Graphics Hardware Issue

[davidbk]

No Display Signal

Just this morning I booted up my PC and my display was blank (no signal). I have two GPUs/graphics cards. I opened up my case and tried disconnecting and reconnecting them. I discovered that if I removed one of them, I would get signal on my display. If both graphics cards are connected, no signal.

My Question

Why can't I get both GPUs to work at the same time?

Some Background

It's only been a few weeks since using two GPUs. Before then, I only used one. I bought a new GTX 1060 and I've been using it alongside my older GTX 570. Things have been working up to this incident. I've been using the 570 for my display and 1060 for GPU-based rendering for 3D.

Another useful bit of information - No BIOS Screen on Boot

Since a few days ago, whenever I booted up the PC, I did not see the usual BIOS screen (Asus etc...) It was just a blank screen for the initial boot and then everything resumed normally as soon as it reached the Windows login screen.

Power Supply?

When I purchased the new GTX 1060, I had some questions about whether I'd have enough power with my 850 Watt power supply to use both GPUs at the same time. So I'm wondering whether the sudden no signal has something to do with the possible limited capacity of the power supply. But then again, why would everything be fine for two weeks and then suddenly stop working?

CMOS Battery?

The motherboard was purchased in 2012. It's an Asus P8Z68-V PRO. I hear that the CMOS battery can die after 5 or so years so I'm wondering whether a dying CMOS battery has something to do with it?

Any other ideas?

 

[DRagor]

So both cards work but only separately? How about PCIe slots - have you tested if both slots still work?
Can you now reach BIOS when using just one GPU? If yes does it work fine?
PSU is probably ok, but one of its cables might not be, so check all PCIe cables separately if they work.
Failing motherboard battery can cause many different issues, but yours don't seem to be related. However it is hard to say definitely what can or can't be caused by battery, so considering its age replacing battery is good move nonetheless, even if it won't fix your problem.

 

[davidbk]

Thanks DRagor.

Yes, both cards work separately.

Yes, both PCIe slots work separately.

Yes, I can reach the BIOS with one GPU. It works. A while back I tried to enable Intel Virtualization Technology in the BIOS settings. The feature was greyed out and I couldn't figure out why. It's still greyed out and the only solution I could find pointed to the CMOS battery, which suddenly made me wonder whether it was also the cause for no display signal.

I will check the PCIe cables. They worked on both cards at the same time yesterday. What would cause them to suddenly stop working?

 

[DRagor]

Everything can stop working suddenly. We need to exclude typical causes, and failing cables is one of trivial but possible problems. Next step after checking cables is install both cards and once the machine boots try display outputs on both cards - maybe Windows got 'lost' and don't know which card is supposed to provide display.

 

[uppercut4u]

You cannot run 2 different models/2 different gens at the same time in one system. Each model has its own specific driver.

 

[davidbk]

Thanks DRagor. I'll be opening up my case again when I get the new CMOS battery. I'll make sure to troubleshoot all angles and display ports and report back if there are problems.

Can I stop worrying about the power supply for now? or do you think I should upgrade to 1500 Watts?

 

[davidbk]

uppercut4u, if that's true, why were things working fine in the preceding few weeks? and suddenly stop working?

 

[DRagor]

Assuming it is quality unit, 850 W is definitely enough for those cards.

 

[davidbk]

Ok I just opened it up and replaced the CMOS battery. I checked and made sure all the cables were secure when putting it back together. Both GPUs are working great now!