PC keeps rebooting randomly in demanding games.

[ambrotoscorax]

For about a week I switched my gtx 770 with a 980ti, and since then i get occasional reboots, but only when i play demanding games, like the witcher 3. The odd thing is that it happens randomly, sometimes i play for a while and then it reboots, other times it doesnt at all, and other times it reboots when i open up the game.

 

[clutchc]

Not enough information there. Need your system specs. But it sounds like a weak or cheap psu

 

[ambrotoscorax]

My specs are:
Motherboard Gygabyte B85-HD3
Power Supply Corsair VS650
Intel Core i7 4770 3.40GHz
GTX 980ti
8 GB RAM single-channel
120GB Kingston SSD
1TB Western Digital HDD

 

[clutchc]

It might be a combination of a marginal and low end PSU and the hi-demand GPU. The 250W 980 Ti requires a 600W min for normal use. And the Corsair VS, while having a sufficient +12V rail, might be aging and/or failing. Although, the 230W GTX 770 is nearly as demanding as the 908 Ti, so that may not be the cause. But try the 770 back in for awhile and see if the problem still occurs.

Was the card bought new or used? If used, it may be malfunctioning.
But I still lean towards the PSU.