I would pick another motherboard with B550 chipset and with better VRM.
I just bought an Asus B550M-Plus for my 3900x, seems OK for this CPU.
I doubt Hyper 212 EVO would be adequate for this beast CPU.
In my experience, Scythe Mugen 5 Rev. B keeps the 3900x around 75 Celsius and clocks are hovering mostly around 4050 MHz using 18 threads in WCG, while ambient temp is 22 Celsius.
Try to look for a Mugen 5 Rev. B, or something similar.
If money is not a concern, and you want to stick with air cooling, then have a look at Noctua coolers. These are absolutely high end products.
As for the RAM, look for a 3200MHz 2x8GB KIT. I personally prefer g.skill, but Kingston/HyperX kits are also awesome.

OK will look into a B550 although I had never considered going to the Zen3 but ....

The Cooler Master Hyper 212 EVO is listed at 150W TDP (by them)
https://landing.coolermaster.com/faq/cooler-tdp-and-socket-compatibility-list/


I like the kingston memory also but was unsure about how much. Kinda suspected 16G was not enough.

You have to remember that all my research was done with a Ryzen 7 3800X in mind but when it came time to take the plunge some instinct inside said go higher and I did the Ryzen 9.

So I am here looking for what others know.

Why Asus as oppose to another brand?

The case can take a full ATX motherboard. I just measured it.

It's a good thing I checked here because I did not notice the Zen 3 (in)compatibility of the B450. Ouch I would have kicked myself in the butt for that. It's not that much more money compared to the CPU price.

We shall see what the temperature will do. If it gets too close to too hot I will limit the CPU a bit while I check out a new cooling system.

With 4 cores/ 8 threads boinc + puppy64 my dedicated machine has never used more than 3.2GB running all the projects if that helps any.. If building from scratch I would go for a mobo/ram with the largest cache/buffer size.

A good choice IMO but you may be surprised by some details if it's your first Zen2 processor.


The 3900X can take quite some power. For a rating of VRMs on AM4 boards look here:
https://www.reddit.com/r/Amd/comments/c7qj5e/..._to_help_you_decide_on_a/
According to that list your board is a particularly bad choice. On the other hand, after I chose the ASUS ROG Strix X470-F because it would allow me to run a 3900X full throttle I found that I can't do that for thermal reasons. Well, I decided that a few hundred MHz more aren't worth 50% extra power anyway. Right now the processor it at 62°C running 24 threads at base clock under a Scythe Mugen 5 cooler.


Memory seems to always be a bit of a gamble but I think your chances are best if you buy two modules of 3200MHz memory, not slower if possible but also not faster, and try to stick with the board manufacturer's QVL. For the amount, look what you need now and extrapolate for more threads. If you're not sure if 2x8GB is enough buy 2x16GB, don't rely on being able to upgrade to 4x8GB even if you have the slots. 4 modules are not recommended for many types of memory.


I'd want something bigger but it could be good enough for base clock. Try it if you can. From what I've read you'll need a modified mounting for AM4.


In my experience replacing a board in a Linux system is no problem. You may need to reconfigure some onboard devices like network or sound but that's it.