T61 Nvidia GPU undervolting: success!

[Binh]

Recently I had finished a project on building a T61 15” Flexview Frankendpad.
The donor T61 is 8889-ACG and unfortunately it has dedicated NVS-140M GPU. Comparing to Intel X3100 integrated video it has some serious drawbacks:
- It is prone to Nvidia GPU bug with bumping material (see sticky topic for details).
- It consumes a lot of power: at idle my T61 FV consumes 14.3W with all off, backlight at lowest level, and Powermize is on max battery. While another T61 15.4” WXGA with X3100 GPU consumes only 9.5-10W. Take into account that my Flexview UXGA requires 1-1.5W more than the 15.4” WXGA, I estimated that the Nvidia GPU consumes about 4-5W at idle, while the Intel one consumes about 1-1.5W.

So my biggest concern is to lowering power consumption of Nvidia GPU. Using Nvidia Inspector and NVPMManagerUni, I set the GPU at fixed max battery level and underclock the GPU a bit, to 130Mhz. However, the power consumption was still high because the supply voltage for GPU was still 1.15v. Therefore, my next objective is to lowering the GPU voltage.

However, unlike CPU voltage, the mobile GPU voltage can not altered by software. Some PC video card can change voltage by altering the so called voltage table in its BIOS using NiBitor software, but this software does not recognize mobile video card where video BIOS is integrated with main BIOS. Therefore, the only way I can go with is to make hardware mod in the GPU power supply system.

I had found that Lenovo uses ADP3209 IC to control the voltage of GPU. This IC has 5 VID pins (like CPU power supply systems). Before going into action, I tried to overclock my GPU, and it could go as high as 650Mhz at 1.15V. So my estimation is that it can keep the default frequency of 400Mhz at about 0.90V. Based on that, I decided to give the VID3 voltage level of 1 instead of 0.

To do this mod, I removed the 0 Ω resistor R590 from the board to give high (1) signal level to pin 26 (VID3) of the ADP3209 IC. However, due to unknown at this moment reason, the voltage at this pin is still low (0). To cope with it, and due to the fact that before I accidentally remove R537, I connected pin 26 to pin 27 (VID2) and they both have high level. The GPU voltage after this mod is 0.95V for Powermize lowest performance level (before: 1.15V) and 0.90V for highest performance level (before 1.20V). You may find strange that the latter voltage is lower than the former

The laptop boots without problems, at 0.90V I even can overclock the GPU a bit, up to 450Mhz. Using Video Stability test, I had found that the GPU temperature droped by 8-10 degrees Celcius (from 74deg to 66 deg according to GPU-Z, or from 65 to 58 deg according to TPFan control). Another effect is that at idle, the laptop consumes only 13.0W instead of 14.3W before the mod. Thus, the battery life on my 9 cells 77Wh battery is extended by 10%, up to 4.5 hours comparing to 4 hours before. Hope that with lower working temperature, my Nvidia GPU will work longer

Here are images of ADP3209’s VID voltage table and this image (I don’t know this image will violate the forum rule or not. If yes, I will remove it). The actual picture of mod will be posted later.

[Amigaman]

That's a very brave hack, I'm impressed!

Also I didn't even realise that it was possible to find the T61 (or other Thinkpad) schematics.. They would've been useful for T43 fan speed hacking in the past!

Ross..

[Harryc]

Studying T61 schematics, on page 85 I had found that Lenovo uses ADP3209 IC to control the voltage of GPU.

Please do not be tempted to post a link to any Thinkpad schematics here, it is not allowed. Thank-you.

[Binh]

Please do not be tempted to post a link to any Thinkpad schematics here, it is not allowed. Thank-you.

Yes. Thanks for reminding. I know about this rule . I removed some sensitive words in the first post.

[piekon]

Hi everyone.
Binh, thank you for your effort here, you did really good job.

However, due to unknown at this moment reason, the voltage at this pin is still low (0).

Ok, there's no 1K R494 pull-up resistor on the motherboard (no_asm label).

To cope with it, and due to the fact that before I accidentally remove R537, I connected pin 26 to pin 27 (VID2) and they both have high level.

To make this more safe and clean do not connect pin 26 to pin 27 but instead simply mount R494 (1005 SMD package size).

[Binh]

Ok, there's no 1K R494 pull-up resistor on the motherboard (no_asm label).
To make this more safe and clean do not connect pin 26 to pin 27 but instead simply mount R494 (1005 SMD package size).

Thank you for your remark. I noticed the NO_ASM in the schematics but did not update the orginal post.
Concerning idea of mounting R494, it will be certainly better but for me it is easier to connect pin 26 to pin 27
So far, after one year of applying the mod, I still have no problem with GPU in my T61.

[piekon]

I made this mod two days later than my post. My motherboard originally was slightly redesigned. All GPU VID pullings are 3k instead 1K components. I'm not IBM tech but I think it's due to a timing reasons. Oirginal VID <4...0> was 00110 and after my mod 0111X instead of 011XX (I removed additional R429). This gives practically all the time only one level (0.900v), I also tried to force 0.875v but unfortunately it is to low.

CPU undervolt - I give up, T8100 and RightMark CPU causes immediately hangs and I haven't time to cope with this.

[Lockheed]

Is it possible to do the same think on R61 (15.4" + Quadro)? Are the same transistors are involved?
It is basically the same laptop.

I need to undervolt my Nvidia cause I don't think the motherboard will survive oven baking for the third time.

[RealBlackStuff]

If the baking fails, I have an absolutely stunning 15.4" T61 with nVidia from 08/09 (2008/September) which has the good GPU, as well as a T9300 CPU.
For the right price I'd be willing to sell that to you. PM me if interested.

[Lockheed]

If the baking fails, I have an absolutely stunning 15.4" T61 with nVidia from 08/09 (2008/September) which has the good GPU, as well as a T9300 CPU.
For the right price I'd be willing to sell that to you. PM me if interested.

I did it the second time 2 days ago. Last time it held up for over 7 months, so I count on another couple of months (or years if I do the NV mod) while making arrangements for t530, but thanks for the offer.

[jedisurfer1]

I'm very impressed but this mod might be too time consuming for me. Are there any other software mods or bios settings you did to get it 11 watts idle?

[Lockheed]

To do this mod, I removed the 0 Ω resistor R590 from the board to give high (1) signal level to pin 26 (VID3) of the ADP3209 IC. However, due to unknown at this moment reason, the voltage at this pin is still low (0). To cope with it, and due to the fact that before I accidentally remove R537, I connected pin 26 to pin 27 (VID2) and they both have high level.

I am somewhat confused by that paragraph:

1. Wouldn't removing the resistor break the pathway of electric impulse? Shouldn't it be replaced with some kind of non-resistant connector?

2. Instead of removing the resistor, would it work if I just pencil it over with a soft graphite pencil? I used to do it back when I was using desktop systems and it worked well. I am not really good with a soldering iron... nor have one readily available, for that matter.

3. This accidental removal of R537 - are we supposed to replicate it and remove it, too, after which we apply the fix proposed in this description? Or should we just leave it be AND apply the fix? Or should we just ignore that part, as we never actually removed R537 in the first place?

[xirtyllo]

here I am resuscitating an old post! but given that a T61 never gets old... : -)

I really would like to attempt this mod, I think that reducing the Nvidia temperatures of 8-10 degrees makes total sense! (that's the only reason why I miss the X3100... it was so much cooler & quieter!)
I already have an undervolted T8300 cpu (the coolest cpu apart from T8100), so the Nvidia is constantly the hottest part, even at idle.

from Binh's post I understand that I need to remove R590 and R537 resistors (are they resistors?) and connect pin 26 and 27...

sounds fairly doable, even for someone without experience like me... my problem is: how can I individuate where these resistors and pins are located on the motherboard..??? I'm totally lost there.. maybe I need the schematics in order to individuate those?

help much appreciated, even in PM if necessary : -)

[leromarinvit]

1. Wouldn't removing the resistor break the pathway of electric impulse? Shouldn't it be replaced with some kind of non-resistant connector?

Yes, it breaks the connetion. That's the entire point. So no, don't replace it with anything else. In fact, the resistor is a non-resistant connector, since it's a 0 Ohm resistor. It's just a point in the circuit that's meant to be relatively easy to open or close for testing purposes.

how can I individuate where these resistors and pins are located on the motherboard..??? I'm totally lost there.. maybe I need the schematics in order to individuate those?

Look at the datasheet for the ADP3209 IC for the pinout (the relevant pins are VID0-4), and then look at the PCB. Of course, schematics do help to get an idea what you're looking for. Apparently it's not allowed to post a link here, but the T61 schematics are easy enough to find.

There are 0 ohm resistors between whatever drives the VID lines and the ADP3209. There are pads for both pull-ups and pull-downs for VID0-3 (VID4 is grounded). Only one of these is populated for each line though. I removed the series resistors for VID0 (R579), VID1 (R429) and VID3 (R590), and changed the pull-downs of VID0 and VID3 to be pull-ups instead (R587 -> R602 and R520 -> R494). The result is that the VID only switches between 01011 and 01111, resulting in 0.975V for the max performance setting and 0.875V for min perf. Going any lower than 0.875V would be a bit more complicated, since VID4 would need to be changed from low to high (and I have no idea if it would actually still run at 0.750V/0.800V, which would be the easiest to get without changing anything else).

At 0.975V, my NVS 140M is stable (runs FurMark for several hours) at 575 MHz GPU / 920 MHz VRAM, and at 0.875V it's stable up to 487 MHz GPU / 783 280 MHz VRAM. Temps while running FurMark are 80°C and 72°C respectively, with the fan pinned to level 1 in TPFC. In idle the fan does come on occasionally, but much less often than it used to (with standard TPFC trigger levels, e.g. 65°C).

On my 4:3 T61, the ADP3209 is on the bottom of the PCB, to the right of the WLAN Mini Card connector. The pull-up and pull-down-resistors are on the opposite side (i.e. top). Here are some photos of the finished mod: https://www.dropbox.com/sh/9eak721l42itf3y/46YemsLX77

Remember to use the pull-down resistors you removed for the pull-ups and not the ones from the opposite side, since they're 2.2K resistors instead of 0 ohms!

Update: While the GPU itself works fine at 0.875V (even overclocked), for the memory interface, this seems to be slightly less than what's needed for stock speeds. FurMark works fine, but overlay video causes problems. There are artifacts in VLC (funky moving green stripes even when stopped) and the Flash version of YouTube crashes regularly. So I actually have to downclock the VRAM interface to 280 MHz at 0.875V from the stock 300 MHz. Still good enough. At 0.975V, 920 MHz still works fine.

[xirtyllo]

this helps,

thank you!

[RMSMajestic]

This is awesome!!!!!
May I forward this to 51NB?

[xirtyllo]

since I never used a solder and I don't have one...

would it work if I simply break/remove the resistors (R590 and R537) with some small pliers..?
and if I use one of those "conductive ink" pens to connect pins 26 and 27?