Card clock confusion- insight needed

[filmbot]

My x850xt AGP does 580/650 in '06 but wont pass '01 till I lower to 575/650.
The thing thats confusing is I thought that my '01 clocks would be higher than my '06 clocks.
Another thing is I can pass '05 at the same clocks as '06 but '03 also wont run till I lower to the same clocks as '01.
Any idea what to do or whats wrong?

[v0dka]

What kind of instability, just artefacts? If freezing: how stable are your CPU and mem OC's?

For example, '03 was known to be tougher on the CPU than '05.

[filmbot]

My CPU and mem OC's are just fine.
Right now Im in the middle of testing every clock combo I can with each test so I can find the best for each test, if ones slower than the other I guess I cant really do anything about it.