The question is why do you need x570? You aren't getting much for the cost and every x570 board is going to be prone to thermal issues, you are much better off with something like a b450 board if you want to go SFF.
Because I want the PCIe 4.0. I want this PC to be able use future graphic cards that for sure, at some point, will use the PCIe 4.0.I agree with ilya, the only reason to buy an X570 is if you're going to be doing 4K or 8K video editing as the only products on the market that can take advantage of PCIe 4.0's extra bandwidth are PCIe NVMe SSD's. day to day use and gaming barely touch what PCIe 3.0 NVMe SSD's provide. really, it's just AMD getting digs and boasting rights on Intel. it's also going to be a short lived standard as PCIe 5.0 is coming out in 2 years.
so consider looking at a more mature X470 or B450 motherboard. there are a lot more options to boot!
I get what you are telling me, and you are right: I could have more and valid (cheaper) options for my build.
But I want a build that last long (which can be a problem, seeing the few options are out there for an X570 MATX).
Oh right, I forgot to mention: since it happen to do some video editing (nothing professional, just some stuff for my friends), I choose a Ryzen 7 3700X.Depends on the cpu, me personally I would not run a 3900X even st stock on a B350 board even a 3700X if overclocked would be out of my comfort zone.
Outside of Asrock and Gigabyte we are waiting for small form factor boards. If you can find a X470 Asus board, it should work for most situations you can think of. Other then that wait till Asus finally releases their small boards or go ATX.
The Gigabyte itx board has done well for Womack over on overclockers maybe take a look at that.
I was also aiming at Asus, since it seem that they have some very good thermal performance, but no MATX on sight =(