Slow Servers' Gemlog: Custom Heatsink
Posted: 2026-03-03
My preferred hardware configuration has some tricky elements, as far as sourcing goes.
One of them is a C32 (AMD) heatsink. Specifically, 1U.
It appears that there is one such heatsink available, and it's only available brand new. I can find it from Dynatron on Ebay for $39.99, plus $22.04 shipping.
I feel like this is a little outrageous. It's better if I buy more than one at a time, but potentially over $60 just for a heatsink, on my old hardware!
Alternatives...
Though I don't mind a brand new heatsink because it's basically all copper and completely recyclable, I would still prefer a used one. So I looked into ones that might happen to fit, or could be retrofitted.
The first alternative was a "SuperMicro SNK-P0042P." It's a 1U heatsink for G34. I thought I read on a forum somewhere that G34 heatsinks worked on C32. And maybe that's true some of the time. Unfortunately, the screws were too far apart, so it was a non-starter. If you can use it, live in the US and pay to cover the cost of shipping, I'll send it to you! (Sorry, international shipping is a bit pain these days.)
The second alternative was a "HP 453434-B21." Also has BL495C as another part number. Says F1207 socket, just like Dynatron's heatsink (well, it says F1207 and C32.)
The HP heatsink's screws lined up. So far, so good!
Photo Journey
Heatsink resting on CPU.
Seems to line up well at first glance.
Heatsink resting on CPU, side view.
Not quite right, it's too wide! Sitting on a capacitor.
Heatsink in bench vice.
There's a wide side and a narrow side (screws are offset). I picked the wider side to trim so I wouldn't have to trim both sides. I think this technically means it goes on backwards. There's a angle to the center fins, so it probably matters slightly. Someone more particular might trim both ends, so it could fit without. I just thought it looked too close to the memory with the wide side towards the memory. The narrow side still hung up on that same capacitor, so both ends really would have to be trimmed for me to be comfortable.
I bent the fins over marking the path I wanted to cut with the angle grinder.
Trimmed heatsink in bench vice.
A quick trim later.
Two trimmed heatsinks on top of the bench vice.
I had two heatsinks, so went ahead and did both of them.
Dab of Arctic Silver 5 on a 4256EE Opteron.
Time to install! I tried to follow Arctic Silver's instructions, minus the thorough cleaning steps.
Trimmed heatsink installed, side view.
So far so good.
Trimmed heatsink installed, other side view.
Ample memory clearance. Excellent!
Trimmed heatsink installed, 90 degree view.
Maybe not quite right. It's too tall! If it weren't going into a 1U chassis, it'd be fine. But as you can see, it sits proud of the case. Not good.
I'm not going to say this was the wisest response, but with the heatsink already installed with thermal compound, I decided to improvise in place...
Trimmed and shortened heatsink.
I bent fins over and removed some, selectively. I tried to maximize fin area while making it clear the 1U chassis.
I first used my knife to separate the fins. They were sort of locked, at three points, with tabs. I removed fins by pulling them out with pliers. I bent them over mostly by hand.
Trimmed and shortened heatsink, close up.
Here it is, up close. Enterprise ready! (This is a joke.)
Conclusion
There was a lot that went wrong here. The heatsink weren't quite tall enough to make me think that they might be too tall. Not normal 2U heatsinks, for sure, so I assumed they must definitely fit 1U.
Pricing wise, these heatsinks are cheaper and pretty available.
However, the trimming alone makes for a lot of copper shards. It makes me nervous about the right one falling on the right pair of pins and shorting something out. I did blow out both of the heatsinks with my air compressor, but I don't think it was perfect by any means.
I could have shortened the heatsink vertically with the angle grinder as well. I might be open to trying that, but the fins are so thin that they get quite sharp and they're not the nicest to cut. It would also make way more shards than even the width trimming did.
Now obviously, the heatsink has had a great reduction in surface area, thus capability to manage heat. The reason I considered such is because my 4256EE Opterons have a TDP of 35W. That heatsink was meant for 80W TDP at least, probably 100W or more.
I did a load test, admittedly in my cold office, and the temperatures never climbed significantly at all. Thus it seemed to work fine. The biggest concern being movement in case it freed up a shard that then shorted something.
I'll probably do the same thing on the next heatsink. I'm already looking into another heatsink option, but it's quite possible I'll just settle on the Dynatron C32 heatsink I used in the spare host. But, maybe there is a better option out there!
This was just a lot of messing around. If I could cut it cleanly, I'd be pretty content with it. But this was not clean and was quite haphazard.
Maybe an interesting story, if nothing else?
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