Bought a "tested" Medion ATI Radeon 9800 XL recently but found out it has a lot of artifacts. After closer inspection I found out that it is missing a ceramic SMD capacitor labeled C684 (see attachment). Photo is from vgamuseum.info btw.

As it is unmarked how can I find out the values to buy a replacement part? I think it's a 3225 ceramic capacitor (1210 imperial) and I think 16V Voltage Rating should be a safe bet? But what about other values like Capacitance and Tolerance?

Probably can measure one of the similar ones on the board or do you think they don't have the same values? I got a DSO-TC3 (oscilloscope & transistor tester) but I don't think it can measure ceramic capacitors. Also got a Kaiweets KM601 multimeter but don't know if it's accurate or even working with ceramic capacitors. Is it mandatory to desolder it for measurements or can it be tested on the board?

Not a novice regarding soldering but until now haven't had to deal with unmarked ceramic SMD capacitors. So a lot of questions. 😀