I saw I'm not the only one with similar issue, but I have tried everything I've managed to find in the web and nothing helps. Already stress-tested my GPU (gtx 1080) in furmark and no crashes occured, deleted and reinstalled my GPU drivers and nothing helps. And one thing, I think it started happening after installing Blood and Wine DLC and now in Toussaint it crashes sometimes few seconds after starting the game. Any clues? I tried other demanding games and nothing bad happens, so I don't think it's GPU/PSU fault.

Have you checked your GPU's temperature when playing Witcher 3? My GPU is at 80 - 84 C when playing this game. However, never encountered any odd reboots though. Maybe because the peak operating temperature is at 99 C?

Yeah, that's a weird issue. The only time I experienced odd reboots was imminent hardware failure (in my case a PSU that was about to go). Are you sure that all your hardware is in good condition and nothing is overheating?

yup. as I said I tried stress testing my computer with furmark to check if my PSU or new GPU is failing and for any instability that may occur, but nothing happened and witcher 3 sometimes reboots my computer few seconds after i load the game. other demanding games seem to run ok as well. damn, I'm out of ideas on this.

Post the pc specs.

i7 4790k, gtx 1080, 16gb ram ddr3, psu 600w. no other game behaves like that

no problems with unigine heaven as well, just tested

I get the same issue, i reinstalled older drivers (2 versions older) it now wont reboot but some times freezes or crashes the display driver...ONLY witcher 3 does this and ONLY since the Blood and Wine expansion was installed

You have a very underpowered Power Supply for that hardware kit - although you don't mention the brand... a bronze or gold rated PS would probably be OK, but if it is a generic - I'd want to do better.

Set your PC to not reboot on error, so you can see what the errors are. From what you describe - it really sounds like an overtemp or voltage issue.

True, if you have a generic PSU that came with your cpu case then you're in trouble. Just check it first then if it's not rated as bronze, silver, and or gold then I suggest that you get one even the minimum requirement stated needed by your GPU.

PSU isn't underpowered, 600 vat is easily enough for my config. It turned out my CPU stock cooler was dying and my CPU temps were reaching over 100 degrees, so motherboard was shutting down the system to avoid any damages. 4790K is a very hot chip. with CM hyper 212 evo temps never go above 60 degrees (during gaming), so everything's ok now.