Flashing bios from 650m to 750m - possible?

[Aikei]

So, Flashing bios from 650m to 750m - possible? Or impossible?

[svl7]

It might work, it works on some 650m, however I don't have a Lenovo system for testing so I can't guarantee anything. If I'm not mistaken I already explained it in another thread... the best option to test this would to flash only the ultra bay 650m with the 750m vbios, if it fails you can still use your laptop and most likely even flash back your ultra bay gpu with nvflash since it should still recognize the adapter.

Apparently so far no one really wanted to know whether it works or not, cause nobody seems to have tried it.

[octiceps]

As a 650M owner, I personally don't really care as I can easily overclock past 750M stock performance on the 650M's lower voltage. And my GPU runs cooler as well. If you want higher clocks there is a 1.1V overvolting BIOS for 650M made by someone else based off of svl7's mod. 750M runs at 1.125V by default but it's close enough.

[jester_socom]

I tried already.

I replaced three obvious instances in the vbios of the 650M to match the 750M but didn't work.

I want to log the error message by nvflash but I cannot find how.

nvflash -6 con750m2.rom > log.txt

that was the command I tried.

[RedLionRisen]

I tried already.

I replaced three obvious instances in the vbios of the 650M to match the 750M but didn't work.

I want to log the error message by nvflash but I cannot find how.

nvflash -6 con750m2.rom > log.txt

that was the command I tried.

[bcunje]

Hello techinferno. I apologize for the necropost, but I am working on fully converting a GN35 Ultrabay GT650M into a GT750M. I have already SUCCESSFULLY modified a GT755M Ultrabay into a GT750M as per this thread on notebookreview:

SLI'ing Y410P GT750M with GT755M Natively! No driver mods.

GT755M -> GT750M conversion was as simple as modifying the hardware straps, then reflashing. That's it. The current road of GT650M -> GT750M is proving to be a bit tougher.

So far I have successfully modified the hardware straps on the GN35, allowing the Ultrabay card to bypass the Lenovo Y410P white list. Now I am trying to figure out what vBIOS it needs. One thing to note is that the SPI flash chip on the GN35 is only 128k and not 256k like the GT750M/GT755M. Also the GN35 uses write protection whereas the GT750M/GT755M do not.

GN35: 128K Macronix MX25L1005

GT750/755: 256K Macronix MX25L200(5/6)

128K is still plenty to hold the 750M vBIOS however.

When the GN35 has the stock 650M vBIOS, it 'seemingly' works fine. It installs, shows up with the CORRECT 750M Device ID (10DE 0FE4) and even shows up as a 750M in Device Manager. Obviously the clocks and voltages are at 650M though. Oddly enough there isn't anything indicating that it's a 650M at all unless you use nvflash to read the vBIOS version info. Even GPU-z pulls up all 750M type info excluding clocks/BIOS version etc. With the stock 650M vBIOS it even tells you that the system is SLI Capable, but then black screens if you try to do so.

I was able to flash the 650M with 750M vBIOS, which reads fine in nvflash, but would never install correctly in Windows 8. GPU-z doesn't pull the right information after re-flashing as well... No matter if I clean installed Windows or reinstalled the nVIDIA drivers, it just doesn't stick. One thing to note is that the 650M vBIOS is definitely different than the 750M, and is about 6kB smaller in size. I've tried the svl7, original, 8.1 fixed, and modified versions of the 750M vBIOS and none work.

Just as a control variable, as soon as I slip in my modified [GT755M -> GT750M] Ultrabay, it works immediately.

Perhaps replacing the 128K MX25L1005 with a 256K MX25L2006 that doesn't have the write-protect bits and has the 750M vBIOS on it would work?

Any tips/suggestions would be greatly appreciated. I'm not too good with BIOS modifications, but can do any hardware mod in a jiffy. I've got all the equipment for that.

EDIT: I made a guide to downconvert the GT755M5 -> GT750M Ultrabay because Lenovo never released the GT750M4 for all the Y410P owners. The GT750M5 also cost over $250 whereas the GT755M was only $99. Now the GT755M isn't being produced anymore, but the GN35 is still available for purchase (even comes with 14" bezel). This is why I am trying to upconvert the GN35 -> GT750M.

EDIT2: Also something silly, when the GN35 is still on 650M vBIOS, GPU-z shows it as having Hynix GDDR5, when it is actually Samsung

[bcunje]

Apparently so far no one really wanted to know whether it works or not, cause nobody seems to have tried it.

@svl7 I was wondering if you could possibly take a look at the differences between the 650m and 750m vBIOS. I tried sifting through the two, but wasn't able to get my modified GT650M Ultrabay to work with a different vBIOS...