Guide by Shamino@VR-Zone
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 noto that all these hard modifications to your hardware will void the warranty for them immediately so do them at your own 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.
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.
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:
Connect other end of resistor to any grounded spot. Set at maximum resistance of 100K ohms. Lower resistance to increase voltage.
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 noto that all these hard modifications to your hardware will void the warranty for them immediately so do them at your own 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.
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.
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:
Connect other end of resistor to any grounded spot. Set at maximum resistance of 100K ohms. Lower resistance to increase voltage.