I have a particular ASUS board model P2E-M that I like and have had for years. It's a great little micro ATX with a nice mix of features and is my go-to board for testing. I found some decently priced units on eBay recently so I bought another two as spares.

The one I already owned was already flashed with the latest 1010.004 BIOS but the new ones I'd gotten had the stock version 1008. I have no problem flashing my original unit so I used the aflash utility provided by ASUS just as I had done previously. But something went wrong. The flash succeeded but the system would POST and then hang just prior to detecting any peripherals. No amount of rearranging of parts would allow the system to proceed past this point.

I had backed up the original ROM and still had working boards so I experimented with the chips I had with the different BIOS versions by swapping them after a successful boot and hot flashing.

Reflashing the BIOS to 1008 fixed the problem but reflasing to 1010 always produced the same issue; I tried flashing with and without updating the Boot Block and ESCD with no change in behavior. Finally I examined all three of my chips and found that my original board which took the flash fine has an Atmel AT29C010 BIOS chip while the one which would not flash properly is a Winbond W29EE011. I don't know what the significance is but aflash would appear to succeed but somehow fail to correctly flash the Windbond chip. Interestingly, the Atmel chip isn't even detected properly by aflash and is identified as "Unknown". I don't know how I flashed this chip originally but it couldn't have been from the aflash tool linked on ASUS's support page.

I then tried using Uniflash instead of the aflash tool provided by ASUS and the Winbond chip was finally working. I tested this several times with both Winbond chips as well as reconfirming that aflash was the problem.

I don't know what the issue is between aflash, Windbond, and the latest BIOS version, but this has been a major headache. I don't like hot swapping BIOS chips in a running system but this was the only way to properly investigate this issue.

So when in doubt or if you're having trouble getting a flash to take, try Uniflash instead of aflash.