Unplugging the optical drive(s)... see if your hang goes away.
:if it does, try a different cable
Repeat with the rest of your hard drives.
Unplug all the hardware as I've mentioned in another thread, until you're down to mobo/cpu/ram, and at that point, with the board unplugged (which it would be of course, but _actually_ unplugged and not just powered down), clear the cmos (which resets all the pci-e data to the minimum config possible because you've pulled all the hardware)
:and start adding stuff back in. Your problem may or may not go away, and it may or may not come back.
How quality/new is your PSU? Got a backup?
I know the feeling. It's a shame to have to push good hardware because one piece goes flaky and they no longer make replacements. I have a i7-750 laying around with the same type of problems, although I need to spend more time investigating.
Not sure as to your intended usage, but if the purpose of the setup is just gaming, and normally just a single gpu, you're better off with a straight Haswell replacement. The only real benefit to LGA2011 is the extra pci-e lanes... which you don't need if you're not actually putting them to use.
In fact, for single gpu gaming, an argument can be made to switch to the AMD side of things, unless you're specifically playing games like Starcraft II, which are cpu hogs due to all the AI processing. I like my x79 setup, but for the money I spent, I could have simply gotten a core i7/2600 at the time and used the leftover for something else. If I had it to do over, I'd probably follow my own advice here, and either go Haswell or AMD.
If you do go with LGA2011, the new Ivy Bridge E cpu's have soldered heat spreaders, so they run cooler than normal Ivy Bridge processors... (which intel used thermal paste on instead of solder to save costs... but they run hotter)
You could always look into one of those new AMD firebreathers for us.... the FX-9590 pushes _146_ amps through the cpu socket during normal operation
(220 watt thermal envelope at 1.5 volts!!!)