High pitch humming sound on boot

[addiction300]

put together my friends computer last night and ran into a snag. the first time we turned the computer on after putting everything in it wouldnt post, but we realized we had forgotten to connect the pcu 4 pin power connector. so i connected it, and then rebooted the machine and it posted but we didnt have the cd to load windows in the drive at the time. a short while later the monitor just completely lost the signal, and now every time we boot the computer there is a high pitch hum that comes out and doesnt stop, and the monitor still wont get a signal

specs are:
antec 900 case
ocz 600w psu
gigabyte 965p-ds3 mobo
e6600 cpu
evga 8800gts card
2gb corsair xms ram pc6400
400g sata hd

any help would be appreciated, thanks in advance

[richardginn]

I would test the monitor on another PC to see if it works.

It would also be a good time to see if the computer will boot with the minimum of computer parts in it.

[addiction300]

the monitor worked the 2nd time we booted the system, so im almost positive that it isnt the monitor