1. 110c on a GPU core is flat out bad. Who the fuck is arguing otherwise? TJMax is a whole different story from recommended temperatures. It's like a traffic sign reading 100 MPH on a road where clearly the preferred speed is notably lower than that.
What the heck do you even mean about stability between 50 and 80c? You're literally not making sense, probably because you forgot "in-" in instability I'm sure, but if that's the case it's still complete garble.
2. The 3570k isn't more "sensitive" the way you describe it. What is going on with Ivy Bridge is that the temperature escalates stupid fast when you start putting a certain amount of voltage through.
3. You just listed the Tcase temperature for the 2500k and 3570k. Comparing that to TJmax is very much apples and oranges. The TJmax of the 2500k is 98 degrees celsius according to RealTemp, but that's because it starts to throttle at that point. Complete shutdown kicks in at 102c if I don't remember wrong. On the other hand, the Ivy Bridge chips have a TJmax of 105c according to reviews.
Now here's something I gotta make clear, Faithh: You don't wanna be near TJmax. Nowhere near. But when the TJmax of a GTX 680 is 110c, reading a temperature of 78c is a non-issue.
---------- Post added 2012-12-04 at 11:45 PM ----------
@OP: I'd personally suggest a GTX 670 over a GTX 680. The performance difference is negligible in the first place, and being mostly the same hardware (especially with things like the
680 PCB) lets you overclock quite casually to meet the 680 or even trump it.