Hi folks, I’m considering setting up an offsite backup server and am seeking recommendations for a smallish form factor PC. Mainly, are there some suitable popular second hand PCs which meet the following requirements:

• fits 4x 3.5" HDD
• Smaller than a regular tower (e.g. mATX or ITX)
• Equipped with a 6th of 7th gen Intel CPU at least (for power efficiency and transcoding, in case I want it to actually to some transcoding) with video output.
• Ideally with upgradeable RAM

Do you know of something which meets those specs and is rather common on the second hand market?

Thanks!

Edit: I’m looking for a prebuilt system, such as a dell optiplex or similar.