I'm sorry but I dont have any other ideas. I've been using these - M393A4K40BB1-CRC0Q for my boards - 2 each and they seem to work fine.
I did Memtest them all together on the bench when I first got them, they worked fine for the 1/2 day they were running.
Maybe the board is bad?
On another note, I could not get the boards updated to 1.3. I was able to flash the BMC and the BIOS to 1.2 but that was it.
If its any consolation i am having issues with this board and Samsung Memory as well, i have 32 and 16GB chips, it seems that 1st pass goes fine then 2nd pass is when it starts throwing errors in the .3-.5MB range, and continues on.
Probably a bad board, i tried using it prior thinking all was good but then it hit a critical error and brought down my freenas box, (firmware updated with ASROCK and BMC updated)
Sadly this isnt the 1st time i have had issues with ASROCK boards, i should have learned from the 1st time, they aren't up-to par with Supermicro. and ASROCK's support... Just Forget about it (when i was RMA'ing a Legit board)
I got 2 sticks of Crucial 32 GB (CT32G4RFD4266) to do a final test. The board does get a bit further with 2 sticks in it, but still doesn't boot up properly. It at least shows Dr Debug codes, but then ends at code 67, which seems to be some kind of chipset initialization error. And again boots up fine with only 1 stick.
Well, I guess I'll just have to write it off. Too bad really as it is such a nice board featurewise.
The Feature-set is like Freenas GOLD but the lack of Ram support is depressing for sure...
I was just reading an article from @PigLover who mentioned that memtestx86+ hasnt been updated in years which is why chipset is UNKNOWN, and the fact the errors i get are sub 1MB might be more related to bios issues.
The recommendation was to test against Passmarks MemtestX86 free edition might be something i test as well
I've got a few of these boards and notice around 49C it will ramp the fans up and then slow them back down to normal and keep cycling which has been very annoying. I've tried to adjust the fan and temp settings in the BIOS but nothing seems to shift the cycling up or down the temperature range. Ideally I'd like to move it upwards towards 55C so the ramping never happens.
I have not tried any alternate coolers yet because they don't seem to be working well from users that have posted in this thread. The airflow over the CPU (1U case with 6 32cfm fans in the front) should be adequate.