Flashed the bios to the most recent version, but the Mushkin set will still not boot with Expo...they work just fine in the daily driver. Now the two sticks of GSkill will boot with Expo...wondering if running four sticks with Expo previously may have stressed something in this mb. I don't recall ever populating every memory slot on a motherboard before this one. Just to be safe I pulled all four sticks of the Tridents out of the daily and put the Mushkins back in.
Just now tried two of the Trident sticks and it did boot, but not in Expo...it accepted XMP. Expo is not even shown in the bios.
Here is the Mushkin memory in the daily...Expo displays normally in bios and is reflected in cpu-z as well. I just don't know what to think about this atm. RMA or let it ride.