New motherboard/processor and 8 GB Ram installed.The updated rig is doing A LOT better, it has been mining with all three cards for 4 hours or so.

I know 4 hours isn't a huge milestone marker, but when your crashing every 5 mins... that's a win!!!  We'll see how it runs through the rest of the day.

In case anyone is searching forums/google for the MSI Pro Series Intel Z270 DDR4 HDMI USB 3 SLI ATX Motherboard (Z270 SLI PLUS)

I was following a rig guide on the following site. 
http://www.coinminingrigs.com/how-to-build-a-6-gpu-mining-rig/


It was relatively recent, and had comments from other users who tried the build so I thought I would follow that as closely as I could.

For me it seems the issue was the motherboard (at least thus far).  There are some other caveats though to consider
1 - The board was shipped to me in the motherboard box itself, no additional packing (ordered from Amazon).  Could that of damaged the board, maybe.  Personally I would have like to have seen it shipped in another box.
2 - BBT did do a rig build using this board, so perhaps it was just user error
3 - I varied some components from the builds (power supply selection, GPU selection)

- Your experience may vary, but just wanted to put my experience out there in case others are trying to use that board.