Two GPU's, Four monitors... How is this all working? Devil in details.

[RyderS]

Hello.

I had a puny GTX 260 driving two monitors... and one day I got a wild hair and added a GTX 560 Ti to the empty slot on my mobo (ASUS P5N-D), + 2 more monitors.

Now, this means that my 260 was in the "Primary" slot of the mobo,

I *assumed*, probably incorrectly, that the two monitors plugged into each GPU card, would be driven by *that* GPU. I have read that this may not actually be true.

Also, the temp of the 260, is always higher than the temp of the 560... so I am suspicious.

So... now the questions: Are BOTH GPU's working hard to display my graphics? If not, which one is? The one in the primary slot, or one designated somehow?

Should I be considering putting my better GPU in the primary slot? Why?


Next, one of my 4 monitors is starting to "drop" and Windows re-arranges for a three window configuration... this is happening intermittently.

Given that the relationship of a particular port, to a particular GFX card may not be so clear... can I assume that the cause is related to the card that the monitor is physically plugged into? Or is that assumption not a safe one?

I'm beginning to think that *possibly*, one GPU card is really doing all of the work, and just borrowing the ports of the second card.

Understanding how all of this works will be important in properly configuring my system, and troubleshooting this problem monitor.

Thank you very much for your kind expertise on this issue.

R

 

[Dextron]

In order to have both cards processing your visual information you need a multi-gpu configuration.
The only way to run a multi-GPU system with those single GPU cards is to use a SLI or Crossfire configuration, these can only be made between similar cards (eg. 560-560)

I betting one of your cards is doing all of the work and just outputting video through the other one.

You can check this by using and running a GPU intensive application like FurMark.
You should be able to see how much work (GPU Load) you're getting on each card.

Call out if need any help doing the test I recommended.

 

[RyderS]

So it sounds like only one of my cards is doing the work of driving all 4 displays, yes?

Now... so the next question is, can I choose which card does the work, irrespective of which slot both cards are in?

If not...
Should I be moving my better card to the "primary" slot on my motherboard?

There is plenty of reason to think that only one card is doing the work... however, I ran a GFX intensive demo, and on one set of monitors, I got a significantly higher frame rate (connected to the weaker card... but in the primary slot). The two monitors connected to the better card, had much lower frame rates. So that's confusing, if in fact one card is doing all the work... you'd expect all monitors to perform the same... no?


Thank you,

R