This post will be a bit off topic... but still on topic.
I found a dead ISA only OPTI 493 486 motherboard
The corrosion damage. (I'm not the one who has scratched the board)
The attachment Corroded tantalum cap.JPG is no longer available
A Shuttle HOT-403 with a boring AMI BIOS dated the 6th of June 1991 and a non working motherboard with a MR BIOS... This is an opportunity to see if the MR BIOS brings any profit.
Here is a picture showing the two motherboards side by side. Most of the stuff match except for the OPTI F82C206 integrated peripherals controller (where the CMOS lives) versus the UMC UM82C206L. These chips are both copys of the Chips 82C206 from the NEAT AT 286 chipset so any BIOS that works with one should work with the other. Notice the HOT-401s serial number 91-00321. 😀
The attachment Shotte HOT-403 + dead motherboard.jpg is no longer available
Well was the MR BIOS still alive? ... yes 😀
The attachment MR BIOS.jpg is no longer available
Did it bring any profits? Not much but I could now choose at what rate the memory is beeing refreshed and that did bring a minor improvement.
Above: AMI. Below: MR BIOS. The CPU is a vanilla 486 DX2/66.
The attachment HOT-403 AMI + MR BIOS.jpg is no longer available
I will upload both the 386 and 486 OPTI 391/493 MR BIOS images later. Perhaps they are one and the same, who knows.
Edit
Corrected some faulty information
/Edit
New PC: i9 12900K @5GHz all cores @1.2v. MSI PRO Z690-A. 32GB DDR4 3600 CL14. 3070Ti.
Old PC: Dual Xeon X5690@4.6GHz, EVGA SR-2, 48GB DDR3R@2000MHz, Intel X25-M. GTX 980ti.
Older PC: K6-3+ 400@600MHz, PC-Chips M577, 256MB SDRAM, AWE64, Voodoo Banshee.