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
Comments Locked

39 Comments

View All Comments

  • dtanner - Monday, February 26, 2007 - link

    By keeping the tower short, you are keeping the mass of the tower closer to the mobo and thus reducing the stress on the push pins. As another poster has stated, with this much mass I would definitely spend the extra $10 and get the UNIVERSAL RETENTION KIT "SCURK1".
  • chienpourri - Monday, February 26, 2007 - link

    Juste a suggestion, Scyte sells a UNIVERSAL RETENTION KIT "SCURK1" that anyone can find for around 10$, it comes with a backplate and everything. As the reviewer said, I would feel very uncomfy sitting the Infinity with only brackets... However using this kit it would fix the problem. The only downside I can find is the increased cost, but 10$ for security sounds good to me!
  • orion23 - Monday, February 26, 2007 - link

    Yeah...That!
  • orion23 - Monday, February 26, 2007 - link

    Hi!

    Great test guys!

    I love how Anandtech started testing and reviewing other PC components.

    You guys are doing great so far! Keep them coming...

    And don't forget Power Supply Units!
  • Calin - Monday, February 26, 2007 - link

    I find it somewhat to be understood - as the air would flow worse inside the cooler, part of it will flow out of it using the lateral spaces - as such, contributing very little or not at all to cooling.
    I wonder how much would single fan cooling improve if the air flow would be restricted in escaping by the sides. If so, what the performance would be with a push-pull configuration and lateral restrictions on air movement (escape)?
  • Jjoshua2 - Monday, February 26, 2007 - link

    What I want to see is a more head to head test, with either the Tuniq using fans at the Infinity noise level, or the Infinity getting two higher powered fans, to see which wins.

    What I am interested in is the best performing silent/near silent fan & heatsink combo.

    But overall, I liked the article thanks!
  • Wesley Fink - Monday, February 26, 2007 - link

    We appreciate your suggestion, but we make every effort to test CPU coolers as they are packaged if at all possible. It would be a massive effort to try to go through an assortment of fans, find those singles and pairs that noise match and then replace fans supplied with the coolers with these matched singles and pairs. HSFs like Zalman have embedded fans which can't be swapped, and many top coolers use fan sizes with more limited selections than the 92mm or 120mm fan sizes.

    You have an interesting idea for an article on silent cooling, but it does go beyond the bounds of benchmarking and comparing performance of CPU coolers.
  • crimson117 - Monday, February 26, 2007 - link

    What is the ambient temperature in the room during testing?

    Does the room get hotter after a few hours of testing, perhaps skewing temperatures higher for models tested at the end of the day?
  • Wesley Fink - Monday, February 26, 2007 - link

    The ambient temperature of the room is 69F (21C) and is reasonably consistent. When running many computers in benchmarking the temperature may rise to 75F, but we check the temperature and turn off other systems during cooler testing.

Log in

Don't have an account? Sign up now