Pencil mod





1. Measure stock resistance with multimeter. Write down the stock resistance. This will be useful if you need to set your card back to factory settings.
2. Install card, turn on computer, and measure stock voltage with multimeter. (Touch the ground wire of your multimeter to the case and touch the probe to the contact point circled above). Write down the stock voltage.
3. Turn off the computer and remove the card and rub a pencil over the resistor circled above.
3a. Alternatively, install a 100K variable resistor at the point labeled New Resistor Here, with the other leg connect to ground. This resistor has 18 turns and is much easier to calibrate.
Potentiometer Trimmer 100K 18-Turn
4. Test the resistance after the pencil mod using the multimeter.
4a. Alternatively, measure the new total resistance at the point Measure Total Resistance with the multimeter, with the other probe on ground.
5. The predicted voltage can be calculated by using the formula, V predicted = V stock * (R stock / R new)
6. Reinstall the card, check new voltage, and overclock.



1. Measure stock resistance with multimeter. Write down the stock resistance. This will be useful if you need to set your card back to factory settings.
2. Rub a pencil over the resistor circled above.
2a. Alternatively, install a 100K variable resistor at the point labeled New Resistor Here, with the other leg connect to ground. This resistor has 18 turns and is much easier to calibrate.
Potentiometer Trimmer 100K 18-Turn
3. Test the resistance after the pencil mod using the multimeter.
3a. Alternatively, measure the new total resistance at the point Measure Total Resistance with the multimeter, with the other probe on ground.
4. The predicted voltage can be calculated by using the formula, V predicted = V stock * (R stock / R new). Assume that V stock is 2.0V for memory, and do now allow V predicted to exceed 2.1V
5. Reinstall the card and overclock.

Fonte
7600GS Volt Mod with Pencil Trick - Guru3D.com Forums

Hard mod

vgpu

The core voltage is the main problem because it is a mere 1.1V by default in 3D mode on each GeForce 7600 GS regardless of the manufacturer, as opposed to the GeForce 7600 GT’s 1.35V. It is due to this difference rather than to the lower clock rate that the GPU on GeForce 7600 GS cards generates so little heat that some models even come with passive GPU coolers. The GPU and memory voltages are regulated by two identical linear regulators from Intersil, ISL6549. To increase the voltage, you should solder one lead of a 10,000Ohm variable resistor to leg 4 of the chip marked in the picture and the other lead to the common wire (make sure the resistor is set at its maximum resistance before doing that!):



I used the point in the bottom corner of the PCB:



Now you can reduce the resistance to increase the core voltage (if you set the variable resistor at a resistance of 3,200Ohm, the core voltage would grow to 1.7V).

Use the capacitors marked in the picture below to monitor the voltage:



Warning! Some resources recommend using 50,000Ohm resistors to perform the above-described modification. The outcome won’t change for that, but I must warn you that the core (and memory) voltage begins to grow up rapidly after a certain threshold which is about 4,000Ohms. So, if you use variable or trim resistors with a bigger rating than mentioned above, you make it harder for yourself to accurately set up the necessary voltage. Be careful as an extra turn or even half a turn of the resistor may send your graphics card to its ancestors!

vmem

As I wrote above, the regulator of the memory voltage is identical to the GPU voltage regulator, so it can be modded in the same way: connect a 20,000Ohm resistor to leg 4 of the regulator with one lead and to the ground with the other lead (you can use the leg of the neighboring capacitor for that):



The memory voltage can be read from that capacitor:



DDR2 memory works at 1.8V by default.



Fonte

Extreme Voltmodding of the Nvidia GeForce 7600 GS DDR-2 256MB Reference Graphics Cards (page 4) - X-bit labs