i dont know the maximum but.... for sure we know the a7v133 supports 12.5x multiplier (and probably higher) and a 133mhz fsb
12.5x133=1.666ghz going by amd's performance rating 1.666ghz would be athlonxp2000+
for your info the equasion is (cpu-333)1.5=Performance rating
example 1.4ghz = 1600+ ....(1400mhz-333)1.5=1600