Since it's been almost three days....I'll stick my neck out a bit?
My 4790K bought from SL too, the max temp I've ever seen and only for a few minutes when stress testing was 75C...
I don't know what speeds you're looking at? Though, you did report volts....my volts at 1.273 @ 4.8ghz for the last 18 months.
I use a Corsair H100i with the fans and pump at full speed and play a game called Insurgency (single core dependant game, heavy usage) for more than several hours at a time....I use HWiNFO64 to keep track of all temps and volts...highest temp on CPU ever...was 65C on a hot day.
You might wanna consider the same?