Computer randomly freezing/restarting

Hi everyone i am having a big problem, it all started when i bought my computer about a year ago and ever since i first switched it on i have been having the same problems. My computer freezes or restarts itself randomly, there is no pattern. I have taken it back to the shop twice and both times they couldn't find a problem and it didn't freeze or restart itself once when they had it. I have been looking through the internet for answers but i can't find anything that work. I really have no idea what is wrong, i have tryed changing my devices like my mouse and keyboard, i have unpluuged it from the internet to see if that was the problem, i have also changed the power cable but still nothing is working. So please if anyone has any ideas about how to fix it please tell me because i am sick of having an unrealiable computer.

Edit: Finally my computer has been fixed, after over a year of the problem i have found out what was wrong with it. To anyone who has the same problem as me try checking your RAM, it was one of the last pieces i checked but it seemed to be the problem.
 
Back