Well, instead of loosening the timings via BIOS edit or flashing the card with the GTX timings which are too loose, I took a different tact and tightened the timings. It did not affect the memory clocks and improved in game performance as well as benchmark tests.

Timings:

timing-----------GTX-------GTO---------BJ11 ------ BC14-------Mod
tRAS------------24-----------22----------25---------22---------19
tRC-------------34-----------31----------35----------31--------27
tRFC------------43-----------39----------45----------39--------34
tRCDR-----------12-----------10----------12----------10--------9
tRCDW----------8------------6------------8-----------6---------6
tRP-------------10------------9-----------10----------9---------8
tRRD------------8------------10-----------8-----------8---------9

So, single 7900GTO @ 710/825, 3DMark05 - 12201 with an AMD dual core at 2.8 GHz.
http://service.futuremark.com/compare?3dm05=2265796

3DMark06, 6801, @ 710/825
http://service.futuremark.com/compare?3dm06=553054

COH, 1280x1024, 4xAA, 8xAF