[citation][nom]energy96[/nom]I fail to see why anyone would ever really care about this in a desktop setting. The only advantage I see is a small power savings in 2D mode where most discrete cards already have a fairly small consumption rate anyway. If it were even $50 a year I would be surprised. I didn't even see any difference in my already small electricity bill when I added SLI GTX 580's to my system. On battery power? sure that's great, plugged in to the wall? /shrug who cares.[/citation]
Switching off the discrete seems to pose multiple benefits.
1. Less electricity expenditure, which is the most obvious.
2. Less system idle temperature, I would think.
3. Possibly a longer video card lifespan, as well as for its fans. This is taking into account how a lot of people use their PC's for a lot of none graphically intensive tasks meaning a lot of time having electricity passing through the video card and fans motors spinning.
4. Actually getting to use that, in many cases, unused/useless IGP on Sandy and Ivy Bridges. This could be up for debate in terms of affecting CPU performance though as it could, in some cases, impair Turbo Boost dues to temperature constraints as I've read before.
5. Also, like techguy911, said above, to be able to utilize QuickSync with a discrete GPU if ever you do. This was one of the original objectives (or advantages) I believe.