Really thanks for the efforts of gnif and verybigbadboy
However, since I have a EVGA GTX670 with the same PCB layout like GTX660Ti
So I need to find the modification by myself and here is the result.
For the 4th digit, as everyone already knows, it is right on the position of resistor 1 and 2.
Depend on which card you have and you can remove resistor 1 and change it to tesla(40K), grid k2(40K) or Quadro(15K) on resistor 2.
For the 3rd digit, it is the tricky part.
As the low byte on the top side of the PCB with resistor 4.
You don't need to do anything for Tesla K10.
However, if you need to change it to a Quadro K5000 or Grid K2
You need to remove resistor 4 and install resistor 3 "MANUALLY" since no place for resistor 3 any more in the PCB of GTX670 and GTX660Ti
As you can see in my attached bottom side photo for the "rework".
You need to connect to EEPROM pin 6 with a 20K Ohm and pull up to VCC.
My rework is quite ugly but it works fine!
Please be careful and take your own risk for modifying your card!!
Summary
GPU Name Resistor 1 / 0-7 4th byte Resistor 2 / 8-f 4th byte Resistor 3/ 3th byte (high) Resistor 4 / 3th byte(low)
GTX 660Ti 20K None None 25k
GTX 670 None 10K None 25k
tesla k10 none 40K None 25k
quadro k5000 none 15k 20K none
grid k2 none 40K 20K none