Here;s what you do. Do the "idiot" test for a dead system. Pull everything off that board except for 1 stick of mem, the cpu and video card. Power on the unit. Look at the keyobard when you power it on. Do you see the LED's blink once. If not, pull the video card and do the same. in the first case if the LED's blink on the keyboard you have at least gotten past the mobo/cpu test at post. If not, and you pull the video card and you get the long beep and the led's flash it's the video card. If you can get to post with all three plugged in then start addding stuff until it fails. Now, you should also do a mobo voltage back test: you should see 12 vdc +/- 5% to the ATX 4 pin connector and less that .0010 volts to the two ground wires. Test the voltages at pin 9 and 14 and the associated ground wires (20 pin---you'll need to check your mobo literalture for the correct corresponding pins if it is a 24 pin power connector). If those voltages are low the PSU needs to be replaced. If you have greater than .0010 volts dc to the grounds you have mobo circuit leakage and the mobo needs replacing. You do this with a digital voltmeter and you can pick one up at Sears for $40.
