Nice tests. You have actually gotten to the same results as I did with my benches (I used a P100 as I don't have a P133 Overdrive for the Socket 5 boards).

Socket 5 & 7 Motherboard VGA Benchmark comparison

mpe wrote on 2020-06-03, 14:10:

Thanks at least I know what it is. I could find any useful stuff about the board (BIOS, manual).

However, I found datasheet for the chipset with register info. So perhaps I can write a tool to compensate lack of BIOS options with some programming...

Is possible to share that datasheet? i'm interested and also got an OPTi Viper-M board (Octek Rhino 5)