That's probably not a problem with your monitor. Check your video card firstly, and then unplug all PCI cards and IDE devices to see if that helps. Then plug them back in one at a time to see which is causing the problem.
Look at
Arghagsd - this person seems to be having the same problem.
__________________
CPU: Core 2 Duo E6600 / MOBO: Gigabyte 965P-DS3 / GPU: Gigabyte HD4870
RAM: 2GB G.Skill F2-6400CL4D-2GBPK / HDD: 2TB Total HDD / PSU: Antec NeoPower 480W
Cheap PSUs - 2% of system costs, responsible for 28% of system deaths
As Sealed Stick was removed, lost or damaged, it shall be out of warranty validity.
- The "Warranty void if removed" sticker on numerous CoolerMaster PSUs.