My top SLI GPU isn't the primary GPU

Raven A

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Feb 2, 2015
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I have just installed a new graphics card to accompany my old Galax (reference build) GTX 970: a Gigabyte Windforce GTX970. They work very well together, and they both get to 1400MHz (OC) with a normal SLI sync when benchmarking.

The problem is, however, that even though the Gigabyte card is called GPU1 and it's installed in the top slot, the Galax card, called GPU2, is the primary GPU. HDMI/DP cables will only work when inserted into the GPU2, and the GPU2 is the card that boots. GPU1 only turns on when its image processing power is required for heavy games and benchmarks and such. Otherwise it sits idle at 135Mhz.

I want GPU1 to be the primary GPU, because it has a better cooler, it's quieter, and because it has more ports. How can I change the primary GPU?
 
I hate to say it but have you tried switching their physical positions on the board?

I'm not a SLI expert, so I'm not sure how this will directly effect performance as far as the two slots are concerned, but it might get you something.
 
Unfortunately swapping the cards didn't do anything: The Gigabyte card would become GPU2, but would also function as GPU2 should; prioritizing GPU1 in the top slot.

A couple of other things have been happening too:
One time, in the middle of a game, the Gigabyte card was suddenly limited to 540Mhz, resulting in a massive framedrop. It did not exceed 540Mhz until I removed the card from its slot and put it back in.

Another thing that keeps happening is that the "Primary Display" setting in the BIOS keeps resetting from Auto/PCIE to CPU integrated graphics. When I start the PC up with the HDMI cable in my 970, I won't see the "Press F2 button to enter UEFI" screen with the big ASUS logo (I can only see this with the iGPU). As soon as Windows is booted up, however, I get an image from my 970s.
 


Unfortunately not. I think it may be a problem with my motherboard (asus z170 pro gaming) or its bios. I have since bought a new pc case, in which the gigabyte card stands vertically, and in this position it needs to be GPU2, so I don't need it to be GPU1 anymore. I have a program which makes the fans run at 10% when at idle so it seems as though it's working when it's not, but that obviously is not a solution to the problem. I hope you have better luck in finding a solution.
 
Did you ever try disabling sli then plugging ur display into the top card, did you get a screen then? After that did you reconfigure sli and maybe it would’ve reset which card was primary. Also make sure physx is the card you don’t have ur gpu plugged into
 
So I figured out the solution as to I was having the same exact problem. What you want to do is UNINSTALL all nvidia completely. (Videos on YouTube of how to properly uninstall and what order to uninstall in). Then after it’s all uninstalled you unplug all your monitors. Then COMPLETELY power off everything, even your monitors. As well as power off the switch on ur spike bar. As everything is powered off plug ur monitors where you want them(preferably the first gpu, gpu(1)). After everything is plugged in where desired wait a minute or even 5 minutes. Then power everything back on. Should work after that. All you have to do now is go back to nvidia and do a clean install and you’ll be good.