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: 2.00V
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 Thermalright Ultima-90 reaches a stable 3.90 GHz, matching the top performers we have tested like the Tuniq 120, Thermalright Ultra-120, Scythe Infinity with push-pull fans, and the Scythe Ninja Plus B/OCZ Vindicator running a high output SilenX IXTREME fan. The only air cooler that outperforms the Ultima-90 in overclocking is its big brother - the Ulltra-120 eXtreme.

These results are with a high output 120mm fan. Results with a 92mm fan are slightly lower, with a top overclock of 3.87GHz. As seen in the scaling charts the 120mm and 92mm fan results are almost the same to the top of the speed charts. Cooling performance is also about the same with either a 120mm or 92mm driving. However, the 120mm fan allows a slightly higher overclock.

If wattage is considered, a stock X6800 consumes about 75 watts, where the 3.83GHz OC pulls about 150 watts - double the amount required at stock speed. At the voltage required for stability at 3.90 GHz with a 120mm fan, the CPU wattage is around 161W. The highest air result ever with this CPU at 3.94GHz translates into about 165W, where the 92mm top of 3.87GHz translates into around 158W. Considering the smaller size and reduced weight of the Ultima-90, this performance can only be considered outstanding.

Note that a C2D pushed to the incredible overclocks they can reach draws a lot of power, and our cooling test is designed to find where the top coolers fail. Keep this in mind when looking at our cooling results. Many of the middle coolers in our roundup have done very well when tested with AMD processors or with less demanding cooling test procedures.

Scaling of Cooling Performance Conclusion
Comments Locked

38 Comments

View All Comments

  • Wesley Fink - Monday, August 20, 2007 - link

    The performance of the stock Intel Retail cooler also needs to be put in perspective. In our testing the Intel Retail HSF is stable to 3.73GHz at 1.50V. That translates into about 137W with an X6800 CPU.

    While early Intel Retail 775 coolers were very noisy, stock coolers since late Presller and through Core2 have been very quiet, as you can see in our noise measurements in reviews.

    With a stock cooler performing this well, we think a cooler HAS to provide performance better than Intel Stock to persuade you to buy it. We could argue using your logic that the difference between the Intel stock of 3.73GHz and the top 3.94GHz is only 200 megahertz and so it is minor. The wattage difference, however, is between 137W and 166W, which is a significant difference in the ability of coolers to dssipate heat.
  • ssiu - Monday, August 20, 2007 - link

    I have a serious question regarding this. 3.73Ghz is perfectly fine with me and I don't care for another 200Mhz. The louder noise of stock cooler is also okay with me. So that leaves the temperature difference of 71C for stock cooler versus (43C for Ultra-120 eXtreme, 47C for Ultima-90, 59C for NinjaB, 62C for Infinity, etc.) Does the stock cooler's higher temperature make the CPU die prematurely? Or is it a case of "the CPU is designed to withstand 71C; at 3.73Ghz, 71C may make it last 5 years instead of 10 years at 43C, but even at 71C it will become obsolete (too slow) before it will die"?
  • Wesley Fink - Monday, August 20, 2007 - link

    Intel shows a maximum recommended temp of 60.4C at 75W (stock) for the X6800 in their thermal design document at ftp://download.intel.com/design/processor/datashts...">ftp://download.intel.com/design/processor/datashts... However, 3.83 Ghz is about 137W and we really don't know the recommendations at these higher frequencies since they represent overclocks.

    It would seem reasonable to aim for lower than the max recommended temperature at stock speed if you are aiming for longevity of the CPU. That cahart can be found on p.85 of the Intel PDF linked above.
  • Wesley Fink - Monday, August 20, 2007 - link

    Correction - 3.73GHz at 1.5V is about 135W - which is the max stable speed with the Intel stock HSF. Sorry for the typo.
  • Jedi2155 - Monday, August 20, 2007 - link

    To Coolerman:

    I had the Tuniq 120 for about 6 months on my E6600 setup, and although it was a great cooler and signifcantly cheaper than the Ultra 120 Extreme, it just isn't as good when all things are considered (size, noise levels, fan options) and the Ultra 120 extreme is worth the price difference IMO. The size made installation ever so much easier than the Tuniq and improvement in cooling (even with a cheap $7 thermaltake fan) was significant (went from 80 C Intel TAT to around 70 C).

    I definitely think that you should recategorize the coolers, but instead of temperature, how about price range or probably best category SIZE.

    I've had a number of issues during builds for friends, where the a certain cooler wouldn't fit (like a Tuniq 120 or the Ultra 120 Extreme) fit inside a case without significant modification (with a pair of pliers and remove a good section of the case).

    That should help us decide better than just pure temperatures and overclock speed.
  • CZroe - Monday, August 20, 2007 - link

    I think that sorting by value/prices is a bad idea. Have you looked for the actual prices? Anandtech's reported suggested prices and "actual" market prices have been FAR lower than I've been able to find in each cooler that interested me. I eventually just settled on the Ultra-120 Extreme and the same fan from Newegg and paid FAR too much.

    Perhaps the observed difference is because they keep getting price results for similar models (which complicated my own searching) or the only places that still carry some of these still have them because they always overcharged.
  • tom0099 - Friday, August 6, 2021 - link

    http://google.com">google
  • tom0099 - Friday, August 6, 2021 - link

    <a href="https://google.com">google</a>

Log in

Don't have an account? Sign up now