The Grid in My Basement, part 3: That Sinking Feeling

Size matters. At least when you are building rackmount machines. Of course were I not suffering from sleep deprivation when I made my hardware purchasing decisions I would have realized that you can't put a MASSIVE heat sink into a tiny space, but such is life.

Anyway, the very spiffy Blue Orb II CPU cooler is never ever gonna fit in the 2U case I bought. That was evident by inspection before I even unpacked the coolers. Had I done my homework on the motherboard and case dimensions I would have realized that a package with a combined fan + heatsink height of 90.3mm would never fit. Not only that, but the heatsink has length and width dimensions of 140x140 which means it might not fit the motherboard at all. There's a huge row of capacitors next to the retention module base, and the DIMM sockets are proximate on the other side. This is all badness from the perspective of installing a massive heatsink.

So with a heavy sigh I file for my first RMA from Newegg and package the Orbs for shipment back. Bummer drag, they looked so cool too. So I start looking for an appropriate K8 heatsink for my new nodes, and the fun really begins.

First, you may be wondering why I didn't use the cooler that came with the CPU when I bought it. Well, in order to save money I bought the OEM version of everthing I could. That eliminates a lot of unnecssary packaging, instruction manuals, and in some cases features - like the CPU cooler on my AMD X2s. So I need to buy a cooler on the aftermarket.

The assumption that manufacturers make is that you WILL overclock if you are buying an aftermarket cooler. Therefore, the heatsinks reflect this assumption and most are massive. Looking at heatsinks in close up is sorta like looking at big scary machinery. Pipes and tubes run in all directions, massive banks of fins jut out at weird angles and rise up toward to sky towering over the motherboard. None of these devices are particularly well suited for the tight space of a 2U (or heaven help you a 1U) case.

I start shopping around for low-profile CPU coolers for 2U cases and run into several problems. First, there aren't too many cooler vendors out there that make this stuff. Second, the ones that do aren't terribly interested in Socket 939 applications. Third, the low-profile stuff tends to be crazy expensive - $95 for a low-profile heat sink and fan? No thanks...

So I pick up a ruler, open up the case, and start measuring. And measuring. After a good deal of plotting, I calculate that my heat sink can be no more than 70 x 70 x 65mm. And then I start shopping. And shopping.

Finally, after literally 2 evenings wasted googling around, I hit on a cooler/heatsink sold by ASUS - the same manufacturer that makes the motherboard I am using. I look at the height dimension and am psyched - the combined total of both devices is only 55mm tall! The bad news is that the heatsink runs 77 x 68 x 40mm - meaning that it's too big potentially. I look on the ASUS website (sidebar your honor: remind me to rant and rant later about web sites that provide everything BUT the information you need) and find nothing helpful regarding compatibility with their own motherboards.

So I reason as follows: The height dimension will fit just fine; the heatsink will probably fit an ASUS motherboard since ASUS makes both; the absence of a compatibility list means it's compatible with all their offerings or somebody is just lazy. So I bite the bullet and order up the ASUS Crux K8 MH7S 70mm Hydraulic CPU Cooling Fan with Heatsink and hope for the best.

2 days later I get the parts, and a couple days after that I open up the build-in-progress machine and install the heatsink. Have I mentioned how stressful putting a heatsink in can be? I mean there you are with all this expensive hardware that looks pretty darn fragile, and you are pushing down on it with no small amount of force trying to more-or-less permanently mate the CPU to the heatsink. Every time I do this I expect the motherboard to crack or something equally as awful.

Good news! The new cooler fits perfectly. It clears the lid of the case beautifully, and the dimensions of both heatsink and cooler are within the perimter of the retention module.