Building my First SFF/S4 Mini and need help

Some Rando

What's an ITX?
Original poster
New User
Mar 16, 2023
I have built many PCs and a server but SFF/ITX is all new to me and this S4 mini is definitely more complex than other ITX builds but seems amazing and exactly what I need!

I plan on building it with either a 13900KS* or 7950X3D. I will be running custom settings and undervolting and a bunch of other stuff to make it very efficient. So, I can get fast single thread but also massive multithread by running the CPU undervolted and at like give or take 2Ghz or whatever I can get away with for peak multithread without overheating/draining too much battery power. I am currently debating on using the Noctua NH L9I with more powerful fan or possibly modding the case and using a slightly larger cooler+. I will eventually be adding an RTX4050 or something like an A2000 (or whatever is its replacement).

*I might try to get a 13900K ES chip because supposedly the engineering samples have working DLVR, which would offer huge power savings with what I intend to do.

I plan on using this for 2 things. 1) My HTPC in my room and 2) using it as my mobile stream box for my future content creation. I will be streaming using 4G/5G internet and using a multi kilowatt hour LiFePO4 battery pack.

I have several questions and was hoping you all can help and point me in the right direction. I am open to suggestions and happy to be proven wrong:
1) is there a good build guide that breaks down barney style on how to build this and what exact parts I need to buy that don't automatically come with the case?
2) I planned on not doing a "brickless" build (PSU inside case). It's just added weight and complexity and I don't see any major reason on why I should go that route.
3) can the HD Plex accept multiple voltage ranges? As mentioned above I plan on doing outdoor content creation so I will be running this off battery packs at some point in the future. I was originally going to use one of these PSUs for my ITX build but that HD Plex offers much better power and performance. But I don't know if it can handle variable voltage ranges from running on battery power. If I have to swap out PSUs when I am out doors on battery power that's not a big deal. I just need to know how this works and what I need to buy.
4) Do any of you have recommendations on what motherboard I should get?
5) Am I missing anything? Any suggestions? Besides a guide/shopping list I need to buy/build this?

+These are some interesting fans I have found and might be good if I mod the case to support them. Please let me know what you think. If you have recommendations please let me know.

1) Noctua NH-L9x65

2) Noctua NH-L12S
This one looks super promising and the fan actually stays inside the case or well at least behind the heatsink. So, you don't need to worry as much about something getting into the fan. Anyone use this one or know how much TDP it can support?

This looks interesting but I could see this being a turd.


This also looks promising. Similar to the NH-L12S but much shorter and only would stick out by a little.

6) Thermalright AXP90-X53