2 possible solutions.
First and most likely, your 300 w PSU can't handle the additional ram.
Second, go to your bios and set the voltage of your ram to 2.0v. It should be on 1.8 or something now.
The pc you described isn't good and surely not worth giving up your ps3 for.

PSN name: Gazz1979 (feel free to add me, but please put your Vgchartz name in the message!)
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