Forgive me if I leave out an important hardware component, or I forget to mention anything, I know very little of the inner workings of a computer. I've never put a computer together, but I'm capable enough to put in GPUs, RAM, Sound Cards, etc. etc.
So you've been forewarned - any other terminology that you might use when answer my question, please assume I know next to nothing about it, and please give a brief description.
On to my problem:
About, oh...6 months ago, I experienced my computer randomly cutting off on it's own. At the time (it was a good enough guess for me), I assumed it was the Power Supply, so I ordered a new one. Forgive me if I can't recall what brand type I purchased, but I do know that I upgraded from a 500w to a 700w. This seemed to do the trick, I was happy, I didn't think nothing more of it.
A couple of months later I upgraded from an ATI Radeon 5870 to the Nvidia Geforce GTX 670 because the Radeon apparently couldn't handle Skyrim, and I figured it was time for an upgrade. Still no issues.
About a month ago, I noticed one day as I was turning my computer on, a rattling sound. Now, because of my troubles with the Radeon and Skyrim, I had taken to just leaving the side of my case open for easy access (I thought using a house fan on the card might help - it didn't), so I tried to pinpoint the rattle.
I checked the PSO fan first, it sounded like it was coming from that direction, but I couldn't see where the blades were scraping against anything. The system fan was right there on the back of the computer tower, so I could see it clearly, it was fine. Praying that it wasn't the brand new 430 dollar GPU I just bought, I checked it too, and to my delight it was fine.
I gave up, powered down the computer, crossed my fingers, and hoped it wouldn't do it again when I rebooted. It didn't. Shut down again and restarted, still no rattle. I shrugged it off and went on about my day.
Fast forward to last night. I come home from work to a repeat of the problem I had with the computer shutting off on it's own. Now, I know there are ways to go about checking your PSO to make sure it's working properly and what not, but I don't have the tools at my disposal, and I've already ruled it out as the suspect.
I started browsing many forums and sites like these (through the power of mobile internet) trying my damndest to figure out what the cause of these shut downs were. It didn't take me long before I see someone recommend downloading HWMonitor. Which I do.
And....then I find the cause of my problem. My CPU core temperatures were reading between 95C and 99C. Other posts recommended getting a canister of air and giving the inside of the computer a good once over, which I did. Every nook and cranny, removed the GPU, removed the RAM, sprayed in their respective slots.