@PcBytes, hi mate, just wondering why you would want to change the bios on an s3 trio64 chipset? I use a Diamond S3 Trio64V+ combined with a Diamond Voodoo 1 in my Pentium II 333mhz rig and I've never really had any issues with compatibility using the S3.

Mine is a plain 64 chipset.And,I've seen BIOSes on video cards nicer than the one it has such as the Number Nine 9FX.(it has a blue line at the top which reads"Number Nine Vision Technology,Number Nine 9FX,(a music note)Now I'm 64....")
Also,you say you have a Diamond S3 Trio 64V+.What text does it display before the system BIOS?

@PcBytes, I just connected up the PC to have a look for you and strangely it's giving me a "no vga signal". After 2 seconds it then gets a signal and starts testing the ram etc. By that stage I've missed the initial graphic card information at the start. I have a feeling it's got something to do with the monitor being connected to the voodoo 1 so what I'll do soon is remove the voodoo card and have the monitor plugged directly into the s3 card. I'm sure this will enable me to see the bios information. Once I've done this I'll take a photo for you.

@PcBytes, I disconnected the Voodoo 1 and ran the pc with just the S3 but it jumps straight to the main bios loading screen where it tests the ram. I'm unable to view which bios the card is running sorry 🙁

Are you using a CRT?If yes,switch to a LCD,I had luck seeing the bios info on my S3 using a LCD.

@PcBytes, yeah I'm using an LCD. Strange because my other retro builds using a Geforce2 TI, Voodoo 3000 and ATI X800 Pro all show the bios on startup using this same monitor. Maybe it's something to do with the motherboard...