Saturday, October 13, 2007

CPU Cooling

The Intel Core 2 Duo 6750 processor comes in a retail box from NewEgg and others, complete with a processor cooling solution consisting of a small fan and cooling fins. Concerned about noise, I searched for a passive design, without a fan, to replace the Intel cooler, and came across the web site, where CPU heatsinks of many types are compared. One of the evaluated heatsinks is the "stock" fan/fin cooler provided by Intel with the boxed processor.

Intel stock cooler According to FrostyTech, the Intel cooler is very quiet, one of the quietest coolers evaluated. The article includes a large table of coolers, with the stock Intel 35 db quieter than the noisiest cooler and about 20 db quieter than the median. The description was also very favorable, it "operates very quietly at its default speed."

However the fan was not tested in the mode in which it will actually be used. FrostyTech used a 3-pin connector, which causes the fan to adjust its speed according to ambient air temperature. In the Intel boxed solution a 4-pin connector is used, permitting the fan speed to be programmed according to the actual CPU temperature, in which case it might run faster and make more noise. Nevertheless, it's my guess that the Intel fan will be quiet enough, probably much quieter than the two mirrored 320 Gb disk drives that will be running in the same cabinet, and probably also quieter than the cabinet fan.
Intel stock cooler
FrostyTech also evaluated the cooler's actual cooling ability, applying an 85-watt heat load, which is slightly higher than the 65 watts dissipated by the E6750 at maximum current. Here the Intel cooler did not fare as well, ending up near the top of the list with the highest CPU temperature (least cooling), some 20 degrees C higher than the best cooler. Again, though, the fan was not operated in the mode in which it will be used in my computer. I suspect that Intel knows what it is doing, and the cooling will be adequate for my relatively tame application.

Intel stock cooler I did find two heatsinks by Spire, both of which include a noisy fan, but which (according to Spire) can be used without the fan if the heat load is not excessive. One of these was also evaluated by FrostyTech, who downrated it for its bulkiness and thought it was difficult to install and remove. They did not test it without the fan, but considering the tests they did perform I doubt that it would perform very well without the fan unless there was a gale wind flowing through the cabinet. In my modest search I did not find any other passive CPU heatsinks. These are available on some graphic accelerator cards (which are CPUs in their own right) but apparently not for CPUs. If you know different, please let me know.

Bottom line: I'm going with the stock Intel cooler unless the noise is a big surprise. If so, then I'll look at other coolers.

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