View Full Version : vgpu - climbing voltage?
adrift02
10-10-2008, 08:39 PM
This is happening with a 4850 when using a pencil mod. Here is what is happening. Let's say I get 1.2v after booting into windows (max 3d profile volts forced already). I start atitool (or any 3d stressor) which will boost the voltage a bit, lets say to 1.25v in this case. However, the weird part is, over the next 10 min my voltage will continue to climb in .001 increments. Usually settles after about a .005 - .01v climb. Also, once I quit the program (and as long as I don't force a voltage change through the profile), the previous idle voltage (1.2v in this case) will have kept the .005-.01v increase.
Not that big of a deal considering I can just base my OC/pencil mod off the peak climb, but what is causing this? I am making sure to blow off any extra graphite with an aerosol can...
adrift02
10-12-2008, 11:21 AM
Update: So I did some more testing and found that over the course of an hour my voltage will climb as much as 0.024. That is a huge increase over idle and doesn't seem right...
Right now I have got my pencil mod to idle at ~1.385v. Stressing in 3d jumps this to ~1.4v, and after an hour I am around 1.424v. Right now I am wondering if I had found a stable OC when my voltage was peaked at 1.424v, could it theoretically be unstable until I play for an hour and let the voltage climb high enough? Weird stuff....
arroyo
10-13-2008, 11:55 PM
It's normal. Those weird voltage changes results from temperature. Graphite from pencil, when gets heater change a bit his structure and conduct better. His resistance drops a bit. I've done pencil mod on my HD4850 and I've had the same issue as you. I started from R~1320ohm and after couple hours pencil modded resistor had only 1200 ohm. It boosts my voltage from 1,3V (1320ohm) to 1,34V (1200ohm) at load. After 3 weeks the pencil modded resistor had only ~1150ohm. I found that after 1,35V on GPU overclocking results were worst than at 1,3V (LOAD).
Make experiment: After pencil mod, use hair dryer to warm up area with modded resistor. check resistance before and after :)
Pencil mod is cool because it's cheap, fast and easy....but if you want to work with pencil-modded card for a long time....it's suck :down:
CryptiK
10-14-2008, 03:10 AM
This is a common phenomenon with pencil mods, and is a good reason why you need to use properly done hardmods.
adrift02
10-15-2008, 08:10 AM
IC, makes sense. Thanks for the info!