Aspire TC-1660 Why am I getting sporadic hard freezing, and how can i fix it?

Right. Apologies, I forgot about this post until now. I diagnosed the issue to being my GPU (it worked fine when I took it out and it worked off of integrated graphics). Unfortunately, I cannot actually find any power supplies that would fit the case and other requirements of my pc in my country (the UK). I looked inside and I literally can't fit a different size psu in there because of permanent brackets attached to the case holding the current one in place. There is excess space, but I can't remove the brackets and even if i did, the new one would then not have brackets to hold it up (it's at the top of the case). There are some promising Acer psu's from America in sites including Acer themselves and other places, but I am not willing to pay the price since it'll also include shipping. So I've resigned to the fact that the issue is solveable, aka spend a lot of money, but I don't want to because of that fact.

I have though begun to try out folding@home on only my gpu. Since my pc doesn't crash so long as the gpu isnt too low load, I've been running folding@home for the day and it seems okay for the time being. No freezes yet. My pc doesnt overheat either even when I tried running a resource intensive game alongside folding@home (roughly around 66 degrees celsius). Given the infrequency of the freezing, I'll be trialling it all week to be sure, but fingers crossed. I'll eventually upgrade my pc and get something a little easier to replace parts for, but for now I hope this is a temporary fix. And if its not, I guess I'll put up with the freezing. My pc isnt exactly dying after all, just being annoying.