It's not a problem of compatibility, it's a problem of scalability or how far game developers were able to think.
Most stopped at 4 core/8 threads, some may have optimized to 6/12 to cover the exceptionally horridly priced Intel sixcores.
As always with introduction of a completely new platform and CPU design there are several problems to resolve, especially in Software. Motherboards/Bios already work better than on initial release, Win10 should have received an update to properly handle or disable Core parking on Ryzen (disabled on Intel) and to its sheduler so it assigns worker threads to physical cores first + to keep threads within the same Core CompleX, etc, etc.
Time will show that no one with an open mind regarding CPU performance should buy 4-cores for higher-end gaming anymore.
I've been doing a lot of testing w\ my Intel I7 5820K 6-core CPU, even though it isn't an AMD Ryzen 5 1600X CPU, it is a very good comparison as to the issues that Denniss has posted concerning a Ryzen CPU as both of these CPU's (this also goes for Ryzen 7\I7 6900K as well) are gonna suffer from a lack of scalability\usability from the typical gaming software being used as most of this software was optimized to be run on a max of 4 physical CPU cores....HT\SMT aside. All HT\SMT does is ensure that the 4 physical CPU cores are FULLY utilized (this is the job of the OS) as the current batch of gaming software is concerned as most gaming software isn't very multithreaded capacity-wise as there isn't much that can be multithreaded code-wise due to the makeup\nature of most games, meaning they won't take full advantage of a CPU equipped w\ more than 4 physical CPU cores equipped w\ large L3 caches & fast, wide interconnect branches.....much less w\ HT\SMT added on top of it. AHIII is 1 of the few exceptions in which it does create multiple threads from a single process but I can show you that even AHIII as it's currently coded can't keep the 4 CPU cores busy enough under a greater than typical game load (default in-game settings) to prevent them from occasionally going into low power states (sleep mode) that I have set CPU affinity\priority in the OS on my I7 5820K CPU....that is also not using HT as well, due to lack of sufficient CPU core usage (the game is running on these 4 CPU cores exclusively w\ all else running on the other 2 CPU cores & even these 2 CPU cores do not get utilized enough to keep them from going into low power states). On these type CPU's when gaming is concerned this action causes a LOT of CPU core latency issues from having to wake CPU cores back up when threads are given to them when in this state & when you add HT\SMT into the mix you will cause some more latency thru the OS thread schedulers trying to determine which CPU cores are the physical 1's vs the logical 1's so that they're used properly AND which CPU cores to PARK due to lack of use & UNPARK when needed, because the Win OS thread schedulers use a token ring philosophy to assigning threads (round robin approach starting in numerical order....Core0, Core1, Core2) even more latency is created by the OS schedulers switching threads across the entire SMP structure instead of staying w\ the CPU cores close by (from CPU core0 to CPU core5...as the CCX issue is on Ryzen CPU's, just not as severe) which ends up making more thread duplication in the L1-L2 caches which the OS spends more time cleaning this up to prevent drawbacks, contentions, etc which causes more CPU latency. The list can go on...................
This excess CPU latency is the main issue IMHO for these types of CPU's running game software, and at this time the only remedy that I see, until the OS's are revamped to better handle these CPU's when under lighter threaded loads and game softwares are written to make more efficient use of all the "extra CPU cores past 4", is for a user to apply CPU core priority\affinity w\o using HT\SMT on these types of CPU's to "make up" for all this.....I can also show that this does work & work well w\ my Intel I7 5820K 6-core CPU & I firmly believe that the very same type results can be gained w\ AMD's Ryzen CPU's when handled in the same manner simply due to similarity in concept even though there are slight structural differences between the 2 CPU's.
Intel got away w\ this due to creating an environment in which they could inflate the price of these parts by designating these within a fully separate subculture of computing from the mainstream gaming culture knowing that as long as there wasn't a viable competitor that could actually marry these 2 computing subcultures (gaming\prosumer) together into 1 competitive package that could provide good performance in both subcultures at a competitive price\performance bracket, they didn't have to & folks would pony up the moola..............
AMD, whether you like it or not, has just busted this wide open w\ Ryzen CPU's on the AM4 socket....a single socket platform that will support the ENTIRE consumer computing spectrum....from entry level APU's to full blown prosumer usage...including enthuiast level gaming within this spectrum.....for similar\less costs than an Intel Zxxx mainstream platform costs. Intel cannot compete w\ this outside of it's vast mindshare advantage & they know it.
With the advent of the X299 platform Intel will now "fix" what they already should've fixed earlier starting w\ X79 forward......due to AMD's success w\ Ryzen in spite of the small hiccups w\ it & it wouldn't surprise me at all to find this X299 platform suddenly being equipped w\ dGPU capability in it's CPU socket to fully compete w\ Ryzen on the AM4 socket....all that is left to see is how well the AMD Raven Ridge APU's (Zen CPU\Vega GPU on single APU interposer using HBM2 mem) do on the AM4 socket...........
From what I have witnessed\learned w\ my Intel I7 5820K 6-core CPU, I definately will not go back to a 6-core CPU, much less a 4-core CPU, going forward & until Intel does better than what it is currently doing it won't be an Intel platform either when I can get a 8-core\16 thread AMD Ryzen 7 CPU that can perform in gaming on a close par w\ Intel then equal\exceed Intel in other areas of computing for less money to invest\maintain than an Intel 4-core CPU mainstream platform equivalent...................
....
Can't wait for a full, ground up, water-cooled AMD Ryzen 7 CPU\AMD Vega 10 GPU package build.....even though I'll have to swallow a Win 10 OS install on it (which I already have a legal retail version of on hand)....................
Just as soon as I get retired & receive my severance\vacation pay.............coming hopefully very soon. Along w\ a little Mopar muscle car from my youth days that I've been keeping an eye on....................
Going w\ the underdog this time around..............
My 2 cents.............