(In reply to comment #15)
> I got the results with fglrx:
> PPLL1@50Hz:     fb=23.7    ref=2    post=6
> PPLL1@23.976Hz: fb=23.7    ref=2    post=12
> 
> PPLL2 does seem to be used as it does not change. PPLL1 has different values
> than with the radeon OSS driver. What does this mean?


(100Mhz * 23.7) / (2 * 6) = 197.5Mhz

(100Mhz * 23.7) / (2 * 12) = 98.75Mhz

Maybe fglrx is using different modelines with a different display clock?  Can
you print what modes are being used with fglrx and radeon?  E.g., xrandr
--verbose.