Hi, new guy here, Um...I just got a new BFG 450w PSU to try and run my Nvidia 6600 since that is considered medium end. I installed it correctly but on pushing the power button the PSU fan comes on and the three signal (diagnostic) lights come up; 1 3 &4. My computer is an Optiplex 320, 2GB ram, Nvidia 6600. When I remove the graphics card the computer starts normally, so i dont get why it wont start up with the NEW PSU. BTW the motherboard has no PCIe power connectors. Need help soon, please and thanks in advance.