I've spent hours trying to figure out exactly what's wrong with my setup, and I think it's my graphics cards. I have 3 GTX 470's (not currently in SLI, but capable), and they all have the same problem: my colors look pale and crappy. I've spent quite a while trying to mess with the TV settings to get it working properly, but I've been unsuccessful.
My TV is a brand new Samsung 46EH5000, which I purchased on Black Friday. It has the most up-to-date firmware (actually one newer than on their website). I've tested various HDMI cables and they all have the same results. I've ALSO tested two different laptops with the same HDMI cables and the color looks perfect. It's only with my computer, so I'm thinking it's the graphics cards. There is no PC mode on my TV. I've tried using a DVI>HDMI adapter on the cards, too, with no change in symptoms. My Xbox 360, using component cables, has no color problems.
What the hell is the deal? I have a hard time believing that all three of my graphics cards, which I've purchased at different periods of time, all have the exact same problem. Is there any way I can fix this? It's painful to look at my TV right now.
I think I figured out the problem after doing much more Google searching, and concluded it's the TV after all... I had to "name" the input to a PC input and everything came out MUCH better! I think all I need to do now is tinker with the color settings a bit more.
Menu > Input > Edit Name > then I clicked on HDMI1 and selected PC, with DVI PC doing the same thing. The TV flickered for a moment and adjusted to handle the signal.