BIOS Updates forum

Hi there,

I would like to know about substituting BIOS roms for motherboard.

for one, I am interested as to why my motherboard has a 2MB chip when the bios files are only 256KB.

Therefore, is it nessecary to use a 2MB chip? can you use say a 1MB chip?

the chip in question is a Mosel V29C51002T

Thanks all

2MBit / 8 = 256kByte
1MBit / 8 = 128kByte

you need to replace the bios chip with a 2MBit chip.

Oh, of course - I was reading the spec sheet as 2MByte for some reason...

I got another 2MBit/256kByte chip (SST) and it programmed fine.

Only problem is I still get the 'Can't write ESCD' error I was getting which made me think the previous chip was going bad.

Guess there's something wrong with my board...

At least I'm not confused about the chip sizes anymore

Writing the ESCD- and DMI-area requires software support: The Bios needs to know where the area is located in the flashrom and how to rewrite it.

Maybe it's an option to Clear CMOs and try again.

What board are you using? Was the Mosel chip installed from the factory or was it already a replacement chip?

It's an Asus P2B - the Mosel chip would appear to be the original - it had a phoenix sticker and an Asus sticker on it (informing me that it was bios version 1008) - although the board was 2nd hand when I got it.

I had originally been using 1008 and the old chip until I tried to use windows XP, and the COM ports didn't work, turned out you have to use BIOS version 1009 or higher to fix that, so I flashed with the Aflash program from asus website and the latest ROM, 1014.003

The board worked fine for a few weeks, then I started getting an error on startup:

"Hardware monitor found an error, please enter power management setup for details"

When I did look in there, all the voltages were completely wrong, ie: if they were actually what it said they were, the board should not be working at all!

I checked with a voltmeter and everything was normal, so I figured the hardware monitor was broken for some reason. Setting all the voltages to "ignore" cured that problem, but then I started getting problems where the ESCD would re-update every single boot and then eventually just "Error -- Can't write ESCD"

Googling that, I was told that my flash chip may be going bad, so, after looking around I found a dead motherboard with a similar chip (the SST I am now using)

I hotflashed the 'new' chip to the P2B bios (including bootblock) with Uniflash, which worked, but I still get the hardware monitor and ESCD error.

I also replaced the battery which was at 2.9v, but that made no difference (didn't think it would anyway) - and cleared both BIOS settings and ESCD/DMI several times

So I'm starting to think that my board is just going bad

Does your board have a hardware monitoring chip at all ?

Asus had two P2B, one with and one without hardware monitoring chip. There's a special Bios for the P2B without.

ftp://ftp.asus.com.tw/pub/ASUS/mb/slot1 ... 14nh03.zip

I'm not sure, but the hardware monitor worked fine for a while and with the old 1008 BIOS, so I guess I have one.

Maybe the board is toast. Check for leaking capacitors or other visible damage.

Yeah that's what I was thinking too... that the board may be faulty

The capacitors all look fine, although I guess that doesn't guarantee they aren't bad

On close inspection though some of the PCB tracks seem a little corroded, I guess that wouldn't help