Thank god, I can sleep easy tonight - there are NO errors on your RAM 
Im starting to think faulty PSU too now... :s
I dont know how good you are with PCs either... I've been know to open up the PSU and hoover it all out (voiding the warranty obviously). They get SO much dust in them they can overheat.
Like arc says, open the case up and unplug everything that you do not need to play your games and try then.
Could well be your Mother Board too
Just give a the connectors a good push together too incase there are any lose connections.
Im starting to think faulty PSU too now... :s
I dont know how good you are with PCs either... I've been know to open up the PSU and hoover it all out (voiding the warranty obviously). They get SO much dust in them they can overheat.
Like arc says, open the case up and unplug everything that you do not need to play your games and try then.
Could well be your Mother Board too
Just give a the connectors a good push together too incase there are any lose connections.