Bought the following 4 years ago:

added an SSD 6 months ago.
Recently (like once in 14 days) my pc crashes..sounds gets blown up and screen freezes.
I think it has somthing to do with my ram, motherboard or video card.
I dont know anything about how to put them together.
Point of this pc is to randomly game no high end graphic games like Path of exile / diablo / wow / starcraft / League of legends / Guild wars
Is it worth looking for an upgrade or just play another 1-5 years untill it crashes? if its possible to upgrade, what should I upgrade?if the graphic card is the problem, it is easy changeable (but I read its still a good one)
if its the motherboard, it might be another problem (according to some guy I spoke at the computerstore)
the ram..well No idea