Saw this and decided to register, just to make a comment about the 790 and 890 FX boards. I had the same issue happen with the EPS connector shorting out, about a day after dropping in a 1090T (previously had a C2 965BE). It sent a surge to the chip for a few seconds, and temps spiked at 65, then everything shut down (PSU went into protect).
I didn't RMA the board because I had already RMA'd it once, and didn't want to spend another $30 for something that might break a third time.
The issue with these boards is not the advertised 4+1 phasing; that is a myth. Each DR MOS is itself a dual phase chip with a controller built in as well. The design itself is fine, and the engineering is sound. Why do they blow? Simply because the heatsink is not making contact with them. They do run hotter than conventional MOSFET arrays because they are passing more wattage and overall have less surface area.
When I took the heatsink off my 790FX-GD70 I notice that one of the MOS chips (2nd closets to chipset) had never made contact with the heatsink, overheated, and actually put a bubble on the back of the board. The problem is in the heatsink design as it's not only using the thick rubber-like strip to mate chip to heatsink, but the heatsink is actually sitting cocked on the northbridge chip, as well as the MOS chips. The rubber-like strip can only do so much, and there really isn't a lot of downforce on the whole thing.
I suspect MSI knows about the issue because the first time I sent my board back (due to a locked BIOS that refused to reset after a week of no power/battery/with reset jumper shorted), they returned the same board, but the heatsink had obviously been removed to check for damage, so I'm guessing it's routine. Granted, the board ran like a champ, but voltage did fluctuate a tad.
The UD5 890FX board I bought has zero fluctuation, running 1.296 (instead of 1.300) volts at any given load with all 6 cores running 3.6 Ghz. It's not a big overclock (some wouldn't even call it that) but will suffice for now. I like MSI boards in general, and have used them in the past (along with other products) with no errors. This board, however, is flawed, and MSI's RMA process stinks (agreeing to pay shipping to them for something they obviously know is flawed). Granted, the Gigabyte isn't without its issues (F1 bios was flakey) but those are being addressed. My only gripe with that is seeing the NB and VRM section running in the 40C area...too hot for my tastes (My processor hits 41C after a few hours of Prime with 6 threads running...go Noctua).
Hopefully this will help people, and get the word out about these boards.