To close the loop on this thread, it was indeed a bad CPU. Swapped it out with a i5-6600K and everything is fine. RMA'd and sent the CPU back to Intel. The obviously wrong headed thought that the CPU would be the most unlikely issue caused me to waste an awful lot of time and money! But, there are far, far worse things in life.
Now I'll have to decide whether or not to keep the replacement i7-6700K when it arrives or sell it to get some of my $$$ back!
Thank you all for your help!