B550 sidegrade

[catsuperberg]

Budget (including currency): $120-150 for motherboard, $20+ for RAM upgrade (i'm ok with buying used)

Country: Belarus

Games, programs or workloads that it will be used for: No plans to play anything newer on this system, software development for now, running NAS with a bunch of docker containers and a linux vm. 

 

My MSI X470 GAMING PRO died couple of weeks before, so now i have a hand me down b350 (it's a super cheap MSI board) with ryzen 3700x from a friend (with an idea that when i get new MB i gonna sell his stuff and pay him, with no need to rush though). 
I'm planning to do full upgrade in about a year from now and use this mb+cpu+ram in my NAS. 
Right now i'm looking for two things: motherboard and possibly RAM upgrade.

For motherboards i'm mostly looking at ASRock B550M Pro4, but concerned with polarizing opinions and reviews. I want to be able to overclock as much as possible for this budget (i have an NH-D15 and pretty good airflow with 5 140mm case fans). Also as it's gonna be working 24\7 (without overclock) later in NAS, better VRMs look appealing. I'm mostly concerned about ram OC capabilities (some people write that the fail to get even 3000 xmp) and bios options (as my MSI X470 kinda had a really bad bios). Also want to leave myself an option to later upgrade to 5900x-5950x (like really-really later when 3700x would be insufficient for NAS\Server use case).

With RAM, i now have on my hands 4 sticks of G.Skill F4-3000C15-8GTZB (8gb SK Hynix) and 2 sticks of Kingston KHX320C16D4/8GX (8gb), with 4 sticks i'm able to run them at 3200 16-17-17-34 (tRC 55). So my question is, are there some go to bang for the buck 16 gb sticks by now so i could have 32gb with just 2 sticks and have higher clocks (as far as i understand i 3700x should be able to run with 3600+ memory). If it's much more expensive than what i have now i'm ok with what i have, but if it's like $20-30 to get from 4 sticks at 3200 mhz to 2 sticks at 3600+, i'm already gonna sell a bunch of hardware why not do a little upgrade.