Mobile pascal TDP tweaker : how to avoid error 43 [GUIDE]

[JadeRover]

Hello,

 

This guide will explain how you have to actually modify a pascal/turing vbios with pascal mobile tdp tweaker in order to not get error 43 and black screen.

 

latest vesion 1.21 : https://github.com/LaneLyng/MobilePascalTDPTweaker/releases/download/1.2.1.0/Mobile.Pascal.TDP.Tweaker.1.21.zip

 

tools needed : any hex editor -> HxD for example

 

I have embarked on a long vbios modding adventure.

End goal : custom display tables in vbioses utility -> Extremely useful for MXM gpus -> looks quite possible thanks to released nvidia documentation but I must invest lots of time in research into this (my time allocation will vary greatly week to week...).

Side goal : create a core + memory overclocking utility -> Possible as well, simpler than the display table

 

Anyways, early on I noticed a flaw in the pascal bios tdp tweaker in the way it calculates checksums : it only corrects the checksum to the correct value if your vbios has no header ! If you use a vbios with header the app will calculate a wrong checksum and you will get error 43 or black screen as the security chip on the GPU will refuse to post.

 

Step 1 : Check if your vbios has a header -> Open it in a Hex Editor and see if the starting string is "NVGI" -> if no header, you can mod the base directly in TDP tweaker with no extra steps.

 

example of a vbios with a header :

 

Step 2 : Remove the header and keep it in another file, select all the first lines of the vbios untill you see the string "UxxxK7400". In my case the actual vbios data starts at offset A00 -> Save the modified vbios as "vbios_mod_applicable"

 

 

Step 3: Open this "vbios_mod_applicable" in mobile TDP tweaker, apply your edits and save the bios, now the checksum is correctly calculated automatically when you save this modified version.

 

Step 4: Open the TDP moded vbios in a Hex Editor and reinsert the header at the very beginning of the vbios. Make sure the file size matches between the OG vbios and the TDP modded one.

 

Step 5: Flash the modded vbios with an external programmer -> nvlashK and OMGflash will not work. You need to have a flasher handy anyway if you are attempting a vbios flash that risks bricking your card.

 

Step 6: Enjoy higher TDP/other changes you applied