Radeon X800 Pro/XT/XT PE Voltmods

Author: Urlyin
Date: 2004-09-30 17:16:51

Using Variable Resistors

This section I decided will be brief due to time restraints and less descriptive. Understanding the same warnings as posted previously in the begining of the article. You should read the "Introduction" and "Before you Begin" sections.

There are several VR How-Tos on the web. Each one has a different tweak, it's one of those more than one way to skin a cat deals. But we'll just do the basic VR to resistor solder.


Image 4


Image 5


Image 6

Tools and Supplies

To do these mods you should aready have soldering skills and should be using a low wattage iron. I also assumed that you would be using a magnifying glass and until now didn't think to mention it.

  1. Digital Multimeter (have to have one)
  2. Glue Gun (to set VR in place)
  3. Variable Resistors: 1x 10k Ohm, 1x 250k Ohm, 2x 20k Ohm
Take note at the top of the page for the Max Safe Voltages for different cooling.

Next read the "Getting Started" section to get your default voltage. This can be important to get an idea of where your voltage will be when you crank up the card. You can still use the same table as the pencil mod. What I mean by that is if the default Ohm reading of the VGPU is at 420 and you add the 10k VR, then given that a 10k VR will give you around .04v which in turn equals 15 Ohms then after adding the VR your new Ohm reading should be around 405 Ohms.

VR VGPU

Locating the resistor R1597 in Image 5 you will use the 10k VR. Set the VR to 10k or as close to 10k as it will go using your mulitimeter. Check the resistance on R1597 to compare after you solder the VR. You can either solder the VR to the resistor directly or you can use wires. After soldering the VR on check the resistance. Remember a 10k VR should give you around 15 Ohms. Test your card and verify the voltage.

VR IGPU Over Current Protection Vmod

Locate resistor R1596 in Image 5 and set your VR to 250k. Check the resistance on the resistor to compare after you solder the VR on. Again after soldering the VR on check the resistance. Like with the pencil mod you want to drop the resistence around 20k Ohms.

VR VDD (VMem) Vmod

Using Image 6 we will solder a 20k VR to the pins 5 & 7 of the VDD chip. Set the resistor to 20k and check the resistance before then after. Test your card and verify the voltage.

VR VDDQ Vmod

Same as the VDD vmod but on a different ISL6522CB chip below the VDD locate the VDDQ in Image 6. Just like the VDD set the VR to 20k and check the resistance before then after. Test your card and verify the voltage.


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