Help undervolting GT635M in ASUS S56 (K56 series)

Hello guys.
I have got this ASUS S56 laptop with i5-3317U and a GT635M with 2GB of memory. The laptop itself is nice, performance and battery life are good enough for my purposes. However, I found out I cannot play almost any PC game. Indeed, most of them utilizes at least 80% of GPU. This in a normal computer should be OK. In my case, this GPU usage converts into an abnormal heating (about 82°C at most). After 10 minutes of playing the computer becomes very hot to the touch, and I must shut it down.
After having read this thread and seeing the temperature improvements of that GT540M, I decided to come here and ask for help in undervolting this card.

I have tried to save my NVIDIA bios using programs like GPU-Z or Nvidia inspector, but both fail reading it. Using nvflash in a DOS environment resulted in the "Unknown EEPROM" error message.
I then decided to extract it from my laptop's original bios. Using Andy's Phoenix tool and a hex search tool I found out NVIDIA bios is contained inside these two modules:
- C5D7EAAD-B218-482C-A909-E3B8CDB00E94_564.ROM
- A062CF1F-8473-4AA3-8793-600BC4FFE9A8_579.ROM

However I don't know how to edit those files. So I am asking here for some help.
Thank you all in advance

 

This is a 6xx series GPU so I would say this laptop is at least 3-4 years old. What you need to do before messing with the vBios is to open it, clean the vents and fans and repaste.

This will yield much but results as there is no point in undervolting an old low end chip that has been running for a long time and will most probably won't undervolt that much in the first place.

 

I bought this computer as broken at a very cheap price and successfully repaired it by flashing a new BIOS. I know it's a bit old, but it's still better than my last laptop and I daily use it.
When I had to repair it I disassembled it and cleaned everything, as well as applied a new thermal paste.
Of course when I noticed the overheating issue I disassembled it again and changed thermal paste another time, but this didn't changed the situation.

 

How many heat pipes does the machine have and are they shared between GPU and CPU?

 

It has got two heatpipes. One is dedicated to the CPU, while the other one to the GPU.
Here is a picture of it.

 

We aren't gonna get much of that heatsink then. Have you tried to undervolt using Nvidia Inspector to test a stable undervolt for the modded bios?

 

Yes I tried but I could not set the new clocks and voltage. Every time I click the button the values reset themselves.
In any case, I could only drop the voltage from 0.937 to 0.837 for P-State P0.

 

I am personally not familiar with this GPU but 0.937V for P0-state is as low as I would let a GPU run. 0.837V is very low for an old piece of silicon. @Prema knowledge can be of more use on the topic.

 

While waiting for a response from Prema, may I ask you if you know some programs to edit this BIOS file?
I personally tried to use KeplerBiosTweaker which actually reads it but due to its GUI I cannot see the selected voltage value from the slider.

 

I think I solved it by myself afterall.

Firstly, I disassembled the laptop again and found out that the thermal paste was not covering the copper over the chipsets. After having replaced it, thermal conductivity has quite changed.
However, when playing, the CPU and GPU heated up to 80°C. Note that at 80°C the graphics card starts throttling. After having noticed that this laptop does not have a proper fan intake, I thought I could create one like many people online did with their cooling mods. Before doing something I could regret, I tried to remove the bottom cover and I tested the laptop. Temperature did not really change, maybe just 1-2°C less, but the GPU reaches 80°C anyway.

So I decided to undervolt it first using KeplerBiosTweaker and a hex editor. The undervolt had success but the temperature didn't change much. So I decided to do both an underclock and an undervolt.
After some tests, I found a good configuration.
By default, the GPU maximum clock state is set to
- 800 MHz core
- 900 MHz memory
When throttling, the GPU core clock goes to 660 MHz. Therefore, I have chosen this frequency as the maximum one, and hex edited the remaining entries to be proportioned.
Also, I have reduced memory frequency.

So now the maximum clock state is set to
- 660 MHz core
- 800 MHz memory

The voltage for all the entries is set to the minimum, 825 mV.

With this BIOS the laptop runs cooler and when playing it does not go beyond 70°C. In a Furmark test, GPU heats up to 74°C maximum (in a 3 minutes test), while with the original BIOS it got past 80°C (in under 30 seconds!).

I have attached the modified BIOS here, if anyone wants to look at it or use it.