PC Reboots While Playing Games After Upgrading Graphics Card

[shiddlepong]

I've recently upgraded my graphics card from a GTX 750 Ti to a 1080 Ti. It worked fine the night I installed it, but from the next day onwards my computer has been rebooting when I play games. Sometimes it's as soon as the main menu loads, some games I can play for ~20 mins before it reboots. It's similar to what would happen during a blackout. In fact, that's what I thought happened the first time. I've taken my PC to a repair shop and the technicians found that my HDD had bad sectors so they charged me ~$280 to replace my hard drive. I've taken it home and my problem still persists. They said the PSU and RAM was fine and everything ran much better after replacing my hard drive. My specs are as follows:

CPU: Intel Core i5-4690
Graphics Card: Gigabyte GeForce GTX 1080 Ti AORUS Xtreme Edition
Motherboard: Gigabyte Z97M-D3H
PSU: Corsair CX750

I'm suspecting there may be a problem with my graphics card, maybe it's faulty? I'm not sure, I'm a total noob when it comes to PC building. I'm hoping someone here can help identify and/or fix what's going on.

Edit: The only game I've been able to play is Minecraft. So the more demanding games are causing this issue. I've been trying to play Assassin's Creed: Origins and Rainbow Six Siege and Origins will usually crash as the main menu loads, sometimes after clicking 'play'. In R6 I'm able to start a match but soon after my PC will reboot.

 

[dontlistentome]

My first thought is it's a power problem. That's because you went from using a very low power card to using a very high power card. And games are what cause the videocard to use the most power. Minecraft is more demanding on the CPU, not the videocard.

Test this by stressing the 1080 Ti without using a game. Run a stress test like Furmark. Does it cause the same problem?

I'm assuming you installed new drivers for the 1080 Ti, and that you have the pci-ex power connectors plugged into it.

 

[sizzling]

Your psu, does it have a green CX on the label? If it does that's the old poor quality cx unit making a power problem more likely.

 

[shiddlepong]

My first thought is it's a power problem. That's because you went from using a very low power card to using a very high power card. And games are what cause the videocard to use the most power. Minecraft is more demanding on the CPU, not the videocard.

Test this by stressing the 1080 Ti without using a game. Run a stress test like Furmark. Does it cause the same problem?

I'm assuming you installed new drivers for the 1080 Ti, and that you have the pci-ex power connectors plugged into it.

Running a stress test with Furmark causes my PC to instantly restart. I have the latest drivers (390.65) and two 6+2 PCI-E connectors plugged into the card.

Your psu, does it have a green CX on the label? If it does that's the old poor quality cx unit making a power problem more likely.

My PSU is the older one with a green CX label. Despite what the repair shop said, I'm thinking that it is indeed my PSU.