OK... so I am at a loss
From your serial number you definitely have a 2002 Quicksilver; the total production run was Jul 18, 2001 - Aug 13, 2002...
your particular unit was built in March of 2002 and sources state...
These were the first Macs to officially support hard drives over 128 GB on the built-in Ultra ATA/66 (ATA-5) hard drive bus, although reader reports indicate that the earlier Quicksilver model sometimes does so, depending on the logic board installed.
The Power Macintosh G4 (Quicksilver 2002) series is very similar to the "Quicksilver" series that it replaced -- both share an identical case design, for example -- but the Power Macintosh G4/933 (Quicksilver 2002) and Power Macintosh G4/1.0 DP (Quicksilver 2002) -- have faster processors with faster DDR SDRAM level 3 caches. Additionally, all Quicksilver 2002 models support hard drives larger than 128 GB
You also mentioned you actually checked the Logic board and it indeed is a "Rev B" QS Board which also supports over 128GB
One thing that should be noted, if you make the volume over 200GB OS 9 will not boot, so...
1) Did you make try to make a 190 GB Partition and a second partition, or did you try the entire 256 GB ?
2) Have you tried a standard IDE/PATA Hard drive (although that should not matter)
At the moment, I don't have time to check what the latest firmware for a 2002 QS is, but maybe someone else can chime in