I had a used gtx 980 in my pc, that 's only about 2 years old. It would reboot when gaming unless I underclocked it with MSI afterburner. About 6 months ago I decided to upgrade/sidegrade and got a brand new Radeon 580. It worked fine for about 2 weeks, then started doing the same thing the gtx 980 would do; pc would reboot when I started playing a video game. I returned the card and stuck with the 980. Fast forward to about 2 weeks and ago, and I decided to upgrade again. I bought the gtx 1660ti, knowing that it uses less power than both the 980 and 580. I figured maybe they were drawing to much power/ causing too much heat or something. It has worked fine for about 2 weeks, then it happened again; pc now reboots when in the middle of games. Any help is greatly appreciated. I'm at a loss as to what the problem is, but I figure now it may not be a gfx card issue. Thanks.