I need some help: Volt modding my 9800 Pro's core.

I know *how* to do the volt mod, but am having some trouble applying it.

I have followed the volt mod instructions as shown HERE

I have soldered the connections securely, and have fired up the machine without the card dying - I get an image on the screen, and everything looks dandy.

Here's where the trouble starts. Using my multimeter to read the card's core voltage from the read point, I get a reading of 1.7V before the mod is installed, and 1.75V - 1.77V after the mod is installed. The problem?

Turning the trimmer has almost no effect on the voltage readout. If I turn the trimmer far enough to get a 1.77V reading from my multimeter, I get horrific artifacting in 3DMArk 01, as well as vertical and horizontal patchwork lines in 2D windows. Obviously the mod is working, but it's going to be a hard trip if I can't tell how much voltage I'm feeding the card!

Raising the trimmer's resistance to a full 10K Ohms still gives me a 1.75V reading. I removed and measured the trimmers resistance at the point where it gave me a 1.77V reading, and the resistance read as 5K Ohms - a dangerously low resistance that would be overvolting the core by a good deal.

I have removed the voltage modification at this point. I removed and reinstalled it *four times* to make sure my connections were good, and my nerves are totally shot at this point. All the installations started to show artifacting as I lowered the resistance of the trimmer.

Below is a picture of one of the mod installations.

Pic isn't too clear so it's hard to say whats going on. My suggestion would be to run the wire from pin 18 - to vr - to ground.

Maybe like this.


Only one wire needed. Clockwise rotation increase vgpu. And I am not too sure of that location shown in the guide you posted as a true ground.

Aha - thanks for the picture - it looks like there are two options for the hot point, and several for ground - I think you're right, that perhaps the solder point shown in the guide I used isn't a proper ground.

I'll try it again as shown above; thanks!

I probed it out a little bit, and found several useable grouning points in the area near the IC that controls the core voltage. I tryed a couple times to get a good connection to the pin shown in your picture above, but couldn't get it to stick, even with heavy tinning, and lotsa flux. I was going to ground via a motherboard fan plug, but I got it on my final try

Thanks again for the help El<(')>Maxi - it's working great right now, and looping the nature test perfectly

The lowest voltage I can get right now is 1.739V, from ~1.7 stock. Lowering the VR's resistance raises the voltage nicely, although it is really slow at first, and starts going up faster as the VR wiper goes farther.

Here's a nice pic - I splurged and added a molex to make it easier to read and adjust the core voltage at the same time without holding the multimeter in one hand, and the screwdriver in the other

Hopefully I'll have time to get the peltier on soon, and make proper use of this

Thanks a lot El<(')>Maxi !!

Great to hear you have success now

So you are pelt cooling?

Yes

Right now I'm looking for time to get the peltier/waterblock onto the card, and get the card's personal water circuit set up. I'm going to be using a 172W peltier on 12V for starters, and then up it to 20-24V when my 24V PSU makes its way up here. I'll be using a Maze 4-1, a Iwaki 6Z pump, and a Chevette heatercore for the peltier water cooling.

Right now I've got the stock cooler on the card, with RAMsinks. The RAM volt mod is next...

If you just wanna do a quick test, just touch it to your case.

I dont get it felin....your second pic looks like you soldered it in the same place as the first. What did you change?

If you look closely, I changed the grounding point, and also changed the hot point .

In my first attempt, I used the 'patch' hot point which is used in most of the modding guides. I changed it to the hot pin coming off of the IC which controls the core voltage in the second, successful, attempt. I also changed the grounging point to a different pin, as the first pin seemed to not be grounding properly.

The card is pelted up now, with a 172W Drift pelt @ 12V (it's a 24V pelt), and a Maze 4-1, idling at 8 degrees celcius with the core voltage at 1.75. I'm going to try the RAM volt mod as soon as my 10K Ohm Cermet Vrs get here.

Ahh, so you just moved the grouns 1 above the read point? Cool

is vmodding the Vcore and Vram the same for the 9800 as it is for the 9800 pro. I've read several times that the boards are identical but I just wanted to make sure before a buddy and I put his card to the test.


Nevermind, it is, found an OCFaq Post here: link