# Why is the vbios size different when dumped from gpuz than when at command line



## gridrunner (Mar 25, 2017)

Hi. I need to dump some GPU Vbios. I normally do it from command line in Linux using for example

echo 1 > /sys/devices/pci0000:00/0000:00:02.0/rom
cat /sys/devices/pci0000:00/0000:00:02.0/rom > vbios.dump
echo 0 > /sys/devices/pci0000:00/0000:00:02.0/rom
I use these files for gpu passthrough in KVM.
I was hoping that gpuz would do this easier for me. However, the GPU vbios dumps are a different size.
For example, my 750ti from Linux dump is 131kb  but from gpuz its 165kb.

Why is it different. Unfortunately, the gpuz dump doesn't work for the purpose of GPU passthrough in KVM.


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## DRDNA (Mar 25, 2017)

This would be best suited for @W1zzard


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## W1zzard (Mar 25, 2017)

should just be some null bytes.

On recent NVIDIA cards, possibly including yours, the BIOS saved through GPU-Z includes some kind of NVIDIA header, which is required to be able to flash the BIOS using NVIDIA tools.

You might want to remove it for what you do. Remove everything before 0x55 0xAA


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## gridrunner (Mar 25, 2017)

W1zzard said:


> should just be some null bytes.
> 
> On recent NVIDIA cards, possibly including yours, the BIOS saved through GPU-Z includes some kind of NVIDIA header, which is required to be able to flash the BIOS using NVIDIA tools.
> 
> You might want to remove it for what you do. Remove everything before 0x55 0xAA


@W1zzard thanks. Yes, that makes sense. It would be very useful to be able to do. I use unRAID Linux and to be able to do this would be great for us guys. In KVM to dump the vbios is awkward. You can only do it when GPU is a secondary card.(due to vbios shadowing) If we could edit the files uploaded to techpowerup to work by removing the Nvidia header that would be awesome! Now my only problem is I am new to any kind od vbios editing. Which tool would I use to be able to remove everything before 0x55 0xAA
Thanks so much for the help


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## dorsetknob (Mar 25, 2017)

gridrunner said:


> If we could edit the files uploaded to techpowerup to work by removing the Nvidia header that would be awesome!


while that might suit you the vast majority of users would then have problems using the Nvidia flashing tool  kind of unfair to others
Suggest that if you need headers removed from vbios" you do it on an as needed basis"after you download them


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## gridrunner (Mar 25, 2017)

dorsetknob said:


> while that might suit you the vast majority of users would then have problems using the Nvidia flashing tool  kind of unfair to others
> Suggest that if you need headers removed from vbios" you do it on an as needed basis"after you download them


@dorsetknob No, I don't mean the vbios should be uploaded without the headers on the site. (that would be very unfair and selfish)  I mean it would be great if 'we' (me and others who need them this way) could remove the headers ourselves from the ones uploaded. I just don't know what tool to use to remove everything before 0x55 0xAA as @W1zzard suggests and was hoping with some help on how I do that.


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## dorsetknob (Mar 25, 2017)

I presume @W1zzard meant using a hex editor when he suggested 


W1zzard said:


> Remove everything before 0x55 0xAA


Suggest you PM @W1zzard to Clarify matters


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## gridrunner (Mar 25, 2017)

dorsetknob said:


> I presume @W1zzard meant using a hex editor when he suggested
> 
> Suggest you PM @W1zzard to Clarify matters


thanks yes, I have used hex editor and now can get the bioses working


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## W1zzard (Mar 25, 2017)

hex editor will work fine. maybe someone can post a sed oneliner


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