First off, if you can't fix it, don't throw it away. Give/sell it to someone who can.

Did you try to disable the cache via BIOS or jumper?
If the cache is really bad there is no wonder you run into memory errors still using it, or are you getting the himem.sys error despite disabling the cache?
You can visually inspect the area where the cache chips are soldered and try to clean it (e.g. with an old toothbruch).
Replacing the cache chips with DIP sockets is not this complicated for someone having the right tools and experience, or does the system use QFP chips?

I thought the board disabled the cache. There's no BIOS setting for it. I will try the AMI Ctrl+Alt+Delete+- method next time. The board looked clean to me, I've removed dust with compressed air, but it didn't change anything. Yes, these are QFP chips, I will try to find replacements, I've found someone willing to help me with the soldering.

Since this is one of the few references online about this particular error, let me share how I fixed it on my 386 motherboard.

As it turns out, the soldered PMOS barrel battery (beneath the J1 header) sat just next to the cache memory (bank 0) so damage caused by battery leakage was my main suspicion. At a glance, the battery had only leaked a tiny amount, with very little making onto the PCB. However, some damage, as it turned out, was hidden in clear sight.

The first fault was the resistor at R2, where one of its legs had gotten completely corroded away.

The second fault was with the IC socket at U4, the fourth of the cache memory 28 pin sockets. When pulling the chip out, it was clear that green corrosion had ruined four of the pin slots. Luckily, no corrosion had made it onto the IC legs.

Desoldering and replacing the above two components got the motherboard's cache memory back to full working order! The lesson here is to very thoroughly inspect every component in the vicinity of a leaky battery, however minute the leakage may appear.

Good job 😀 what will you do to replace the battery?

There is an external battery header visible in his pics, so hopefully the answer is "use that"

My apologies, I didn't see your responses until now!

Yes, I did eventually spot the battery header and built an external battery pack with 3xAAA batteries. Photos and write-up over at TinkerDifferent.

bigwhoop wrote on 2022-06-21, 22:16:

My apologies, I didn't see your responses until now!

Yes, I did eventually spot the battery header and built an external battery pack with 3xAAA batteries. Photos and write-up over at TinkerDifferent.

Nice. Is that the voltage it’s supposed to have? 4.5v?

Sphere478 wrote on 2022-06-21, 22:33:

bigwhoop wrote on 2022-06-21, 22:16:

My apologies, I didn't see your responses until now!

Yes, I did eventually spot the battery header and built an external battery pack with 3xAAA batteries. Photos and write-up over at TinkerDifferent.

Nice. Is that the voltage it’s supposed to have? 4.5v?

Thanks! I'm not sure what voltage it was designed for. I have not been able to find complete technical documentation for this motherboard.

bigwhoop wrote on 2022-06-23, 02:50:

Sphere478 wrote on 2022-06-21, 22:33:

bigwhoop wrote on 2022-06-21, 22:16:

My apologies, I didn't see your responses until now!

Yes, I did eventually spot the battery header and built an external battery pack with 3xAAA batteries. Photos and write-up over at TinkerDifferent.

Nice. Is that the voltage it’s supposed to have? 4.5v?

Thanks! I'm not sure what voltage it was designed for. I have not been able to find complete technical documentation for this motherboard.

Looks like a varta is nominal at 3.6v

It seems to be a 3S pack (three cells in series)

https://en.globtek.com/nimh-battery-safety-no … d%201.3%20volts.

“NiMH Voltage
The discharge voltage profile of a NiMH battery is considered “flat” (see Figure 3.7.2 C/10 Discharge Profile @ 25°C) and varies with the rate of discharge and temperature. As a fully charged battery is discharged the voltage begins at about 1.5 volts followed by a sharp drop to around 1.3 volts. The voltage remains between 1.3 to 1.2 volts for about 75% of the profile until a second sudden drop in voltage occurs as the useful capacity of the battery begins to deplete. At this point is where the discharge current (or load) is terminated at a safe voltage level“

So full charge per cell is 1.5v

So three 1.5v AAA batteries in series actually does fall within the charge profile of a 3.6v varta.