Intel Motherboards : x99 Extreme 4 won't post / erratic behavior

Yes, I definitely kept notes and numbered the individual RAM sticks on the sticks themselves so I could keep track of what worked and what didn't.  I know sticks 1 & 2, and only those 2 sticks, allowed me to post to BIOS.....once.  I have been unable to post since then, even when using those same numbered sticks, but admittedly I haven't been resetting the CMOS every time I tried booting with each of the 4 sticks in pairs and individually.

I am going to buy a couple of new sticks of DDR4 to rule out simultaneous failure of all 4 of my memory sticks.

Thanks for sticking around.  Will report back when I get home.