Greetings, I recently bought one of those PNY AMD 5x86 133mhz processors I can't get it to work at full speed on my 486 system, the CPU is not being recognized by the motherboard, there is a jumper that selects the CPU speed (25, 33, 40 or 50mhz) and I can only make the 5x86 work selecting the 25mhz setting, the processor then runs either at 3x 75mhz or 4x 100mhz. I have been reading previous topics on this forum about this problem and as far as I can tell my only path forward is burning a new Bios Rom and swapping it for the one in my motherboard.
As the topic title says my mother board is an Aopen V433s and it has a single SiS 86c461 chip:

The Bios is an american megatrends, the Bios string and the Bios chip are:

As I have said before I've been looking for a ROM compatible with this motherboard but I don't seem to be able to find one, can anyone help me? Thanks in advance.
Edit: I forgot to mention that I have tried all the dip switch setting from these links and setting the cache to write back or write through, I have also tried disabling both L1 and L2 cache and nothing works:
https://web.archive.org/web/19980703090938/ht … switchreve.html
https://web.archive.org/web/19980703090959/ht … ddsettings.html