Those load temps seem too high for the cooler and voltage you're at, but you said it was warm out so hard to say. At 22C ambient (give or take a degree or two), I was at about 72C at 4ghz with more vcore and VTT/IMC. My mobo doesn't have a QPI voltage, from what I've seen I thought that was on X58 mobos but it might be just brand specific.
Anyway, I guess make sure your VTT/IMC is what you think it is.
But otherwise, yeah, that's awesome.
Have you tried seeing what your highest turbo boost OC is? On my 750 I found 180 to be the max baseclock while using turbo boost, but I wonder how that extra multiplier on the 760 affects it.
80 is still within acceptable range. 99 is tjmax, so I am still 20 degrees away. You have to remember intel burn test is roughly 10 degrees warmer than prime95 and nothing will ever come close to hitting it. The highest I ever saw it outside of stress testing was 68 and that was also on a warm day with hours of video encoding going on. The higher the clock the higher the temps, thus 4.2 is going to be warm no matter what voltage you use. I would love to try it on water, but I dont have the money or the time really to mess with all that.
I have a gigabye p55 based ud4p. It has an option for VTT/QPI which is the same as your VTT. I have it set to manually to the stock 1.1v. I dont remember off the top of my head the other voltages, but everything is definitely set to its stock voltage, as I manually set it in the bios.
Turbo or any power saving options dont work when I set the multiplier. C1E/EIST dont work at all and turbo makes the multiplier stick to 22 no matter what the load is, thus making it sorta useless unless I wanted to push for 4.4.
Get that 5850 up to 1ghz like it deserves haha I have one with the zalman vf3000a with the stock cooler plate still on. It never gets warm at all even with a ton of volts and 1 ghz clock. Ive had it running steady for several months now.
For turbo, yes, you need to have all the power saving features enabled plus AUTO multiplier. But that's kind of the point - save power, more efficiency, and great performance. Obviously a straight 4.2ghz OC is killer, and would have to be lower for a turbo OC (hence why I said 180 base clock was the max I could get) but 4.2ghz is much more than most people would need on a daily basis - it's mostly only better for rendering, encoding, and file compression. If you do that stuff a lot then I can see why you'd keep it OCed so high.
As for my 5850s... it doesn't go that high. Highest I've had it is 985 core, but even then it beat another guy who was at 1ghz so I guess it's running nicely. But anyway, I have reference models and I switched the coolers with Scythe Setsugens for the quietness, but they don't cool the VRM as well so I'm limited by temps. Burn tests have caused BSOD when I raise the voltage (120C VRM, tho core temp is 80 or so). In real gaming it's much more stable of course. Anyway, in all the tests I've ran with different OCs, core speed made the smallest difference. For me it's not worth OCing any higher than what they're at, especially since I have two of them. They're already playing every game at max details. If I could bump the memory clocks up tho, that'd be awesome...