8MB bios in a 4Mbit chip ?

I’m planning to flash the bios.
The bios chip is a Winbond 25x40clnig which should a 4 Mbit chip, but the bios size is 8 Mbyte.
How is even possible ?

@darkon11 - Sounds like you are looking at the wrong chip, or you have the wrong BIOS? Some boards have two BIOS chips, and in these cases (and many others even with single BIOS chip) you cannot simply write BIOS you download to the BIOS Chip.

First, dump the BIOS contents, both chips if there are two, then check in BIOS tools and confirm they are actually BIOS or valid contents (not simply verified by programmer, which can still be blank - all FF or 00)
If you are unsure how to do that checking, zip and upload the contents I will check for you.

You need these dumps for several reasons, mainly so you can verify you have the correct working software version for your chips (not all versions work for all chips), and to try and get a backup of any board specific details you may need to put back in BIOS later (Serial, UUID, LAN MAC ID etc)

Please link to your BIOS download from the manufacturer and I will check it for you too.

Wow thanks.
Looked better and found a 64 Mbit chip.
I plan to flash the dump I made with a ch341a programmer in linux.
Do you suggest a specific software ?

I suggest you do what I mentioned first, and dump both chips, BIOS is often 12MB in this case and is not split evenly, so you can’t program one chip without programming the other. Sometimes you can, but I highly suggest you dump both, and get it confirmed that they are good dumps before you write anything.
Sorry, I don’t know anything about Linux, I use windows and here is the standard windows CH341A software all versions - http://s000.tinyupload.com/index.php?fil…257455007472602
Maybe you can use flashrom in Linux I think, but I have no clue what versions

Thanks, I’ll do the dump of both chips before flashing.

If you want properly working BIOS, with all your details in it, upload the dumps for me and link stock BIOS package and I will compile a proper update package for you to use with programmer to program back to both chips.
If you do not do that, you will loose board specific details such as serial, UUID, Asset Tag (if Dell), LAN MAC ID (Ethernet functionality), and possibly windows activations too. And it may brick board also, depending on where and how the BIOS is split between the two chips.

Yes, FlashROM supports the CH341A since version 1.0 (disclusure: I just sent a differential revision for review on the Solus Phabricator, updating the FlashROM package in the Solus archives from 1.0.1 to 1.1)