Hello Rokamas, and welcome to BC!
The only way to find the problem is test your components 1x1. You have already exchanged the power supply, so that is done. Please continue using the integrated graphics (onboard video). Remove all USB devices, leaving the USB ports clear.
> When is the last time you cleaned the box of dust? If you haven't, open the side and check for dust accumulation, especially in the CPU fan heatsink. What temperature is your CPU running at? If you need a temperature monitor, Open Hardware is one of the best and free. Let it run diminished and check your CPU, Video and box temperatures occasionally. Overheating is a major source of random restarts.
> Now test your memory:
Download Memtest 86+ , the "precompiled Bootable ISO (zip)" file (free) from my link; burn it to a CD. Be sure your BIOS is set to CD=1st boot device, Hard Drive=2nd boot device; reboot with the CD in your DVD drive. You will see the screen appear and the testing will automatically start. When it has completed all the tests, the message "press key to exit" will appear. Any errors found will be listed, even one error means that stick of memory is bad. I suggest testing each stick separately if you have more than one installed.
> If your memory tests as good, try entering Safe Mode. Do the crashes stop or not? If they do stop, that tells us that the problem is probably software, most likely driver conflicts and we can proceed from there.
> If your computer still crashes in Safe Mode, and your memory has tested good, test your hard drive. I do not think that is the problem, but it is quick and easy and we must test everything:
Download Seatools For DOS (free) from my link; in the site screen click "Seatools For DOS" link, then accept the Eula and download. Burn it to a CD. Reboot with it in your drive. In the screen that appears, first check that SMART has (or has not) been tripped. If Seatools reports that it has been tripped that is a bad sign. Next click the upper left corner of the screen for the long test and let it run. It will notify you either Pass or Fail. This is from Seagate Corp. but will test all other drives, not just Seagate.
> Post back with the above test results.
Edited by ranchhand_, 15 December 2014 - 09:58 AM.