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Roundup of Eight Horizontal CPU Coolers
ThinSkin writes "ExtremeTech has done a roundup of eight sideways-gusting CPU coolers under fifty bucks to see if they can keep an overclocked Athlon FX-60 from welding itself to the motherboard. In addition to temperature testing, much emphasis was placed on noise reduction, which with some coolers can be improved by adjusting fan speed or even removing the fan from the cooler."
For example I noticed they didn't like the Arctic Cooling Freezer 64 Pro. That supprised me, since I have the Pentium D version of the same thing and I think it's great. Why didn't they like it? Well it didn't cool as well as others... Right, see it's designed to be silent, but cool well enough. On my board, the BIOS decided that 50 degrees is the temperature at which the processor ought to operate (can alter that but I haven't). If the processor gets hotter than that, it speeds up the fan, if it drops much below that, it slows it down.
Well the net effect is I can't hear my CPU fan. When my cores are mostly idle like web surfing, it runs at like 800RPM and is totally inaudible over other noise. During intense work it spins up to like 1500RPM and you can hear it, but just barely. When told to run to maximum (something like 300RPM, don't remember) it gets to be moderatly noisy, though not annoying.
The point is that no, it doens't keep my processor ultra cool, but I've seen no reason as to why I should care. CPUs can run quite hot with no problems. What it does do is maintian my processor at a safe temperature with a minimum amount of noise. To me, that is golden.
Also something to note is that often the biggest, baddest heatsinks aren't safe. They are too heavy and can crack the motherboard. Won't happen right away, but there's maximum stresses you are supposed to put on them. It's like 500g in Intel's case. So if you buy some massive copper job that weighs a kilogram, don't be supprised if your board cracks a few months down the road.
Interesting that you tested a cooler without a fan. I often wonder how much real-world benefit a fan gives. Particularly if you consider the build up of dust that can accumulate over a relatively short period (6 months). I have a Zalman CNPS7000Cu (the fan/flower one) on my Athlon64 3500. I have removed it and cleaned it twice already (in 12 months), and each time it was caked with dust. And no, the case isn't parked on a carpeted floor.
If you didn't pull so much air past the fins, I'd say that the dust wouldn't accumulate so quickly. The accumulated dust would provide a significant thermal impedance to the system, probably negating all the benefits of forced convection.
The other thing I ponder is the thermal benefits of the outer ends of the fins. I believe the thermal path to the extreme edges of the 'flower' is so long that, if you plotted temperature vs thermal path, the extreme ends would have a curve almost horizontal. So I wonder how much smaller could you make the diameter of the heat sink without signficant impact on performance.
Is there an ideal (rule-of-thumb) aspect ratio for heat sink fins?