I've been having this same issue with BSOD watchdog erorr on a x99 ws-e and two GTX 1080s. I'm currently running Windows 1709 with Nvidia driver 397.93. My BIOS is 3201, 6/17/216. I see there is an updated BIOS date 5/2/2018.
@mrpinoux we have similar systems, but I'm connected DP + DVI on just one card. So the issue still persists with my set up.
Sounds like it's worth trying to update the BIOS?