i am still willing to let asrock replace the motherboard with one that will support Hynix M-die at rated speeds. was assured about 1 year ago it would be fix in bios 

Then they showed me pic's of 3200mhz running on a b350 mobo "not the motherboard in question" and said it was my CPU,  Should have been a red flag :(

i was going to return the mobo then but felt i could trust asrock support. and everyone was having ram issues at launch.

tech support email has been very basic.  "try XMP, try 1 sitck, RMA,give up" same as the last few times i tried to get support.

they defend the K4 but wont support it :( , asrock keeps repeating that the K4 and Gaming x are the same and the only difference is VRM and USB.. well the Memory support is way different too but they refuse to admit that part/ QVL tells the whole story if you ask me.

Look at x370 gaming k4 QVL, the only kit rated 3200mhz is not real. its not a product. cant be found. Smoke and Mirrors.

look at the x370 Gaming-x it has 3333mhz supported. real ram kits. M-die at 3200mhz.

i will try to get asrock to replace this mobo again, Email support refused. so i call them up and got the same, might get a call back from a higher up. 

i called Newegg and they are working to replace this mother board for me,  Newegg has all the info of my contacts with asrock support over the year. i must say Newegg support is going above and beyond, its outside their 30day policy by over a year and still offered to help.

i did like Asrock for many years but after getting this bad egg of a product i feel burned. they only offer to replace it with another gaming k4 that will have the very same problems as its a hardware limitation in this Orphaned mother board. 

Makes sense why asrock removed 3200mhz ram support  from the product page in the first days after AM4 launched, Then less then 3 months later the Motherboard is End of Life and replaced with Gaming-x. 

a few minor observations if i may

rated xmp speed and timings if often if not always set at 2t for intel (ryzen tends to set it at 1t)

as xaltar stated differences in boards may well be just down to the different brands preselected sub timings (if it helps honestly i find msi bios tends to allow easier overclocking of ram for am4) this dosnt mean its faster/better it means they auto select safer subtimings, do i own an msi board ? no ! i prefered what i bought and that was asrock taichi overkill power supplies, but ive now built 4 msi ryzens for other people ,all of which have overclocked ram and cpu , but let me tell you msi tomahawks require a lot of volts to get the 1600's upto 3.8 stable,whereas a titainium was a breeze to get low volts 3.9 and 3333 cl14

whats the point ?

everything is different, brands of bios ,design of boards, its a case of see how you go

me ? well from day one (and we mean as soon as the taichi was in stock in the UK) i got 3200 ram working, bios version 2 ,what it took was a week or two and a lot of reading to get cl14 to cold boot, did it take a bios update ? NO it took time and education to get there

and now im still quite happy on bios v3.10

its still to some degree a case as it was at first

if you want top results with ram and ryzen buy the damn B dies , and that goes for any brand of motherboard b dies will do better than hynix etc