Video Card or Power Supply :/ I just dont know

hello again experts,
I just needed some help again figuring out whats my PC's problem, i have this computer for about a year and a month now, and now its starting to show me some problems, problem occurs after 6-7months of playing, at first it just restarts whenever im trying to update/install new video card driver, I have this Sapphire Radeon r7 360 btw. whenever I install or update new driver it just restarts every time I play games then I thought id stick to the driver that works then weeks later while using the driver that usually works, my pc suddenly restarts even when im not playing, even on stand by, so I think the cards dead so I stop using the Vcard and decided to try the on-board card. and thought its the card. so then im playing now with my on-board card, then again it still keeps on restarting some time but not like when im using my vcard.

so keeping it short, if Im using my card, my pc restarts VERY OFTEN even just after I turned it on, it restarts on BOOT,
it still restarts when im using the on-board card.

so I got this second thot that maybe its the power supply not supplying enough power for my PC.

I already tried to FORMAT, CHANGE THE THERMAL PASTE FOR MY PROCESSOR AND FOR THE VCARD,
I already borrowed my friends Vcard to see if its really the card, unfortunately it still restarts.

PLEASE EXPERTS, im going to buy new parts but I just dont know what to buy coz Im really confuse whats wrong with my PC.

Sorry for Bad english and long story.....


PS: Video Cards temp is 40c - 92c (got this via FurMark)

92 degC for a video card seems very hot to me. Maybe check your cooling. Especially extraction fan(s).
My wife has a R7-260; never gets hotter than 77 degC, even when hammering it with a very modded game.

Best way to troubleshoot your problem would be to swap the main components out one by one, using those of a (good) friend.
That said, my previous rebooting pc was the motherboard at fault.

The power supply is rarely the culprit. It mostly works, or it is dead.
(unless it is a very low quality unit)

Success with your troubleshooting.