maximum number of GPUs

Hi All,

Is there a limitation on how many GPUs supported on a X58 motherboard and/or NVIDIA chipset?
I would like to jam as many GPUs (for instance 4 GTX295 into ASUS P6T WS board) to drive 8 projectors/monitors and conduct CUDA programming. I don’t want spend a lot more to get a Tesla.
And for CUDA programming, could anyone suggest a solution between 4 GTX295 of 1792MB memory vs 4 GTX285 of 2GB memory? Thanks a lot.

Best,
8gpus

The first limit you’ll run into is the physical limit of how many cards you can fit into the mainboards. IIRC there is also a limit to the number of GPUs the OS can support, but you’ll have to use really special hardware for that. So for your mainboard it is limited to the number of x16 PCIe slots (and lower, if you’re willing to modify the slots and give up performance). With 4 physical PCIe v2 x16 slots you’ll get plenty of bandwidth to support 4 GPUs (or 8 in the case of the GTX 295). There should be no limitations here.

Not sure about suggesting a particular GPU solution.

Thanks, MayaPosch.

Here is the board spec.
http://www.tomshardware.com/reviews/asrock…puter,2275.html
Yes, physically I can put 4 GTX295’s. But I don’t know whether the OS and/or Intel/NVIDIA chipset would let them fly.
I have addressed similar question to EVGA. The tech support’s answer is quite vague. They do not “recommend” more than 2 GTX295’s in one box.

Best,
8gpus

http://www.hexus.net/content/item.php?item=18028

That setup has got 4 GTX 295 GPUs per mainboard. I can find no information or recall anything on any limits you could encounter.

Thank you very much. That’s a great blog with plenty information for my questions. :D

You are most welcome :)

Holy crap! That’s 8 GPUs with a Core i7. The problem with that board is that each pair of GPUs (GTX295) is limited to a measily 8x. That and I’m not very fond of boards that only offer 1 (one) year warranty.

If you can do with three cards at full x16 speed, this board might be of interest to you:

http://www.newegg.com/Product/Product.aspx…N82E16813131358

It supports three full x16 2.0 slots (blue) with an nForce 200 chip.

Alex

Thanks, Alex.
I knew there are boards have more than 2 PCIe slots. But I was wondering whether the chipset or OS would support more than 4 GPUs. The EVGA tech. staff’s answer was not satisfying. That’s why I am looking for people with experience of running >=6 GPUs. The Hexus Folding@Home blog is a great site. Unfortunately, the configuration is specified geared for CUDA. I am still waiting for the answer whether they can output 8 DVIs for rendering.

I don’t have experience with more than two GPUs. It really depends on the motherboard, as he found out:
http://www.youtube.com/watch?v=4Q1nfHJOvGY…feature=related
(same guy MayaPosch mentioned, but in this vid, he has a board that works fine, and one that doesn’t). As long as the videocards are detected, the OS shouldn’t have a problem using all 8 DVI outputs. I’ll be searching to see if anyone did it before.

Alex