VSync does not work

[Trard]

Alu iMac with ATI Radeon HD2600, Mac OS X 10.5.6 here

Even when switching on vsync in the options I still get screen tearing in Requiem and Black Plague.
Is there any way to remedy this?

...

I tried the Black Plague demo on Vista on the same machine, worked without screen tearing and ran more fluently with higher detail settings than the Mac version of Black Plague. Guess Apple's graphics drivers are just that bad or something >.>
</whine>