PC starts rebooting repeatedly after a while

[adricris61]

Hi every one I got a emachines t 2958 wich belong to a dear friend of mine and she ask me to check it out for her,the pc turn on and load windows but after a wile 1 hs or so shut down and start rebooting by it self over and over and over and wont stop doing that I have to unplug the pc from main cord,so far already change the power supply memory sticks,clean the tower inside out just in case and every component posible,if any one can help or have any sugestions I really apreciatte it in advance

 

[Tmagic650]

The motherboard is probably bad...