Using Variable Resistors

Understanding the same warnings as posted previously in the begining of the article. You should read the "Introduction" and "Starting Prep Work" sections.

There are many different ways you can do the Variable Resistor (VR) vmods. Each one is a personal preference on how you want you card to look and how much time you wish to invest in the vmod. From the color of the VR to where, how to place it and if to use wires or even adding a switch to turn off the vmod. Of course I have to mention that you need good soldering skills to perform the vmods using a VR. So take a moment to view some of our members VR vmods to get ideas and to post your pics at techPowerUp! here. Great work guys and thanks for taking the time to post the pics.

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Overview- click on pic to enlarge
The above pic gives us our vmod locations and points of reference. The blue Sapphire PCB #A474
has the same layout as the red ATI PCB, so it will work on all those models no matter which manufacturer.To the bottom right our arrow color code for the chips and measurement points, with the yellow arrow for our IGPU vmod.

Tools and Supplies

To do these mods you should aready have soldering skills and should be using a low wattage iron.

1. Digital Multimeter (have to have one)
2. Magnifying glass
3. Glue Gun (to set VR in place)
4. Variable Resistors: 1x 10k Ohm, 1x 250k Ohm, 2x 20k Ohm
   

Take note of the Max. Safe Voltages for different cooling in the "Introduction" section.

Next, read the "Starting Prep Work" 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 & IGPU

VR VGPU & IGPU

Locate the two solder pads in the above pic, where you will use the 10k VR for the VCore vmod. Set the VR to 10k or as close to 10k as it will go using your mulitimeter. Check the resistance 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 15k Ohms Verify the voltage and test your card for artifacts and lockups. Review the max. voltages suggested for cooling needs.

Locate resistor R1596 in the above pic 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 resistance around 20k Ohms. Remember this vmod does not increase your overclock, but increases the max. you can set the VGPU voltage before the card will shut off.

VR VDD & VDDQ Vmods

VR VDD

Using the above image we will solder a 20k VR to the pins 5 & 7 of the VDD chip ISL6522CB.
Set the resistor to 20k or as high as it will go and check the resistance before, then after you solder the VR. Verify the voltage and test your card for artifacts and lockups. Generally speaking, it helps to do the VDDQ along with the VDD vmod, in other words if you do the VDD you should plan to do the VDDQ as well. Review the max. voltages suggested for cooling needs.


VR VDDQ

Same as the last vmod, use the above pic and solder a 20k VR to the pins 5 & 7 of the VDDQ chip ISL6522CB. Set the resistor to 20k or as high as it will go and check the resistance before, then after you solder the VR. Verify the voltage and test your card for artifacts and lockups. Review the max. voltages suggested for cooling needs.