The Lenovo ThinkCentre M730q trades an internal PSU for a compact brick design

What other upgradeable components does the M730q have?

The M730q is a compact little machine, and the tradeoff shows in its power delivery — the PSU is an external brick, so there’s no internal PSU to upgrade. What you can swap: the M.2 2230 Wi-Fi/Bluetooth card and the system fan. The RAM and storage are the main upgrade targets, but at least the wireless and cooling are serviceable.