Back in November I custom built a PC with a 9800GT. I'm running a dual monitor setup with main monitor being a 32 inch Sanyo HDTV, and secondary being a 19inch i-inc monitor. At the time, The I-Inc was run vga, with the Sanyo being run DVI-HDMI. Whenever I would run full screen on the Sanyo, I would occasionally get these weird green pixels, usually outlining a shape on the screen, which would appear and go away, or appear and then the TV would lose signal after losing picture. Since the card was still under warranty, I replaced it and the new card worked fine.
About a month ago, I traded the 9800gt for a 9800gtx+ with a buddy who wanted to SLI two 9800gts. The card worked great for a month, and then the exact same green pixels started appearing. The exact same symptoms, but a new card makes me think motherboard. The only difference is that the gtx+ worked great for the first month, and now the 19 inch I-inc is run dvi. The problem only appears on the Sanyo TV, and if I turn it off the problem disappears. I have never had a problem with the I-inc.
The problem most often happens when I am playing .mkv video files in VLC player, and happens during full screen video gaming, but after longer periods of time. It usually takes between half an hour and an hour during a movie for the problem to appear, but once it appears it stays, even if I turn the TV off and back on.
System Specs: Microsoft Windows 7 Ultimate
AMD Phenom II X4 945 overclocked
Western Digital Caviar 500GB HDD
Gigabyte GA-MA785GPMT-UD2H motherboard
4GB (2GBx2) Corsair DDR3
700 watts power supply
Card drivers, chipset drivers, Motherboard bios, large enough Power supply ,proper case cooling Any of these. Also test motherboard with Hot Cpu testor pro . Its test ram motherboard chipset etc very good. Will tell if your hardware is bad
First thing I checked was all the drivers, and after that I did a mobo BIOS update. Pretty sure 700 watts has it covered on power. The one thing that I have not checked is the temperature of the GPU, but I wasn't too worried about it because I have tons of fans. But I will check that while running a full screen movie and get back to you.