4 NVIDIA 7800 GS AGP Voltage Mods

We reviewed the relatively new NVIDIA 7800GS AGP a short while
ago. It is definitely a very overclockable card by just bumping the speeds up
using software means. However, seasoned users may want to unlock the overclocking
potential of this card further with hard mods to enable more voltage and current
for the card. Now, you can…

We reviewed the relatively new NVIDIA 7800GS AGP a short while
ago. It is definitely a very overclockable card by just bumping the speeds up
using software means. However, seasoned users may want to unlock the overclocking
potential of this card further with hard mods to enable more voltage and current
for the card. Now, you can…

First of all, please ntoe that all these hard modifications
to your hardware will void the warranty for them immediately so do them at your
won risk and with this knowledge!

This modifications should apply for most if not all the 7800GS
AGP out there which are on reference design as of this point of time.

Now for those relatively new to hard modifications, you are
welcome to check out VR-Zone’s mod guide.

Having said that, for those who want to go only as far as simple
pencil mods, you will be only looking at the Memory voltages.

1 NVIDIA 7800 GS AGP Voltage Mods

Figure A

As seen above in figure A, the spot to measure VDD and VDDQ
for the Memory is as marked. The default for VDD is 1.8v and the default for
VDDQ is 1.4v.

To increase VDD, you can pencil the resistor marked above.
Original resistance is 570ohms. Penciling it down to 530ohms will increase VDD
to 1.92v. Please do this carefully in small increments and measure resistance
before turning on the PC. Alternatively, you can solder a 10K ohms variable
resistor across the resistor, set at maximum resistance of 10K ohms. Lower resistance
to increase voltage.

To increase VDDQ, you can pencil the resistor marked above.
Original resistance is 870ohms. Penciling it down to 700ohms will increase VDDQ
to 1.71v. Please do this carefully in small increments and measure resistance
before turning on the PC. Alternatively, you can solder a 10K ohms variable
resistor across the resistor, set at maximum resistance of 10K ohms. Lower resistance
to increase voltage.

Try to not have VDDQ above the voltage of VDD… you can play
around with voltages in reasonable variance to see which your card likes.

Now, for VGPU, the voltage for the core speed. First of all
you should look into performing the over current protection mod for this card
before this venture as additional voltage will only trigger this earlier.

Removr the resistors marked below to “disable” this
limit. They are located beside the ISL6568 chip on the back of the card.

2 NVIDIA 7800 GS AGP Voltage Mods

This raises the current limit “allowed”.

Next measure the VGPU at the spot marked in figure A. The default
voltage should be 1.3v in 2D and 1.4v in 3D.

To increase voltage, solder a 100K ohms variable resistor to
the spot marked below, near the same ISL6568 chip:

n NVIDIA 7800 GS AGP Voltage Mods

Connect other end of resistor to any grounded spot. Set at
maximum resistance of 100K ohms. Lower resistance to increase voltage.

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