Airflow in Xeon Phi 3120A

[Johannes_B_]

Hello everyone,

we have 4 actively cooled Xeon Phi 3120A installed in a machine with additional cooling. However, we keep having overheating problems. We have not found any information regarding the airflow in the Phi cards - is it supposed to blow air out of the back of the case or suck air in?

On top of that, we have 4 very closely stacked cards - there is only very little space between the individual cards. Has anyone run such a setup and has not experienced heating problems or even solved them?

Thanks for any help!

[TimP]

I haven't seen that exact model, but the Phi cards I've seen take air from inside the case and exhaust outside the case.  If your case didn't have a clear path to draw outside air into the intake of each card, that could be troublesome.  I've never had a pair of coprocessors run long enough to test that aspect.

My first Intel Phi SDP had the CPU taking exhaust air from the Nvidia display card which was to be replaced by the coprocessor, and so the host CPU was overheating.  I still have that SDP; and it has failed 2 graphics cards and a Phi coprocessor.  Now it has an AMD display card.

[jimdempseyatthecove]

Try 2 cards with a gap between them. See if you have overheating. Assure that the input is not obstructed for either card.

The air goes into the round hole where you see the fan. You cannot obstruct the inlet, so 2 might be the best you can do, unless you find a server motherboard with 10 slots (every 3rd slot).

On servers, the higher card counts are achievable using the "P" series (e.g. 5110P) that are flow through. You duct the fan to the end of the card. Depending on your fan choices, you might be able to get 4 "P" series into a motherboard with 8 slots (or even 7 slots).

Jim Dempsey

[Frances_R_Intel]

Per the Intel® Xeon Phi™ Coprocessor Datasheet, in talking about the 3120A:

The blower has been designed to maximize the pressure drop capability and is able to deliver up to 35 ft3/min in an open airflow environment. When installed on the card, the blower delivers 31 ft3/min with no adjacent blockage. When an adjacent card is considered, the resultant impedance loss causes the flow rate to drop to 23 ft3/min. The active thermal solution is designed to provide sufficient cooling even in the latter scenario.

So, in theory, you should be ok but obviously you are not. I have no words of wisdom other than - try what Jim suggests but also keep in mind what Tim said. It may just be way too hot where the cards are and you might need to improve air flow through your whole system, even if the cards are not adjacent.

[jimdempseyatthecove]

As an interim fix, consider a "swamp cooler" http://www.air-n-water.com/faq-swamp-coolers.htm

There is really not much to it. This is an evaporative cooler. What you would want to do is to duct the output into the case (at the intake of the Xeon Phi's). Sears has some, so do AC suppliers. These start at about $100 and go up.

Jim Dempsey