Installing PCIe 16x graphic card into XServe

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Installing PCIe 16x graphic card into XServe

I would like to install another graphic card into a new to buy XServe next to the onboard graphics.

Theoratically, the size dimensions of a standard NVidia GT 240 should fit in physically. Also, I don't think the heat would be an issue. But what I've read in the installation guide, seems like a problem:

"
About PCI Express Cards for the Xserve
The Xserve accepts cards that meet these specifications:
- x16 PCI-E cards
- 6.6 inch maximum length (slot 1), 9 inch (slot 2)
- 25 W maximum power consumption per card
"

According to NVidia, the board consumes about 69 Watts maximum. Which is conforming to the PCIe specs (max. 75 Watts).

Thus, why does Apple give a 25 W limit? Is the power consumption the core of the problem that might be overcome by installing two power supply units? Or might it be the riser that defines the limit here?

I would really like to have more CUDA/OpenCL capable GPU's in the system, even if they are not among of the most powerful of their type and a GT 240 would fit perfectly into my needs. But I cannot risk damaging or unstabelizing the system or loosing warranty etc.

Thanks in advance!
TB

Posted on Oct 11, 2010 9:38 AM

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Answer 1

Camelot

Level 9

58,581 points

Oct 11, 2010 4:07 PM in response to T Borgmann

I think the issue is more one of thermal dissipation than pure wattage.

All PCI cards generate heat. That heat needs to be expelled and due to the form factor of the XServe, airflow is critical.

So it's not that the XServe only provides 25 watts of power per slot, but that anything more than that is going to add to the heat load, and that will, at the very least, cause the system's cooling to work harder and potentially impact the server's stability.

Will it be a problem for you? who knows? That depends on the environment (e.g. is the server in an environmentally controlled area? or sitting under your desk?), what other components are installed (e.g. three spinning disks will generate more heat than 1), how much RAM you have (24GB will generate more heat than 8GB), whether this is the only slot used, and more.
There's also the issue of workload - the server will react differently to short bursts of high load compared to running full-tilt 24/7.

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Answer 2

T Borgmann Author

Level 1

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Oct 12, 2010 1:16 AM in response to Camelot

Thanks for the reply! Well I think the heat problem would be the best solvable one. By now, the server is planned to be equipped with:
- the dual CPU option
- 12GB RAM
- SSD drive
- 3 or 2 harddisks
- dual power supply.

Yes, there would already be some heat producing stuff in there but the graphics board comes with another active cooling - if this is a pro or a con concerning airflow is another question. At least, the PCIe card is the last in the chain of components the airflow has to cool down. Also, the server would be located in a temperature controlled environment among our other servers.

The workload would most likely not be 24/7, but should hit 100% of each core of both CPU's and (hopefully) both GPU's for quite a long time, hours at least, more liklely some days - well both, CPU & GPU wont be stressed constantly at 100%, more or less alternating though.

Thus, if you expect the heat problem to reason apple to give this wattage limit, it would be most interesting to me, if there is anybody who is running an extension card that defenitely consumes more than these 25 Watts?

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