Mod your Radeon 9800XT voltage with a humble pencil.
This is a simple guide to some simple pencil mods for your Radeon 9800 XT.
All you need for this job is a pencil (2B prefered), an eraser, a multimeter
and some guts.
First you should measure your stock core voltage. Measure it from this small
contact spot with the red tip of your multimeter.
Red tip to spot and black tip to grounded spot like your video card handle.
You’d have to measure it while the PC is running so be careful. It usually
measures around 1.77v. For this card, it measures 1.77v.
Next, turn off the PC and take out your card. Focus your attention toward area
marked with green circle.
Look for the resistor marked R1597.
Measure the resistance across the resistor with your multimeter.
It should read around 342 ohms. Mark down the default resistance. Now you can
start to pencil it.
Pencil it in such a way.
After each smooth stroke, measure the resistance across the resistor. Add 1
stroke on top of another to lower the resistance more and more. I would go in
15 ohms steps. Dropping the resistance from 342 ohms to 327 ohms, my core voltage
increases from 1.77v to 1.81v. So, roughly, a 15 ohms drop will increase voltage
by 0.04v. Thus, I would reduce resistance by 15 ohms, then run the card to see
the increase in voltage, repeatedly until I reach the voltage I’m satisfied
with. Do remember to check the resistance before running the card to ensure
you don’t drop the resistance too much. When done, paste a tape over the mod
spot so that the graphite doesn’t get blown off.
With very good aircooling, 1.9v should be fine. With better cooling, 2v or
above is feasible. When you go above 2v and run it overclocked high, you may
trigger the over-current protection when your card draws too much power and
our PC goes into blank screen mode. You will need to do the over-current protection
mod, which can be done with a pencil as well.
Look for R1596.
Measure it with your meter. It should read around 40K ohms. Just pencil it
to around 20K ohms the same way. This should solve the over-current problem.
When done, paste a tape over the mod spot so that the graphite doesn’t get blown
So that’s it. For Voltage mods basics and guide, you can refer to