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: 1.5V
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 Scythe Infinity overclocking was just average in the stock single fan configuration - reaching 3.83GHz with complete stability. However the second fan in a push-pull configuration allowed the Infinity to match the highest overclock on air we have seen with this CPU. At 3.9GHz the Tuniq Tower 120 was still cooler, but the Infinity still managed to hold 3.90GHz with stability during our load testing.


These overclocking results were particularly interesting since we have seen some forum comments that the second cooling fan made little difference on the Infinity. Our results indicate the second cooling fan can make a very significant difference in both cooling and overclocking the Infinity.

The smaller differences others have reported may have been the result of a less demanding test configuration or perhaps it was a result of a better single cooling fan on the tested Infinity. To test this second possibility, a higher RPM and CFM Silverstone fan was mounted on the Infinity as a single fan and the highest overclock was tested. The Infinity with the beefed up fan reached 3.85Ghz - a little higher than the 3.83GHz with the stock fan - with temps about 1C lower than the "silent" fan shipped with the Infinity. Clearly a fan pushing more air improves performance by a small amount, but it still does not match the performance of two "silent" fans in a push-pull arrangement.

Scaling of Cooling Performance Noise
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  • SmokeRngs - Wednesday, February 28, 2007 - link

    quote:

    Sure it makes for interesting reading, so I guess I can't blame you too much, and the audience at Anandtech surely eats it up. I would just tell you I'd rather not have reviews cluttered up with this rather petty data.


    The information you wanted is there. Why are you complaining? There are plenty of people that don't care about the information you want but do want the information you deride. Both are there in a clear and concise manner for those that want to see one or both.
  • shabby - Monday, February 26, 2007 - link

    People who buy $50 heatsinks dont buy them because they're quiet, they buy them so they can overclock their cpu's. Plus they probably stick higher cfm fans, so they're not quiet anymore.
  • Zambien - Monday, February 26, 2007 - link

    I disagree. When I bought my Zalman 7700cu for my current PC, the main reason was that it would provide similar cooling to my current HSF, with less noise. I didn't like the fact that my computer sounded like a jet engnine. I'm sure some people fall into the category, but others do not.
  • cujo - Monday, February 26, 2007 - link

    why wouldn't you test with overclocks?
  • arswihart - Monday, February 26, 2007 - link

    Not to mention they are talking about 50Mhz differences in OC to separate better and lesser performing heatsinks. Come on, that isn't even a significant difference. Did they repeat the result on multiple systems, or just the one. Does it matter? Of course not.
  • arswihart - Monday, February 26, 2007 - link

    A heatsink doesn't do anything magic to give you higher OC's, it gives you lower temps, which will then let you OC higher.

    Measuring a CPU's OC is looking at data that is a step removed from what you should be looking at, which is simply the temperature. I could care less what they get to OC to, it will be almost certainly different for anyone who buys the heatsink.

    The only thing that I think is worth taking away from any heatsink review is: installation caveats, temps, and noise.
  • shabby - Monday, February 26, 2007 - link

    I find it funny that the infinity cant beat the tt120, does it have thicker heatpipes or what. What part of the tt120's construction make it better then other beefier/bigger coolers?
  • Superdoopercooper - Monday, February 26, 2007 - link

    The first rule in A-B testing is to hold EVERYTHING constant except for the items being examined/tested.

    Therefore, in ALL of your heatsink reviews, the system down to the THERMAL COMPOUND should remain fixed, even if the heatsink ships with some "higher end" stuff.

    I think it would be wise to pick ONE thermal compound and use it on EVERY heatsink test. Then you are testing the performance of the heatsink (i.e. Heatsink #1 is better than Heatsink #2, with no exceptions), and not the thermal grease + heatsink.

    I would hate to think that heatsink #1 was the best, but only because it shipped with better compound than another. I think many people ponying up for these higher-$$ heatsinks will pony up $6 for some good thermal grease.

    Then, if you want to do an additional test that comments on the performance of the included thermal grease, that would/could be helpful to potential buyers.
  • Wesley Fink - Monday, February 26, 2007 - link

    I can easily link you to a review from a respected source that proves toothpaste and Kraft Vegemite are superior in cooling to Arctic Silver 5 :-) I have tested many thermal compounds and found little differnece among the quality products. That conclusion was a rude awakening for me. I have found much more variation in perfromance in how the thermal grease was applied than I have ever found in the thermal compounds themselves.

    Thus far, all of the tests have used our standard silver-colored (but no real silver content) tube thermal compound except the Thermalright MST 6775 and the Zalman pair. These came with top thermal grease, and yet none of the three beat our Tuniq or this Infinity. If the cooler company cares enought to supply a premium thermal compound we test with that compound.
  • Superdoopercooper - Monday, February 26, 2007 - link

    If it is true that all thermal compounds are nearly equal, then I guess that's fine. I would like to see the link, actually.

    That still doesn't change the fact that the best A-B testing holds EVERYTHING constant except the single item being tested.

    Since AT is the site I hold in the highest regard in terms of info on computer components, I thought I'd just throw up my $0.02 on ways to maybe make these tests "better" and/or more scientific.

    Could just be my test engineering background talking. :-P

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