The hubris of a man who has been building his own desktops for over 30 years...
I've closed the case, wired it up, and am downloading Devuan, just assuming the RAM, power, CPU, GPU, M2 disk, USB key and everything connected to motherboard will work.
When will I ever learn...
The stupid "Ugreen" keyboard/mouse splitter didn't work, which isn't a great start (even using USB C power for the sparkly keyboard, changing the keyboard to the dull one etc).
Bugger, only sign of life is a light that comes on for the CMOS (it's a 2022 motherboard that I'm finally using). Changed the lithium button cell, didn't help. Sounds like it's a PSU issue as I'm getting a sort of relay clunk sound when it switches on. I kind of vibed the PSU connections, but it might need a bit of actual thought. Ho hum.
Can't find the motherboard manual. It was there yesterday.
Now I remember why I hate computers. I just don't have the patience any more.
Grr, flaky bios wasn't recognising my external GPU HDMI port despite not having a CPU that does internal graphics. Had to connect the other DVI monitor. What a pile of poo.
Anyway...
I've enabled legacy boot (which seems to allow the mobo to pick up the GPU better) and the UEFI bootloader screen is migrating to the right... This isn't working.
Maybe it's the 2.5 gig NIC?
I'm wondering if I can put my windows 10 NVMe drive in there and dual boot, because the keyboard and mouse swapper is a dud. I'm thinking it'll get the hump because it's a different motherboard.
I could use the old one as a Linux file server, home assistant etc. But it might be slightly over-specced for the latter given I've got a couple of RPi 4s hanging about, one of which could do the job. Might be useful as a code repository for my world domination plan though.
David Penfold 
Steve Williams