Re:The fanless spinning heatsink: more efficient, and immune...
by sbierwagen on Tuesday July 12, 2011 @04:03PM
(#2756283)
I would hesitate twice and then hesitate one more time before placing any confidence at all in a manufacturer supplied number for a statistic like C/W, which can be so easily fudged, as we have seen.
But yeah, I've been out of the overclocking scene for a couple years, now. I have no idea how well heatpipe heatsinks perform, other than "better".
As for the danger of a large piece of metal spinning at kRPM, I agree. This is bad enough that there probably would have to be an safety interlock on computer case access panels that reverses the impeller to a halt when the enclosure is opened.
Re:The fanless spinning heatsink: more efficient, and immune...
by jarek on Tuesday July 12, 2011 @06:25PM
(#2756899)
SPCR is a review site pretty serious about their methology; their newest heatsink reviews don't have °C/W figures due to difficulty measuring the power output of socket 1366 CPUs, but here's a mid-2009 review of a huge heatpipe/tower heatsink: http://www.silentpcreview.com/scythe-mugen2
Page 6 states °C/W values of 0.29 down to 0.14 depending on the amount of air pushed with the fans. SPCR's test fans are pretty low-flow to begin with (47 CFM/1080 RPM at 12 V), so you could probably go slightly lower by using real screamers.
These days you can find huge coolers with (or at least claimed[1]) less than 0.2°C/W. Most of the lower power CPUs (40-50W) can run fanless at decent temperatures with half a kilo of metal fins + some heatpipes, and you can mount that kind of heat spreader easily with bolt-through screws.
Also, that metal fan is dangerous! If you ever touched even a slow-spinning plastic fan's blades, you know how painful (or bloody) it can be. And that was only a very light plastic blade, probably less than 30 grams. Now think about the momentum of a 200 gram metal thingie spinning with more than 1000rpm (as I understand, they tested it to 7-8000 rpm). You really want to be sure you will not touch it while spinning. But if you enclose it, even in a wire cage, the performance will decrease.
1: http://www.scythe-usa.com/support/cpu/006/scmn1000_scnj1000p...