I tried 3th voltmod method
for increasing Vgpu up to 1.4 but I didn't find pencil in our lab, so I try to short between point with small zero resistance, when I finished soldering, the card did not shows any thing in the screen and it's Fan speed riched to highest value.
after this, I tried to remove the contact between points . then card works well but when I install the Driver in the windows, it's can't show any graphical image like windows desktop image. the Vgpu after removing zero resistance increased automatically by 0.036 volt.
also I try it under crossfire configuration in slave mode, but it didn't accept slave crossfire mode to. note that my soldering was very accurate and nothing in the board damaged in this work.
Please let me know your idea about this problem or probable solution to solve it.
what is the best solution for me in order to increase Vgpu in 4850 ?