even a Pentium uses a 64bit memory interface, you didnt get it 😀
I also have the 9550 and mine works at 400Mhz clock (250Mhz default)
It uses the Same GPU as the Radeon 9600 so you can also easily raise the clock and gain free speedup.
Only Memory clock will stay behind. As the 9550 uses cheapo 200Mhz DDR Ram.
Radeon 9550 Stock 250/200:
3Dmark 05 - 682
Radeon 9550 OC 400/203
3DMark 05 - 1445
Radeon 9550 OC 450/203
3DMarks 05 - 1526
Huge Increase, no stability issues at all!
But you need Omega Driver to unlock Clock.
The ATI Driver will reset always back to default clock.
And you can use radedit and atiflash to make your clock permanent so no tools needed anymore.
Unfortunaly my Card has this Memory equipped: http://doc.chipfind.ru/pdf/samsung/k4d551638ftc50.pdf
Only 200Mhz, there are Cards with hynix Memory that have a bit more headrom and often allow up to 20-30Mhz more Memory clock.
Even some are equpped with 300Mhz DDR, and can run full 9600 Speed.
https://www.retroianer.de - under constructing since ever
https://shadowcircuit.de - german retro computer board