ECC RAM always helps in the long term,
It helps yes, but for a router I wonder if it makes a significant difference.
if the board is collocated
It's in-house.
but I'd not have IMPI& serial BIOS (out of band) access.
Both of those aren't necessary for this project.
If you want to use X,
Always consider a spare monitor& keyboard attached / around the system just in case.
We don't need X, but do need local console / KVM.
It will need a case fan (or two for redundancy) because the CPU is fanless and produces enough heat (about 15-20 W TDP) and even without a Radeon added (20 W more) inside, the system can not rely on free air convection in a tower / desktop small form factor (mini-ITX) case.
Don't use external brick / micro / pico type PSU units, those are not offering any benefit over stock SFX/ATX form factor and are less than reliable to say the least not mention interchangeable. The PSU is one of the least reliable system blocks.
The reason I'm asking about Atoms ITXs in the first place is that physical size is a major constraint for this project and a micro ATX case or larger is a non-starter. It's even proving hard to find an SFX/TFX case that's compact enough (and isn't shit). We're pretty much looking at some sort of "open mesh" compact case design with a compact PSU, like a pico+MiniBox M350, Antec ISK110, or Silverstone PT13B + a thin-ITX motherboard with bult-in dc power. In such a cramped situation the low heat output of an Atom seems a better choice than a full sized Core. (See my other thread on this list about using NICs with multiple jacks).
Also, you're the first person I've seen who's said that pico's aren't reliable. We have one that's several years old that's still going strong. I'm curious what your experiences have been?
but you'll miss the chance to learn and use the advanced capabilities or more reliable components on board.
That's not really an issue, we have and use Supermicro stuff all the time. In fact there's a couple old P8SCT-based 1U severs I'm trying to sell off as we speak.
and don't buy used
That's a given.
There is absolutely no point in considering SSD for this system.
Maybe. This system also needs to act as a PXE boot server for a variety of clients, so it needs several gigs of storage space for all the images, and that storage needs to be fast enough that the clients can boot in a sane time frame. I'm not sure if random 16gb thumb drives will really cut it.
