I took a CPU out of one machine to put it in another, and when I returned it this problem started. The motherboard's green LED is on, fans spin up, drives spin up, and so on, but there is no video and no error beeps. It seems this is usually to blame on incorrect jumper settings, but my board (AK31R3) has only two jumpers: Clear CMOS, and BIOS Write Protection. I've fooled around with both anyway, but no deal. Any suggestions..?