Cpu and any other heatsinks in the machine.
Build it by myself in 2012 never have a problem and now this happens few weeks ago and still. I have check everything except the AMD micro and the ASUS motherboard. The others component work fine in another PC. First I thought was heat issue because it seem to help withe a fan on top of the factory Micro Fan but it restart more when load in the CPU increase i have not more idea what could it be. Help!!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic