3600 ram will allow you to have a better infinity fabric speed (gets you to a 1 to 1 ratio) so you get the most out of your processor without a lot of tweaking besides memory clocks.
X470 in my experience needed a few manual tweaks to get 3600, while the X570 and B550 I have worked just fine using XMP 3600 G.Skills ripjaws V.
I am however using a 2700 non x in my home server and it’s barely using any cpu running plex, pie-hole, and serving files directly from proxmox via samba ZFS volumes. This however is on a AsRockRack X470DU. The motherboard really does make a diffrence as @GigaBusterEXE has mentioned. For this platform because I was trying to make this a really “safe place for my data” (I still have physical BU, and cloud BU) I used ECC ram thats only at 2666MHz.
Can see some of my experiances on my build log here…
https://forum.level1techs.com/t/build-log-home-lab-in-a-box-first-time-trying-x470d4u-proxmox/162015/10