[tryp4vps]

...... But when i do not use it for hours or so it works fine for like many manyyy hours. Even it is up right now for 3 hours.

Of course before you send your RAM for repair, it is always better to try replacing it with another piece of RAM (if you have it) first.

But because your PC works fine after you do not use it for hours, it might be a power supply issue.

So I would suggest you to try replacing the power supply to see if it makes any difference.