Mobo: SYL8884PCI - EIO (it's a good "modern" board)
CPU: Intel 486 sx 25, nothing fancy
BIOS setting: fail safe.

Speedsys gives me a stellar score of 2.36! (This value is worse than the 386 DX 40 benchmark position.)

I run Ultima 6 (released in 1990, approx a year after 486s were released), and watch the intro carefully. It's where the kid is watching TV. On every board I've tried this game on, the "TV intro scene" runs too fast. But not any more! It looks about right, now that the board's BIOS is in fail safe mode.

(If only I had a copy of one of @Amigaz's favourite games, Wing Commander, I could see if this "best on a 386 DX board" game runs OK.)