I just changed cases and power supply to a 600W up from a 400W and I can turn the computer on, but it won't turn off unless I use the switch on the actual unit. It says there is a signal from the monitor when I plug it into the computer, but it won't display anything. The graphics card isn't plugged in all the way into the PCi-E slot, but the fan runs on it when I turn the computer on.
The reason it isn't plugged in all the way is because the thing where the graphics card screws in is too high for it to connect to the motherboard, but it does click with the 2.0 slot. I am wondering if the problem is that there are 8 pins from the power supply, but only 4 pins for the motherboard. Could that be a problem also?
600W power supply.
NZXT Phantom 410 Case
AMD Phenom II
Geforce 520 2GB
Motherboard: Honestly couldn't tell you I can go find it but it'd take a couple of minutes.