BSD hacking new personal computer tower configuration ?

[sylvain%saboua.me@localhost <sylvain%saboua.me@localhost>]

I'm thinking of purchasing parts to an all-purpose *BSD personal computer.
My budget is ~€3000 (+1k). Ideally I would like it not too noisy while 
staying as cool as possible (I live in a studio), and dual screen monitor
(I'm thinking of one HD screen to also watch movies on and one square 
screen on the left for the console).

First thing is the motherboard, processor, and RAM. Here also lies the
bottleneck : is there a motherboard/processor combo that can host
all four BSD's and derivatives ? If I'm not mistaken, I think the blowfish
does not maximally exploit multi-core processor, so a quad core (for instance)
is enough. It'd also be great to have it without MINIX's IME/PSP,
but I know this is asking too much ! Or is it ?

Note that I live in Europe (SouthWestern France) so the stores of choice
would be LDLC, then Boulanger and FNAC. Unless I forget options.

There's a long time since I haven't proerly hacked and built my own tower,
I don't remember all particular caveats of the best optimisation. Suffice to
say the computer hacking's main use would be to compile, fetch
various things from the network (no brainer, right ?), as well as,
more touchy, embedded / RISC-V development (hence connectics).

Then I would also browse the web and use Word.

Haha. Just kidding. But I'd like to watch a movie at times and have a good 
HD screen and 5.1/7.1 speakers for that (the latter can come later).

In terms of ergonomics, I already have an all-black basic keyboard, as well
as a small bépo one, and am thinking particularly of the mechanical and 
TypeMatrix keyboards. Someone advised an incurved monitor as well as 
blue light filter. I don't know much about mices, but I have short hands (I'm 5"3).

That's it. Any advice/feedback fom what you guys use ?
I dream of those towers with just one big fan on the right.
Ideally, the whole thing would not consume much. It also needs
not to be one of those huge gamer towers while still fairly powerful.

Thank you