Voltmod and soldering basics

All modifications at your own risk! Make sure you know what you are doing. Be aware that you will lose the warranty of your hardware.

Equipment

The equipmen is very important for successful voltmodding. I use an ERSA RDS-80 soldering iron station with 80 W and a maximum temperature of 450°C. Don’t be afraid of the high temperature. The higher you go the faster you can solder and so you don’t heat up e.g. the whole capacitor.
However, sometimes it’s also better to solder at only 350°C because the flux will not disappear that quickly which makes it easier to solder as well.
The soldering tips are also very important. I use a 0.4 mm tip for the SMD soldering and a 5 mm tip for the thick wires.
     solder_1 solder_2

Equipment:

  • Soldering iron / soldering iron station (75 Watt or more!)
  • Various soldering tips
  • Copper strand
  • Soldering tin
  • Wire cutter
  • Wire stripper
  • Different adjustable resistors
  • Shrink tubing
  • Glue gun

Basics

First let’s take a look on how a voltage regulator module (VRM) works. The following picture is a 4 Phase VRM which should help you to understand how your modification works and where you find the measuring points.

phasedesign

On the left side you can see the PWM-Controller which is connected to 4 Driver ICs. Each driver is controlling two MOSFETs (high, and low side). The MOSFETs basically change the voltage from 12 Volt DC input to the required GPU voltage like 1.2 Volt. After each phase you have an Inductor and capacitors (C) which are eventually connected to the GPU or CPU.

On some cards or mainboards the Driver and MOSFETs are also in one package. So don’t be surprised if you can’t find every single piece on your hardware.

To measure the voltage you can always use the positive side of the capacitors. Here is an example of a GTX 780 Ti:

IMG_6015

IMG_6016

To change the voltage you can solder a variable resistor (VR) between the feedback (FB) pin of the PWM Controller and GND.

First steps

Before you start with expensive high-end cards you should do some practice on old cards or mainboards. I picked a dead 9800 GTX to show you the basic steps of soldering.

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1. Prepare the soldering iron
Pick the soldering tip as big as possible and as small as necessary. A small tip can store less energy than a bigger tip. So it can happen that the soldering iron just sticks to the part or you can’t even get the soldering tin to melt.
Make sure that the tip of your soldering iron always stays clean. I use a wet sponge to clean the tip each time before usage.

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2. Prepare the copper wire

Take a piece of wire (about 5-10 cm), remove the insulation at one end and apply soldering tin on it. Now cut the end of the wire to about 1 mm length which is still enough to use the wire but it is insulated as much as possible to prevent shorts.

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3. Prepare the soldering joint

If you apply some soldering tin on the soldering joint as well, it will be much easier to apply the wire there later.

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4. Final steps

Now take your copper wire and place it to the part where you want to apply it. A quick contact with the soldering iron will connect both parts.

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The voltmod

After you have gained some experience in soldering you can start with the real voltmod. We will mod a 8800 GT to change the GPU voltage by applying a FB-mod to the IC.
To get the correct resistance you have to measure from FB to GND and multiply the value by 20.
Example: 52,3 ohm measured -> x20 -> use a 1k VR

To mod the 8800 GT we will use a 500 ohm VR. Lower resistance means higher voltage.

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Prepare the soldering joint

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Connect the copper wire and fix it with the glue gun

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Apply the GND connection and prepare the VR

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Finish the modification and insulate with shrink tubing

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Let me know in the comments if you have any questions about modding or soldering :)

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