How to upgrade the bios of an Intel SE440BX2 motherboard?

I have an old Packard Bell Pentium II 350 desktop.

I just found that its motherboard is an Intel SE440BX2 which supports
PentiumIII450 and 500.

So I found a used PIII450 from a broken machine and replaced the old PII
350.

It works fine. Only one problem, when the machine starts up, it seems that
it recognizes the CPU as a PII 450.

I downloaded the latest BIOS update from Intel, but it doesn't work.

Packark Bell's web site is awful. Just cannot find the appropiate BIOS.

Any one can help?