Question: Different CUDA computing capabilities on the same PC

[ET_]

Hi all. Today I received my shiny new GTX 580; as I already have an old GTX275 on my machine, I would ask the gurus of the foum the following questions:

1 - Can I have both cards mounted on the same PC (running Ubuntu 11.10 64 bit, CUDA drivers v5.00, CUDA runtime v4.10), using the GTX 580 for the hard work and the GTX 275 for light work and display service?

2 - Does such configuration lead to degradation of the faster board performaces?

3 - How should I set the GTX 580 to see it under -d1? I mean, does the positioning on the PCI-E slot influence the way the peripheral is viewed by the OS?

4 - May I experience problems with the video output?

5 - Are there other possible issues I am not aware of?

6 - Is Oliver still around?

Thank you for your replies!

Luigi

[flashjh]

Originally Posted by ET_

Hi all. Today I received my shiny new GTX 580; as I already have an old GTX275 on my machine, I would ask the gurus of the foum the following questions:

1 - Can I have both cards mounted on the same PC (running Ubuntu 11.10 64 bit, CUDA drivers v5.00, CUDA runtime v4.10), using the GTX 580 for the hard work and the GTX 275 for light work and display service?

Congrats on the 580! I don't use Linux, but I do use two cards in one PC with Windows and it all works great. 580/580 or 580/430

2 - Does such configuration lead to degradation of the faster board performaces?

None that I've seen

3 - How should I set the GTX 580 to see it under -d1? I mean, does the positioning on the PCI-E slot influence the way the peripheral is viewed by the OS?

If you want the 275 to be your primary, put it into your #1 PCI-e slot and connect the monitor. Put the 580 into the other slot. The only issue with this is the MB. Are both the slots at least 8x when both slots are full? If not, make sure the 580 is in the faster slot. The OS should see the first slot as -d0 and the second as -d1

4 - May I experience problems with the video output?

Depending on what you're doing, you may see some video lag. When I max out the 580/430, the screen jumps no matter what I do. I don't have monitors connected to 580/580 systems, but RDP is jumpy too.

5 - Are there other possible issues I am not aware of?

Make sure you have plenty of cooling for the 580 and the whole system. Also, make sure your power supply is up to the task. What CPU are you pairing with this system? If it's dusty where you live, make sure to clean the system out to keep the fans at their best.

6 - Is Oliver still around?

I heard from him a week or so ago.

Thank you for your replies!

Luigi

No problem, what are you planning to run on both cards?

[henryzz]

My guess is that the GTX275 will be 0 and the GTX580 will be 1 because you are running your video off the GTX275.
Your PCI bandwidth might be affected on some boards. Some would have 1 x16 or 2*x8 and various things like that. I don't think it make a huge difference for us. I have been thinking about putting a PCI-e 3.0 card into a motherboard that supports only PCI-e 1.1. This means it would be running at equivalent to PCI-e 3.0 x4 or PCI-e 2.0 x8.
I know PCI-e 2.0 cards can be put into PCI-e 1.1 systems in this way. I don't know whether PCI-e 3.0 cards are backward compatible that far.

[ET_]

Thank you very much for your prompt answers!

I have a core i5-750 clocked at 2667 MHz, but I usually run many different tasks on it: I am actually sieving to 20G 260 ks of mm40 at the same time, to extend the known limits for candidates of mm34-mm47 to 10.000 k... maxing out a GPU is not my first need.

My present plans are to use the GPUs for factoring Mersennes, double Mersennes and Fermat numbers, and run CudaLucas. I will also try to get GPU-ECM working, and help Paul Leyland search. Finally, I will try to enhance my programming skills on GPU.

Luigi

[ET_]

TThe board is connected and operative.

I have the GTX 580 on slot 0 and GTX 275+video outpit on slot 1, but apart from this everything looks ok.

Thank you everyone!

Luigi

[TheJudger]

Hi Luigi,

seems that I'm a bit late...

Originally Posted by ET_

1 - Can I have both cards mounted on the same PC (running Ubuntu 11.10 64 bit, CUDA drivers v5.00, CUDA runtime v4.10), using the GTX 580 for the hard work and the GTX 275 for light work and display service?

Yes, for sure.

Originally Posted by ET_

2 - Does such configuration lead to degradation of the faster board performaces?

Check PCIe bandwidth (link speed and link width).

Originally Posted by ET_

3 - How should I set the GTX 580 to see it under -d1? I mean, does the positioning on the PCI-E slot influence the way the peripheral is viewed by the OS?

This is... welll... some kind of random an unpredictable in some cases. In the past I noticed that after a driver update the numbering of GPUs have changed or even worse: From the CUDA application I noticed a numbering which is different than reported by nvidia-smi (system managment interface)...

Originally Posted by ET_

6 - Is Oliver still around?

I think so.

Oliver