So I have looked up your board and CPU specs.
The board is probably Ok. Regarding the CPU, I found some alternatives:
5750GE with better specs in everything, especially 8 cores 16 threads, lower TDP of 35W and just a little higher price, or
5700G also at higher specs, equal TDP of 65W and half the price.
My own personal choice is something different and harder to find (only on aliexpress so far): itx board with a preinstalled 5825U at 8 cores and TDP of 15W.
them actually being cheaper because they’re extremely loud apparently
Please tell us more about your design goals and priorities.
Is noise the most important prio? Would you spend money for this goal?
How about power usage?
How about price limitations?
When looking at harddisks, there is that performance issue called “CMR or SMR” (google it). Your ST8000NT001 seem fine performance-wise as the use CMR.
Source: https://nascompares.com/answer/list-of-wd-cmr-and-smr-hard-drives-hdd/
If you need really quiet ones, then maybe you want “desktop” harddisks. But many of them use SMR which limits their performance.
Raidz (1? - 1 disk failure tolerance)
Most guides recommend Raidz2 currently. Do you use backups?
When buying SSDs, check for the “TBW” spec.
I’d like to lower my power usage, if possible
40 cores of Xeon E5-2680
So there are your power whores. TDP 4 x 115 W. But they are old and very poor…
my load average is less than 1
… because nobody ever comes to visit them. Kindly give them the boot.
my knowledge of desktop technology
No worries. You don’t need to go that far :) At least don’t touch things that have “Gaming” as their firstname. Just look for some (nearly) modern CPU(s) because they are so much more power efficient, and spend some hours at https://www.cpubenchmark.net/
An example from the other end: my current server runs an Intel G4560T (35W). My next server will get 1 or 2 Ryzen 5825U’s (15W each).
How and where can this be verified? (for a not-yet-user of such a feature)