Mister Crowley

Before you read this I'm assuming you know a thing or two about electricity, and that you understand the risks involved in volt vodding a card.

This mod does NOT work on x800pro cards.
If your card is printed in the same basic way, it will work.

I noticed this site seems to have no FAQs on volt modding x8** cards, and I think I can make this topic much easier to understand for people who have the cards and want to get a little more voltage, as the only other guide I have read on vmodding x8** cards was somewhat vague. I have become somewhat of an expert on how to get it done easily with an x8**, and I think I can make it easier to understand than the guide I used.



*** Materials ***
You will need a digital multimeter. Dont try using a needle meter. radioshack has them for $30

For the vgpu mod you will need:
soldering iron (i recommend 15W tip)
solder
a pencil

For the vmemory mod you will need:
80 wire ide cable to be cut and used
Two 50kohm trimmers (potentiometers)
Hot glue gun
a conductive pen, $4 at radioshack
super glue

I dont reccommend you attempt to mod your card unless you feel perfectly comfortable with a soldering iron and you are committed to making changes to your card's circuitry. The memory vmod can be done without solder and this will be the method I show you.





*********************
***** GPU Volt Mod *****
*********************

For the gpu vmod there is no way of pencil modding only, though you must do one pencil mod.

This may seem like a drawback, but they have made the gpu hard mod much more reliable in a way than a hard mod on lets say, a 9800.

You want to start by finding the gpu voltage test point and making sure you get a reading of 1.4V or what ever your card's default is. To do this, plug the negative lead of the multimeter into a negative lead on one of your molex connectors. (the two black wires in the middle)

Then touch the positive lead to here:


Once you have found your voltage test point, take the card back out of your machine and get ready to mod!

The first step is to disable the card's automatic shutdown feature. This is done with one easy pencil mod. This feature shuts your machine down if the cards gpu voltage goes above default. We dont want this.

Set your multimeter to Impedence test or Ohms test. Test the impedence across this resistor. Resistor 1596.



It should show about 40kohms(more or less). Draw across the resistor with one hard stroke of your pencil and test across the resistor again. The impedance should have dropped some. Repeat drawing strokes across the resistor until it comes down to around 20kohms. The shutdown feature is disabled.



Next comes setting the actual gpu core voltage. This is done by a pattern of 5 resistors that make a binary code that represents your core voltage. In this guide, a resistor present will represent a 1 and no resistor present will represent a 0. This card has a default vgpu of 1.4 volts, so in the image above you can see resistors 1,4,and 5 are closed (1) and resistors 2 and 3 are open (0) this would read 10011 and in the table below you can see this represents 1.4 volts. To achieve 1.6V gpu core you would only need to close resistor 3 by soldering across the solder pads, which would read 10111 and result in 1.6 vgpu. If you wish to change a 1 to a 0 that has a resistor to close the circuit, break the resistor off with needle-nose pliers and should you ever want to close it back again just solder across the resistor pads.

Resistor / Vgpu
12345 / Volts

00000 0.000 || 10000 0.000
00001 0.925 || 10001 1.300
00010 0.950 || 10010 1.350
00011 0.975 || 10011 1.400
00100 1.000 || 10100 1.450
00101 1.025 || 10101 1.500
00110 1.050 || 10110 1.550
00111 1.075 || 10111 1.600
01000 1.100 || 11000 1.650
01001 1.125 || 11001 1.700
01010 1.150 || 11010 1.750
01011 1.175 || 11011 1.800
01100 1.200 || 11100 1.850
01101 1.225 || 11101 1.900
01110 1.250 || 11110 1.950
01111 1.275 || 11111 2.000


Looking at these two images you should see that the configurations are 1.6v and 1.9v respectively.


The highest voltage I would recommend on:

AIR: 1.550-1.600
WATER: 1.600 for low end w/c 1.650-1.700 for high end w/c
PELT 180W+: 1.800-1.900






*********************
***** MEM Volt Mod *****
*********************

This mod requireds a bit of ingenuity and a good amount of free time. Though it is tedious, you will have a custom creation when you are finished.



For the memory mod you will sacrafice an 80 conductor IDE cable. You must now plot out in your head how you will run the wires to the required locations.
I reccommend spending a good amount of time plotting how the wires will run, , stripping the ends of the wire next, and then hot gluing the wires in place. I reccommend also soldering wires to the memory test points to avoid shorting things out when trying to test memory voltage.

To get a connection to the specified leads of the two regulator chips, I super-glued the insulation of the wire on the edge of the top of the two chips, then used conductive pen (consistency like white-out) to make the connection between the copper wire leads on top of the chips and the leads on the chips themselves.

On this x850xtpe I had good results with the memory at 2.35V with good memory sinks

This is what mine looks like. There is an extra trimmer on mine. It ended up being for a pointless circuit.

Attached Thumbnails

         

sandiegoskyline

Well thought out, and well written. Makes volt modding all the more feasible for someone new to vmods.

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Malaziel

Good guide. I have been looking for a x850xt vmod guide for a while. How high can you go on the memory voltage without memory heatsinks?

__________________
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Mister Crowley

I wouldn't increase the memory voltage without ramsinks. Thanks!

__________________
Just Need.... One.... More... Upgrade.....
Agp x850xtpe @ 690/642 7784 3dmark05
Core 2 Duo E6600 Overclocks on Stock Hsf
x1900xtx running at 774/801mhz on pelt

Xeoc

Question... I thought you could do the memory mod with just a pencil? Or maybe I missed something?

Mister Crowley

You can do the memory with a pencil, but when the machine is running and you want to crank a little more volts on the memory and scan for artifacts, a trimmer is much easier to use for making live-adjustments. You must also get both memory voltages as close to each other as possible. This is also much easier to achieve by turning trimmers, when you add too much pencil, you have to rub it off and start over.

The gpu cannot be pencil modded

__________________
Just Need.... One.... More... Upgrade.....
Agp x850xtpe @ 690/642 7784 3dmark05
Core 2 Duo E6600 Overclocks on Stock Hsf
x1900xtx running at 774/801mhz on pelt