy or build a superior water system if you spend big bucks, but as one expert water cooler showed me in his tests results he had yet to find a water cooling kit that outperformed the best air coolers. His own monster water cooler was a custom built and very expensive water cooling system. If I need to go to those prices I can buy phase-change coolers that have a chance of creating sub-ambient CPU temperatures.
  • haelduksf - Monday, September 17, 2007 - link

    I'm sorry, but I don't believe you. I'm running a $200 loop, with CPU *and* GPU blocks, and getting 34 degree load temps (folding) on my q6600. Nothing special- 240mm rad, fuzion CPU block, Silverprop GPU block... frankly, you must be doing something wrong if you can't do better on water than on air.

    Plus, as others mentioned, this loop will cool any computer I own for the next 10 years, which no air cooler can claim.
  • mpc7488 - Monday, September 17, 2007 - link

    Nice article Wes, and good way to phrase it - water cooling solutions under $300 cannot outperform top air coolers.
  • Nickel020 - Monday, September 17, 2007 - link

    quote:

    Finally, water cooling will have to be eons better than air if we need to spend more tha 6 times the top air cooler price just to match performance of the best air coolers. The only compelling argument in favor of water in our opinion is the ability to add video cooling blocks and possibly chipset blcos to a water system - but that cost is also high.


    But you also need to consider that you'll use watercooling for a long time. I just recently bought my watercooling, but my 45$ waterblock was already available 3 years ago, lots of people that bought it then for a Athlon XP/754 system are still using it on a Core 2 today, and it's still very good. In the last 4 years I've had 3 different 50+$ air coolers in my main rig, that kind of adds up as well.
    Watercooling is a big initial investment, but pump and radiators will last you 5+ years and waterblocks last several years as well. If you're a guy that buys one 50+$ heatsink a year, then watercooling is only marginally more expensive (if at all) then air.
  • strikeback03 - Wednesday, September 19, 2007 - link

    The only reasons to upgrade to a newer cooler (air or water) is if either the performance is significantly better, or the cooler does not support whatever socket you move to in the future. These factors are the same for air or water, so in theory both should have a similar lifespan. If water cooling sees improvements in the next few years the way air has in the past few years, you would probably upgrade your water setup sooner than you think as well.
  • KeypoX - Tuesday, September 18, 2007 - link

    that is not true i bought the koolance case/water cooler years ago and it was no match for my current air cooler. On top of that the water block i had bought the 200 koolance was dropped and no longer supported for newer chip sets.

    I had a athlon 2600xp OC with the water cooler but it wasnt as good as air. And it had to much upkeep and a TON of noise.

  • RamIt - Monday, September 17, 2007 - link

    What happened to paet two of the micro atx motherboard roundup?

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