No repeated beep, just the standard beep? Means it's booting but not displaying. Make sure you have the monitor plug in the right slot. If it beeps low. then stops. then beeps low. then stops. This is typically RAM. Make sure it's seated. Also, try clearing the CMOS. remove the battery, hold the power button for like 15sec, either jump the CMOS reset header or hit the button. Pop back in the button-battery. Also, like badge says, make sure you've only got the proc, a single ram, and vid card hooked up.