A few random notes about power consumption for the Fujitsu Futro S740 and 920. These are both x86-64 (also known as x64, x86_64, AMD64, and Intel 64) and not ARM processers. I have moved them around a bit, but the S740 is running in a K3s cluster. The S920 have been tested with both PFSense, NFS server, docker and in a K3s cluster. Both are very interesting in their own way and for the right use cases, but I ended up using only the S740. Tested without monitor attached and with a basic household power meter.
Fujitsu Futro S920
The interesting thing about the S920 is the SATA and PCI ports and support for AVX on the GX-222GC CPU. The SATA slot is a little tricky to access but it can be done by removing the heatsink. Compared with the S740 or a traditional Raspberry box, it is a fairly big with 5x20cm. The PCI riser I used was a standard 8x flexible Cable from Amazon. Network card was Intel PRO/1000 PT FP Dual Port Adapter 10/100/1000Base-T 5767 (half size).
AMD GX-222GC (cpu-world.com)
I tested separately with mSATA, a no-name SATA disk and with a the Intel nic and did not get anything very useful out of all of this. For the SATA disk configuration, I tested with Ubuntu 20.04/K3s and as a separate NFS server. Load average was between 0.6 - 0.8 (with two cores this is a load of 30-40%). Performance was absolutely fine, but power consumptions was not so fine: 18-22 watts. Configured with the dual nic (both ports connected) and PFSense, the power draw was constantly over 22 watts. So ... too rich for me (I did end up using one of the S920 with a SATA disk as a Windows 10 PC for a friend. Nothing impressive, but silent, low-power (for a Windows computer) and cheap)
Fujitsu Futro S740
On paper not as interesting as the S920: A single m.2 (SATA) slot and one DIMM slot. That is, it. These was intended for testing/homelapping Docker/Docker swarm/K3s cluster. I ended up running a K3s cluster on these boxes - and extremely happy about it. Power consumptions is ... tolerable: 7-9 watts per box with a load of 30-50%. Disk I/O speed is absolutely fine - even with etcd. The missing AVX support on the J4105 is a bit of a drawback. mongoDB for example requires AVX instructions.
Intel J4105: ((cpu-world.com))