My WoW Classic crashes alot. I can get maybe 30 minutes of gameplay before it happens. Sometimes more. I dont know whats causing this. I’m running with a rather old PC. It has dual gtx 760. I have tried to everything there is to do online from varies of forums and articles. This is my last hope of getting my PC to work before raid. If any has been succesful of solving this issue, I’d very much like to hear it out! 
You could try with one GPU in the system, check if there isn’t any driver updates. If you have Intel integrated graphics you may also need a driver for that to mute WoW driver check as sometimes he will want drivers even for unused iGPU.
Also if it happens after some time then it may be related to thermals - something is overheating maybe (check fans, clean dust), or some power draw problems (things get hot, fans ramp up but there isn’t enough power and GPU resets causing game crash).
I have tried to disable one of the GPUs - still crashes. I’ve updated them all as well. Thermal isnt an issue as the temperature is around 50-55 degrees celcius. Also I dont use integrated graphics driver
Can you run some generic benchmark like Unigine ones to see if it will crash also? And also try physically removing one of the GPUs.
Ran benchmark test and there was no problems. Didnt take the GPU out.
I got it to work. I had to disable SLI and select the option that allowed programms to decide 3D settings. Havent had a crash for a few hrs now. Crossing my fingers it did the job