6-Way Nvidia GeForce 8800 GTS 320MB Graphics Cards Roundup
 

Surprisingly, each of the six cards could overclock its main GPU frequency to the same point, to 621MHz. A frequency range of 621-648MHz seems to be the limit for the revision A2 G80 chip. This time neither card could work at a frequency of 648MHz for more than a couple of hours.

http://www.xbitlabs.com/articles/vid...B-roundup.html