not sure if it's fair to make any assumption given that he has a different graphics chipset. best to wait until someone else with a 5670 and similar specs posts their results?
for what it's worth, i'm getting upper 4,000's on my Mac Pro (3,1 Octocore 2x2.8 w/ GTX 285)...with 10.6.3.
you may try OEV 3.3.1
and activate:
a. benchmark mode
b.AA 16
c.multisample 8
and post your results here .
would be interesting ...
best
s