I have migrated yesterday from Windows to Linux. At first, I installed ElementaryOS. After ~2mins of browsing web and setting things up, the PC froze; I had to restart it. It happened every time I booted it up. I then reinstalled to Fedora, same thing. Arch Linux, same thing (not in console, only after setting up the desktop environment). So I decided I would run MemTest86+ to see if there is something wrong with the memory. After 1 hour and few minutes, MemTest86+ froze too; it didn't work, I couldn't do anything, but the "+" sign in the upper left corner kept blinking, which was weird.
Would you have any suggestions on what could be the cause of this?