Not your scenario really but a HBA will allow you to use SATA and SAS drives. Gives a bit more flexibility on price, especially with 2nd hand SAS drives.

My drives are currently in a box supplied by wires hanging out of the PC (Server!) casing but it would look much neater with a 4 bay hot swap cage built for the purpose.

I just wish I could get the full 12 Gb/s out of the couple of SAS drives I use :o(

You may be out of luck, but doesn’t that board have onboard VGA graphics which you can use?

OMV is a web page dashboard and there’s SSH. What is the usecase for a GPU I wondered?

It needs to be controlled to make a profit. Once something you love becomes popular the bulldozers will move in.

Thinkpad T420, i5-2520M, 8Gb RAM, 2 x 1TB SATA SSD, 1 x mSATA and a mmc card. Some usb storage plugged in for good measure.

It was bought 2nd hand for children to use, then workshop laptop, eventually retired as occasional NAS space running OMV 8 (Debian Trixie).

I expect it to just work forever.