Because my 280s did this rarely as-well....But never once windows loaded. It only did it a few times at random (in the post screen) But now its doing it after benches. So far no games. The only thing i can seem to relate it to is heat. in WoW these cards dont touch 70c with the fans turned up but in vantage they do. Sometimes 80c. So the best guess i can have is some how heat is effecting this. But another curve ball is thrown in. It will do it at random when i just turn on my computer in the morning. Turning it back off and restarting it seems to be a temp fix for this issue. But In order to fix this fully Im calling on someone here to help me diagnose and cure this! So any help or advice is wonderful. My current signature is were everything is set atm. Minus the 2 280s. Sold them to buy the 480s lol

i have had discolorations like this befor, it was my DVI cable from my video card. you said both you 280's and now your 480's are doing it? this could well be a problem with the cable to your monitor.

check the cable from cards to monitor and/or switch it out.

the hot air from the cards after benching could be causing an issue with the cable.

Ya! Thats the curve ball that throws me off! It even does it in the POST screen. Leaving the option open for a CPU or RAM issue. So hmmmm very true...This is what I get for buying dell...lol

Next time it does it all try my hands at the cables and connections

This used to happen with my 295 all the time in vista but has only happened once in 7. it happens when starting or stopping a game/bench or other instances that change the resolution or stop the display temporarily. if you can see well enough you wont have to reset. go to screen resolution and change it to anything at all. it will clear and then you can cancel the change and be back to good

I have found that sometimes pushing the SLI ribbon on too far can cause this.  Try pulling it back just a hair and see if that doesn't resolve your issue.