yep i swapped usb cords as well. tried the other 4 different pci-e slots . THe risers were not used for a year - would that cause risers to go bad? all hardware was working and mining before for 6 months straight with no issues. The GPU's definately work as i plug them directly into the mobo pci-e 3x16 slot. the difference is i installed a new ssd and fresh windows 10 pro install. the GPU is detected in device manager,afterburner, GPU-Z, HW monitor. the weird thing is sometimes it appears fine, but 15 mins or 30 mins later (there doesnt appear to be any pattern as to when it turns off) its liek the GPU goes into sleep mode - 0% TDP, 0C temp, afterburner settings grayed out and unadjustable. so i am suspecting windows 10 pro or perhaps a bios setting. i may do a fresh install again to see if that fixes it.

mobo is asrock ab350 fatal1ty