Simple way to keep compute GPUs cool

First, a little bit of an update on my setup. After noticing it available for a good price from B&H Photo Video, I bought a second Zotac GTX 1060 3GB. And I pulled the setup out of the 4U chassis (Athlon X4 with RX 580) and replaced it with one of my 990FX boards and the two GTX 1060s. Running Windows 10 as well to allow for overclocking.

Specifications:

  • CPU: AMD FX-8350
  • Mainboard: Gigabyte 990FXA-UD3
  • Memory: 8GB DDR3-1866
  • GPUs: Zotac GTX 1060 3GB (x2)
  • Power: Corsair AX860

Interestingly, the acquired GTX 1060 performs about 25% lower than the one I already had, despite being the same model running at about the same clocks. That is why I wanted to put these on Windows 10. Overclocking just the memory by +500 on both cards brought the combined hashrate to a little north of 41MH/s.

But it ran HOT. As in climbing easily over 80C. Couldn’t last 24 hours before shutting down. So something needed to be done. Inside the 4U chassis, there isn’t much intake airflow. And virtually no exhaust.

PlinkUSA IPC-G4380S

The solution drew inspiration from the Mountain Mods Gold Digger chassis lineup (Ascension and U2UFO), which features 20-slot expansion card mounting for mounting graphics cards. But there’s something else: the cards are recessed behind 25mm (1 in) deep 120mm fan mounts. The fans are for drawing heat away from the cards. While not necessary for blower cards, it’s essential for custom cooled cards.

Mountain Mods U2UFO “Gold Digger” (Rear)

So I did the next best thing initially: loosely attached a 120mm Corsair SP120 to the rear of the chassis right behind the graphics cards. With it running at full speed. It has been a while since I had these in an actual system, so I forgot how loud they could be. The result?

So one card is holding fine at 72C, while the other is running at a nice, chilly 60C. With the hotter card being the one closer to chassis sidewall.

But with the SP120 running loud, I decided against using that particular fan and attached a Bitspower Spectre Pro to the back instead. Initially the 120mm fan, then a 140mm fan. But I couldn’t quite get the result I was aiming for, and the reason is the lesser static pressure. Even with removing the expansion slot covers for the slots immediately adjacent to the GPU coolers to allow for better airflow.

The chassis initially had a Cougar CF-V12HPB for airflow onto the cards. I switched that for a Bitfenix Spectre Pro 140mm. The fan has 120mm fan mount holes as well. And then mounted the Cougar fan on the rear behind the cards since it has better static pressure while being able to push ~60 CFM.

So that gives decent airflow into the chassis and onto the GTX 1060s with a quieter 120mm fan behind the cards pulling the hot air away. Both cards run in the low to mid 70s while mining.

What would likely allow for better cooling, since it would allow for better airflow, is sealing the inset area of the chassis so the fan is all but guaranteed to be sucking air from just the cards. Likely with thick weatherstripping or something like that. So perhaps that’ll be a future revisit of this depending on what I can find.

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