- May 6, 2019
I don't think they lied as much as they gave a conservative estimate on what you can expect. I think this is due to the variable levels of quality in motherboard designs. As pointed out above, the PCB layer count can make a difference as do many other design choices. Cheaper X570 motherboards aren't likely to clock RAM as high as the more expensive ones probably can. MSI's MEG X570 GODLIKE is the one they hit 5133MHz on. I'm sure you can get 4x DIMMs running on that thing at various speeds above DDR4 2933MHz. I simply haven't tried it and I don't know if I have any RAM on hand that Ryzen would like well enough to allow that.They lied! Thank God. ASUS just release a kick ass bios is probably the answer and really all the memory stuff is on the CPU which determines capability as long as signalling to the dims are good - why not? On the 2700 My top stable was 3200mhz, not much higher than 2933 in what AMD said, which was probably conservative. Being a T-Topology board probably helps but the new C8H is also doing 4 sticks at 3733 and that board is daisy chain - so for these speeds the topology probably does not make much difference if the traces are well done to the memory sticks.
Which begs the real question - what advantage if any are the much higher ram speeds, 3800mhz plus when you are no longer at 1:1 ratio between the ram speed and infinity fabric? It actually looks like performance goes down going over the 1:1 ratio. Sweet spot for Ryzen 3 looks to be the 3600-3733 memory speeds. So those just going after ram speed numbers, ignoring any real benefit, a daisy chain motherboard will probably get you there - most of the X570 boards except for ASRock.
In the mean time, I had a 4x4GB (16GB) kit on my ASUS Maximus XI Formula running at DDR4 3866MHz, and I decided to see if a 4x8GB DDR4 3600MHz Samsung B-die kit would work on that board as that's 32GB, not 16. It kept the 3866MHz settings and simply worked. So those are clocked beyond what they are rated for. I did some testing on them and they work perfectly. To give you an idea, I think I got those DDR4 3600MHz modules around two years ago. On my Intel boards, I have plenty of modules that work. So far the only thing I have that plays nice with X570 is the G.Skill Trident Z Royal DDR4 3600MHz kit that AMD sent with the review kit for the Ryzen launch.