Tried flashing the bios with my Xgecu T48 and a clamp.
Assuming the bios chip is the one circled in white on the above picture I was able to read it (a series of 00) and even to flash it but the process failed with the following message:

ERROR! FLASH Address:0x000000 Buf_Val:0x55 IC_Val:0x00

Any advice?

I read that my symptoms can be caused by errors in communications between the gpu chip and the bios or by AGP uncorrect voltage delivery.
To be honest I am in the dark and trying everything I can.

Now I put the poor thing in a Isopropyl bath, maybe this can further clean contacts?

Your ATIFLASH detected ROM as SST45LF010/C which is 1 Mbit, onboard is ST (M?)25P05 - stated as 512 Kbit.

That's the vBios chip on your board.
Sometimes flash programs will not detect them properly, especially if the chip is damaged in any way.
Had this happening to me very recently with an Nvidia card. Tried to flash it with external programmer but failed while chip was still attached to board. Once removed , tried the programmer again and this time the chip was recognised but alas it was defective.
You'll need a chip from a donor board or hunt for one if yours is damaged.
If you have a hot air station it's easy to remove it and test it.

Ydee wrote on 2026-07-12, 09:19:

Your ATIFLASH detected ROM as SST45LF010/C which is 1 Mbit, onboard is ST (M?)25P05 - stated as 512 Kbit.

That is why I think Atiflash is deceiving.

kiacadp wrote on 2026-07-12, 09:44:

That's the vBios chip on your board. Sometimes flash programs will not detect them properly, especially if the chip is damaged i […]
Show full quote

That's the vBios chip on your board.
Sometimes flash programs will not detect them properly, especially if the chip is damaged in any way.
Had this happening to me very recently with an Nvidia card. Tried to flash it with external programmer but failed while chip was still attached to board. Once removed , tried the programmer again and this time the chip was recognised but alas it was defective.
You'll need a chip from a donor board or hunt for one if yours is damaged.
If you have a hot air station it's easy to remove it and test it.

Desolder is out of discussion at the moment.

According to this https://68kmla.org/bb/threads/ati-radeon-9250 … ls.51352/page-2, the ST ROM is also 1 Mbit, but is limited to 512 Kbit due to defective cells. Maybe others have failed as well?

Ydee wrote on 2026-07-12, 10:35:

According to this https://68kmla.org/bb/threads/ati-radeon-9250 … ls.51352/page-2, the ST ROM is also 1 Mbit, but is limited to 512 Kbit due to defective cells. Maybe others have failed as well?

Not sure but the bios it’s less than 128kb anyway.
I do not know how to check if it failed or not with the clamp and the T48.
As said it won’t work, probably just like trying to update a SPI soldered on a motherboard without stand by power.

Mamba wrote on 2026-07-12, 11:43:

Not sure but the bios it’s less than 128kb anyway. I do not know how to check if it failed or not with the clamp and the T48. As […]
Show full quote

Ydee wrote on 2026-07-12, 10:35:

According to this https://68kmla.org/bb/threads/ati-radeon-9250 … ls.51352/page-2, the ST ROM is also 1 Mbit, but is limited to 512 Kbit due to defective cells. Maybe others have failed as well?

Not sure but the bios it’s less than 128kb anyway.
I do not know how to check if it failed or not with the clamp and the T48.
As said it won’t work, probably just like trying to update a SPI soldered on a motherboard without stand by power.

Remove the Flash from the board, i had no good experiences with it using the clamp. You are powering the whole 3.3V rail of the card with it.