If I leave it on default XMP without changing the frequency down a step i get several failures to post followed by a boot with default bios settings used 

won't run at 3200 ...

I was able to grabe an asrock x370 gaming k4 from newegg yesterday which i want to swap it out for but notic its only able to go up to 2933 according to there documentation. this is crazy to me since the asrock ab350 gaming k4 is listed to be able to do 3200 memory speed... what is going on here asrock? 

Do i just need to wait for bios updates? this new chipset seems like a crapshoot with any combo currently

1. Set the XMP Profile (which says 3200MHz)

2. Leave everything the same except the frequency

3. Drop the Frequency to 2933MHz ..

Got a boot and dual channel mode and 2966MHz Frequency ... Guess I'm returning the RGB LED Tridents to Newegg

So the issue I am having that thoroughly confuses me is that the first Pro board I had was able to get EVGA 3200 RAM up near the 3000 equiv without crashing (crashed while running at 3200) and was able to get Corsair LED Vengance 3200 RAM up at full speed by default without XMP. But when I had to change that board out because of some odd behavior which Asrock customer Service told me to return and exchange for, the next board of the same type did not read the very same sticks faster than 2133...

The issue that prompted me to exchange the Asrock Pro Gaming Board at Microcenter was that everything was fine till it went to sleep but when it went to sleep and woke up again Debug Doctor was frozen at FF and wouldn't drop it till restart.

Anyway, now when using my exchanged Asrock X370 Gaming Professional Board, and a X370 Gaming K4 I bought for another build none of the previous RAM Modules or the new 16GB 2 x 8 GB RGB Trident Z C14 3200 Mhz kit I got will run at anything above 2133.

Instead whenever set above this speed with Any method of increasing speed on the new Bios update I get failure to boot (post) at the ram phase 4 restarts and the bios reverted to previous settings.

Ram Used 

EVGA 16GB 2 x 8 GB DDR4-3200 PC4-25600 CL16 Kit CAS 16 Timings 16-18-18-38

Corsair Vengeance Series 16 GB 2 x 8 GB DDR4-3000 PC4-2400 Kit CAS 15 Timings 15-17-17-35

Corsair Vengeance LED 16GB 2 x 8 GB DDR4-3200 PC4-25600 C16 _ Cas 16 Timings 16-18-18-36

G Skill TridentZ RGB 16GB 2 x 8 GB DDR4-3200 PC4-25600 Cas 14 Timings 14-14-14-34

All of these come up with a speed of 2133 despite XMP showing their correct timings voltage and speed, and despite the Corsair Vengeance LED and EVGA ones having run at a higher frequency on my previous board.

Mostly I'm just wondering how RAM that worked on the same board doesn't work on a different model of the same board ... Also hoping that Bios updates will soon be able to fix this problem Can someone confirm for me that should be the case eventually.

Thanks