Do you want to change your XFX 8600GT to a XFX 8600GTS.the process is damn easy.
here r the steps:
1-> extract ur 8600GT bios thru nibitor.
2->after extracting the bios,in the 1st page cahge core to 700,shader to 1600 and memory to 850.
3->click bootup clocks and enter the same above values.
4->in the 2nd page (Voltages) set the field 3D to 1.32V.
dont tough anything else.just save the bios.
5->create a MS-DOS boot floppy.load nvflash into that floppy,the original bios and the modified bios.
6->boot from the floppy and at the prompt enter 'nvflash -4 -5 -6 'name of the biosfile with the .rom extension''.
aftre flashing boot into windows and check device manager.it'll show 8600GTS.For more information just subscribe in the email.