3DMark 2001SE, 3DMark03, UT2003
3DMark 2001SE
The fans' DX8 favourite first.
The difference, while not noticable on the graphs without glancing at the data table, is indicative of the differing approaches both 9600XTs take in search of performance. The PowerColor goes for increased memory clock over reference 9600XT, the GeCube does the same but to a lesser extent, however it increases core clock too. Depending on whether you're core, memory or core and memory limited, one of the tested 9600XTs is always going to be faster than the other.
Look out for that trend in all the graphs, to see what the frequencies on the GeCube buy you versus the memory enhanced PowerColor.
3DMark03

The core frequency advantage of the GeCube hands it the overall win in the battle of the 9600XTs, but none of the other three accelerators on test can match the 5900XT for speed.
UT2003

Core frequency gets the GeCube the initial win, then the PowerColor takes it when we become bandwidth limited. The 5900XT takes the overall speed win.