Nvidia 8800 GTS reference PCB 320/640 MB G80

[der8auer]

Nvidia 8800 GTS reference PCB 320/640 MB G80

 

Pics of the card:

 

 

 

 

Mods:

 

 

You might find it to risky to read voltages at those places, if you slip you might indeed damage your brand new VGA card. Therefore we soldered 2 wires on our card which are much easier to touch during our overclocking article. We used a small tip of glue so that the wires stay in place, this might avoid accidentally contacts between each wire.

 

 

 

GPU Voltage Modding

 

 

 

For the GPU core voltage mod we must search for the Primarion PX3540 PWM IC. The resistor marked in blue is the one you need to shade with your B2 pencil. Strike it a few times and measure how the resistance changed, you can check resistance by holding the red wire of your multimeter to the red point and the black wire of your multimeter to the pink point.

 

The stock resistance measures around 35 Ohm, this is very low and this will make it very hard to pencil mod the GPU core voltage, we recommend doing the soldered modification. For the solder mod we used a 1kOhm adjustable resistor (often called VR) and soldered it between the red and pink point. This changed our stock voltage from 1.3V to 1.33V. To further increase voltage we must lower the resistance of the variable resistor, before you power on your system always make sure that your VR is set to highest value. For 1,4V we adjusted the stock resistance of 35 Ohm to 29 Ohm.

 

MEM Voltage Modding

 

 

For the MEM voltage mod we must search for the ISL6549PWM IC. The resistor marked in blue is the one you need to shade with your B2 pencil. Strike it a few times and measure how the resistance changed, you can check resistance by holding the red wire of your multimeter to the red point and the black wire of your multimeter to the pink point.

 

The stock resistance measures around 536 Ohm. For the solder mod we used a 20kOhm adjustable resistor and soldered it between the red and pink point. Doing this changed the voltage from 1.91V stock to 1.95V. To increase voltage we must lower the resistance of the variable resistor, before you power on your system always make sure that your VR is set to highest value.

 

Here is how we modded our card:

 

 

 

For the MEM mod we actually didn't use a 20k VR, we made the combination of putting a 10kOhm VR in series with a 10kOhm normal resistor. This will avoid over voltage (max 2V) and more currency on our voltage range.

 

For both GPU and MEM voltage modifications we used the same 'ground' connection. If you watch on our mod-pictures we see that we always have to solder between red and pink points. In real life those red points are points connected to ground. You can use any ground point for doing those modifications, though we always made sure we had a ground point available on each picture for people who want to use those points.

 

 

 

OCP Mod:

 

I Have successfully made the OCP mod for the 8800GTS (G80). What you do is solder 1.2K SMD resistors across the 3 caps i have outlined in pink. The stock resistance across the caps was 1.29k and with the 1.2k SMD resistors on it is reduced to 0.61k. This reduces the OCP signal by 51%. I also realised during testing that it also reduces vdroop from ~0.08v to 0.02v under load. I successfully ran bench after bench @ 1.52v idle, 1.50v load. You will need to improve cooling though, i have a modded heatsink & fan and it still hit 93*C during repeated runs of 3dmark05 GT2 but it was totally stable. I was able to bench stable at 702MHz gpu, the previous max was 684, and theres more left in it.

Source: http://www.xtremesystems.org/forums/showthread.php?171016-G80-8800GTS-OCP-VDROOP-MOD-Made-amp-Confirmed-Working

 

Edited December 29, 2013 by der8auer