I have a strange issue on one a 386 system, I have swapped a i386 DX25 cpu and replaced it a DX 33, however the system bios still says it’s a DX 25. Am I missing something here ?
Yes, you're missing the crystal oscillator, which is located on the motherboard. 😀 Depending on your specific board, it might be easy to replace or very hard (since you have a socketed CPU, I suspect that the oscillator is also very easy to replace in your case).
Your current oscillator runs at 50 MHz (and the CPU runs at half that speed). You need a 66 MHz oscillator for a 33 MHz CPU and an 80 MHz oscillator for a 40 MHz CPU.
This is how an easily replaceable oscillator looks like on a typical 386 board:
2 x PGA132 / 5 x Socket 3 / 4 x Socket 7 / 6 x Super Socket 7 / 5 x Slot 1 / 3 x Slot A
5 x Socket 370 / 5 x Socket A / 1 x Socket 478 / 2 x Socket 754 / 3 x Socket 939 / 4 x LGA775 / 1 x LGA1155
Current rig: Ryzen 5 3600X
Backup rig: Core i7 7700k
