I have about a 2" vertical multi colored band that flickers running through the center of the monitor. I have DOWNLOADED updated drivers, checked registry, checked to be sure everything was plugged in tight, taken the monitor to a repair PLACE who left it running for 24 hours and the problem did not show up. Then took the tower to same place and left it for a day. Problem did not show up. Device manager says video card and monitor are working properly. Repair place wanted to replace video card (over $500) on the premise that it must be that since the monitor showed no problem when left connected so LONG. If it were the video card, why would the device manager say it was working properly? Some days it is FINE and most days the problem occurs. Sony computer, FLAT screen, 3 years old. Any ideas? Thanks.Device Manager isn't always correct diagnosing hardware...
Remove the video card after unplugging all power to the machine...clean the contacts with rubbing alcohol or a pencil eraser and re-install it.
Check to see if the fan on the vid card is running properly as well.Not to mention, checking to make sure the heat sync is clean.

Does this card still have a warranty? I did check to be sure all was clean and the warranty is out on the card. The fan turns around so assume that it works properly. I will clean the contacts as suggested. Thanks.