Help with bricked ASUS G531GW after undervolt in modded BIOS

Hi everyone! as the title says, I’m currently stuck in a black screen after undervolting too much the CPU.

I do have the stock ASUS bios (.307), the stock bios dump (pre-modd) and the modded bios file (by genius 239).

I steel haven’t done a bios dump with CH341A programmer since it will be arriving next wednesday. The BIOS chip is a MXIC MX 25L12873F M2I-10G.

Please help @Lost_N_BIOS ! Is it necessary any other information? I’ve read “[GUIDE] Flash BIOS with CH341A programmer” and seems pretty straightforward but if I understood correctly I need a programmable bios file made out of the stock ASUS bios and the stock bios dump, is that correct?

Thanks in advance!

PD: I had to upload the files splitted

* stock ASUS bios (.307) = G531GW-AS.307.part1.rar & G531GW-AS.307.part2.rar
* stock bios dump (pre-modd) = original 307 dump for genius 239.part1.rar & original 307 dump for genius 239.part2.rar
* modded bios file (by genius 239) = modded by genius239.307.part1.rar & modded by genius239.307.part2.rar
* MXIC MX 25L12873F M2I-10G photo = 20201001_212046.jpg

@klz_nqn |p125276

This looks like a laptop. Curious why are trying to undervolt this? Trying to reduce some heat?

Unfortunately even on desktops it can corrupt the BIOS slightly. This killed off the iGPU from being detected as a result. Sounds like something similar has happened. If you have the original BIOS before you did any tweaking and can reprogram this back exactly then it should work as normal. This is tougher to do on laptops which is why I don’t mess with them unless they are 5-10 years old where you break it you already got a lot of usage out of it. But I would not attempt these undervoltage hacks on a laptop. Their BIOSes are too limited and no way to clear it like on a desktop.

If you must modify the BIOS in some way I’d see if you can set the CPU Core Speed down to 800 MHz and it will run much cooler than trying to mess with the CPU Core Voltage tweaking and not require a new CPU swap.

You are better off verifying what socket CPU type your laptop uses. Then looking up all compatible CPUs for that socket and going for the most watt efficient model with the same or higher performance and higher cache. I’d done this for a few laptops swapping it with a newer CPU model with lower wattage than the original CPU. The end result was better performance and less fan noise since it ran cooler. Also maxing out the RAM slots helps and swapping the internal HDD to SSD if not already using one. If you’re already opening up the laptop internally vacuum out all the dust from the fan exhaust and apply some new thermal paste for the GPU and CPU.

Yes I do have both (probed to work ok) dumps pre and post modd (12MB in size). I do believe this issue can be instantly fixed by flashing the bios chip with a programming board as the problem is that there isn’t enough voltage to turn on the cpu due to a bad bios setting. I just need to confirm that the dumps i have can be used as is due to the 12MB size or if it’s necessary to add data to the dumps.

Also I should point out that these dumps where taken beforehand with the laptop working ok.


I’m not an expert with laptop BIOS flashing like LostNBIOS.

I just ordered one of those SOIC8 with clips recently and it will take a few months to arrive with the coronavirus shipping delay on top of that. :wink:

If this laptop is cheap enough to buy used on eBay I’d just get the same model or compatible one and swap the internal drive and call it a day if there’s important information on there and you just want to get it going ASAP.

But it sounds like you might need to desolder the BIOS chip from the laptop motherboard. I suck at desoldering so I wouldn’t even do this myself. Then you have to resolder it back which I assume is just as hard to do. If you could add a BIOS socket instead then you could save yourself another future headache if you plan on constantly undervolt tweak testing it. Then you can remove the BIOS chip and program it outside of the laptop motherboard when you brick it again.

Wait for LostNBIOS or someone else with Laptop BIOS experience to respond. He’s better with flashing laptop BIOS tips so he’s probably swamped right now.

That’s ok, I can do smd de-solder and solder. I’ve got the tools, done some diy smd projects too. I’ll give it a shot with the programmer clamp first though, if that does not work will scale to solder

@klz_nqn - For MX25L12873F use CH341A v1.31(1.4) (CH341AFree) (This is the name of the folder), ASProgrammer 1.4 or 1.41, or CH341A v1.1.1.32 -
But, I assume you already used one of those, or something else compatible, since you dumped chip and reprogrammed it with unlocked BIOS already. Ohh, wait! How did you dump BIOS to send to Genius239? I guess software
Sorry, I did not look at any attached files yet, it’s a mess to download split files from here, so unless/until needed I don’t download.

If EC FW did not change, or corrupt when you dropped the voltage too low, then you should just be able to program back either your original BIOS dump or the unlocked one you programmer in and then be back at square one.

Since you have not dumped BIOS with flash programmer yet, use above info I gave, and here is guide on how to use
[GUIDE] Flash BIOS with CH341A programmer

Dump current chip contents and upload here. Then someone, or myself, will help you to merge your dump with either your original BIOS region dump or unlocked BIOS region
ME FW may need cleaned as well (if not included in any of the original dumps), if it is included in the original dump package, then a direct swap in to fixed BIOS can be done to be sure ME FW is OK

For me to fix, once you dump chip with CH341A, please make a single zip package with original BIOS dump you sent to Genisu239 (complete package of the files created, if you used backup tool set from him), mod BIOS he sent back, and your dumped chip contents (only all this, do not need stock BIOS)
Then upload to any free file host and send me link

Soldering not required here

Great! I’ll posting soon when I get the programming board.


Ok then, the programming board arrived earlier. This is the link for the files requested. The dumps were verified successfully.

Thanks in advance!

@Lost_N_BIOS just to be sure, are the uploaded files ok?

I’m happy to inform that I’ve successfully recovered the bios, the laptop is working at a 100% now! :grin:

@klz_nqn - Sorry I missed helping you out with this, always buried and can’t keep up anymore
Glad to see you were able to recover things yourself!! All is working OK now? If yes, great, and good work


Ok then, the programming board arrived earlier. This is the link for the files requested. The dumps were verified successfully.

Thanks in advance!

So can you explain the steps you did to resurrect your laptop? At one point you mentioned because it was bricked it was not getting enough voltage to flash it back?

Since your laptop after looking it up is actually rather modern and also wondering if LostNBIOS could modify that BIOS to add CPU Ratio parameters so he can underclock to 800 MHz or even lower to 400 MHz on the laptop.

And can it be modified so he can adjust CPU Core Voltage?

Hi! to clarify, the laptop was working ok, even with the modded bios from genius239. I lowered the CPU voltage (via negative offset) too much and after that the laptop refused to turn on.

I read a lot of posts in many forums to gather information on bios modding and module replacement. In the end what I did was replace the bios module of the dump I made with the modded bios file genius239 sent me on the first time and flashed it to the chip. It worked rigthaway.

As for the software used:

* Hex Comparison: This one helped me see the "damaged" strings between the genius239mod vs the dumped bios.

* UEFITool_v0.28: This one is the one I used to perform the bios module swap. I also used it to check wich Intel ME version the dumped bios had.

* ME_Analyzer_v1.160.0_r212: This was used to verify (sort of) that the Intel ME firmware within the dumped BIOS was OK.

* CH341A v1.31(1.4) (CH341AFree): Used to dump the bios firmware, erase the chip, verify and program the bios chip.

Thats pretty much it, I can upload screenshots and photos if needed. I learned a lot of things in these five days.

This was a wild ride thougth.