X86 Recommendation - ITX, in a case

I'm in a bit of a unique situation in that I have lots of extra hardware that I need to sell or use. I don't mind using some of it to build a "WAY overbuilt" routing PC. I don't mind the extra power draw as long as it's not ridiculous and ... I like building PCs.

So, my question is, are there any gotchas I need to look out for when trying to build a PC (likely ITX) to be a router? I know I probably need an external NIC - already have one on the way.

In general, anything I need or need to avoid? e.g. are AM4 AMD chips ok? I have a spare AMD Ryzen 3 3300x which again, I know would be way overkill but I don't mind using it. Other AMD options are a 3000G or 3200G (with integrated graphics) but wondering if I care/want that. I guess it might be nice to hook up a monitor and I probably don't wanna waste a video card (that said, I have some old GT 710s or something).

I also have a Celeron G5920 I could use. Thoughts on Intel vs. AMD?

Is RAM speed important for performance? i.e. should I use two sticks (thus dual-channel) 3200/3600 or will I be okay with the oldest/worst DDR4 sticks I have (2666)? There is no question if I'm going Celeron obv. (max support is 2666).

I have gigabit down 100mb up and want to build something that will get me full gigabit (wired) with QoS. I already have APs so I'm not concerned about WiFi, but I may throw a PCIe card in the PC for good measure, we'll see.


my exp as a x86 user:

  • intel often has lower idle power consumption over desktop amd (exception maybe some thin client soldered amd CPUs)
  • older intel (4th to 11gen gen) tend to have less power consumption vs newer intel
  • mind space needs for your additional nic card
  • a wisely selected PSU does a lot for lower power consumption
  • 1 RAM instead of >1: less power consumption, speed does not really matter
  • get a silent cpu fan
  • get a nic card that does not need a fan
  • consider using it as LAN SAMBA file server as well
  • have a bios that has auto-power-on-on-AC-power-connect (most have it, but some have issues)

there are unfamiliar things, when you have not used x86 OpenWRT before:

  • by default, only 1 port for LAN is active, another 1 for WAN. The technical IDs decide about the default oder. The remaining ports by default are disabled and need to be manually enabled in OpenWRT config.
  • instead of an OpenWRT reset button you use an attached keyboard
  • you can administrate it via attached keyboard and monitor and see the boot log on screen
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...and at least compare the prices (130-250 EUR) of alderlake-n/ n100 based mini-PCs with four 2.5GBASE-T ethernet ports, which will only need 5-10 watts idle. Those quickly pay for themselves on your electricity bill.

I'd use one of those, as then you have a direct console without any additional hardware.

Speed of disk and RAM is no consequence for routing tasks. If you go wild and run enterprise IDS/IPS (intrusion detect/prevent systems), like Snort or Suricata, then maybe fast RAM becomes beneficial, but packet processing otherwise is an extremely low load workflow. Even big DNS- and IP-based blocklist processing is plenty fast on little 6-800 MHz ARM processors, so you need not worry about it.

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If I can get it to <30W which should be doable with a celeron or 3000g and no GPU and a good PSU (I have a platinum SF750)... then power cost should be pretty negligible. ~12.5cents/KWh for me so like an extra $25ish per year.

It might be waste of expensive components (e.g. PSU), at least initially, but then I'm set up to do more with it in future if I decide to as well.

I think I'll actually do it open air on a test bench rig I have that I don't have another use for right now, so at least I'll save on that instead of buying a fancy SFF PC case.

edit: just looked at the efficiency curve of an SF750. That would be a waste. Will use the best PSU option I have on hand since I'm gonna do a test bench anyway so I can go mATX and full size cheap PSU if I want. Cool.

You can buy a fanless 8 core intel i5-305 box with 6x 2.5 GbE for around $350 :

Or go for the 4 core intel N100 - I got mine for 255€, with 8 GB RAM and 256 GB

You can add a wifi card inside (and connect antenna outside), put two big ssd and as much ram (ddr5)...
It will do firewall, switching, NAS, home-assistant.. everything you want while eating MUCH less power (≈10W) than mismatched luxury parts you would put together, have no moving parts, ...

better put your platinum 750 to better use.