Hello this is my first time here and I figured this would be a good place to ask for help.
Anyways, as I stated in the title, my pc decided that it will keep shutting down on me no matter what I do. Every time I run an application (such as my web browser, steam, or any game) it will shut off almost immediately. If I'm not running anything and just let it idle on my home screen, it will stay running for a good 15 to 20 minutes before it shuts down. I noticed that if I restart the pc and log back into my home screen, then the date and time always reverts back to nearly 10 years ago on October 1st. I don't really know if this has anything to do with it though. It is a pretty old machine since I've had it since 2008. The only changes I have done with was swapping out both the video card and power supply. The old power supply had burnt up on me like 3 months ago. Since I made those changes it ran just fine up until now.
I've already air blasted everything inside, since it was kinda dusty. I checked all the fans, made sure everything was plugged in. Everything seemed ok hardware wise. I also updated my video drivers and deleted the old ones. So far... nothing has changed. It continues to shut off the same way.
Here are my current specs:
Vista 64 bit
Radeon HD7850
I7 920
3gb ram
I've never really encountered this problem before, so any help would be greatly appreciated.