Replacing Flash Chips - ISpillMyDrink/UEFI-Repair-Guide GitHub Wiki

When replacing 25 series flash chips on a motherboard, it's usually a good idea to use the exact same chip as was originally on the board though it is possible to replace with similar ones. When doing so, there are a few things that have to be taken into account:

  • The replacement chip will have to have the same pinout (duh).
  • The replacement chip will have to have the same or a compatible package type.
  • The replacement chip will have to work at the same supply voltage. That'll either be 1.8V or 3.3V. Do not under any circumstances use a chip that doesn't work with the same supply voltage.
  • The replacement chip will have to have at least the same size of storage. If your original chip is 8MB in size, it's fine to use a 16MB sized one (this may require some additional work on the firmware image though).
  • If the original chip supported Dual or Quad SPI, the replacement chip will also have to support those.
  • The replacement chip will have to support at least the same clock speed as the replacement. Higher clock speeds are fine.
  • The replacement chip will have to be part of the VSCC table on Intel systems.

When working on a system which stores firmware on more than one flash chip, where one of the chips is damaged, it might be prudent to replace both chips.

Chip Naming Conventions

TODO

Vendor Specific Component Capabilities (VSCC)

For Intel-based systems it's important to choose replacement flash that is contained in the Management Engine's Vendor Specific Component Capabilities (VSCC) table. If the replacement chip is not contained in this table the ME may not be able to communicate with the chip. To check this we can open the dumped UEFI image from our original flash with UEFITool and read the VSCC table from the Descriptor region.

It is not enough to only choose replacement flash based on this table, other specifications have to match aswell!

This table can in theory be edited with the Intel Flash Image Tool to add or change entries but that is very much not recommended for multiple reasons.