So i just put together my first PC, ASRock 770DE+ motheroard, and a Athlon II x3 450 Rana CPU... It was working fine with 4GB(2x2) for a week till today. It has a PSU that came with the case that is a Cotegen Dual 500W if you want the model number thats fine but I was swapping out some RAM today and trying to see if I could add a set of 1gb stick for a total of 6gb.. they are both PNY brands and the only difference the 2gb set would run at 400Mhz i think or something like that and the 1gb set would run at 333ghz? but i did try putting both in there at the same time and it booted up and ran and when i went to shut down my whole comp froze on the desktop and didnt do anything.. so i manually turned the PC off and took out the 1gb set and put back the original 4gb... and no my PC has no power at all. I plugged it into a diferent outlet and when i hit the power button the CPU fan spun for a quick sec and then stopped but the front LED light has not come on at all.. anything else i can try or am i forced to buy a new PSU? DO you think I screwed up my motherboard? O and im also running a HD4350 which hardly takes up any power at all.. this really sucks though because my new video card will be here tomorrow. so im pretty bummed now any advice or somethign else i can try would be great.. thanks.