[gmx-users] GPU and aux power supply

[Szilárd Páll]

First of all, unless you run multiple independent simulations on the same
GPU, GROMACS runs alone will never get anywhere near the peak power
consumption of the GPU.

The good news is that NVIDIA has gained some sanity and stopped blocking
GeForce GPU info in nvidia-smi - although only for newer cars, but it does
work with the 960 if you use a 352.xx driver:
+------------------------------------------------------+

| NVIDIA-SMI 352.21     Driver Version: 352.21         |

|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr.
ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute
M. |
|===============================+======================+======================|
|   0  GeForce GTX 960     Off  | 0000:01:00.0      On |
 N/A |
|  8%   45C    P5    15W / 130W |   1168MiB /  2044MiB |     31%
 Default |
+-------------------------------+----------------------+----------------------+


A single 6-pin can deliver 75W, an 8-pin 150W, so in your case, the hard
limits of what your card can pull is 75W from the PCI-E slow + 150W from
the cable = 225 W. With a single 6-pin cable you'll only get ~150W max.
That can be OK if your card does not pull more power (e.g. the above
non-overclocked card would be just fine), but as your card is overclocked,
I'm not sure it won't peak above 150W.

You can try to get a molex -> PCI-E power cable converter.


--
Szilárd

On Mon, Jun 29, 2015 at 9:56 PM, Alex <nedomacho at gmail.com> wrote:

> Hi all,
>
> I have a bit of a gromacs-unrelated question here, but I think this is a
> better place to ask it than, say, a gaming forum. The Nvidia GTX 960 card
> we got here came with an 8-pin AUX connector on the card side, which
> interfaces _two_ 6-pin connectors to the PSU. It is a factory superclocked
> card. My 525W PSU can only populate _one_ of those 6-pin connectors. The
> EVGA website states that I need at least 400W PSU, while I have 525.
>
> At the same time, I have a dedicated high-power PCI-e slot, which on the
> motherboard says "75W PCI-e". Do I need a different PSU to populate the AUX
> power connector completely? Are these runs equivalent to drawing max power
> during gaming?
>
> Thanks!
>
> Alex
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