Hi, sorry the bad title, i dont know how to explain very well my problem

I have some retro PCs for testing, 386SX40, IBM PS/1 486DX4-75, Celeron 333mhz and Pentium 3 1ghz, and this laptops, Toshiba 486DX4-75, Toshiba laptop Pentium 100

One thing i really like is to copy CD games like Megarace, Mad Dog McCree, Cyberia, etc to HDD to avoid using CD, and i have problems with the IBM 486. The games videos run bad, like accelerated 1 or 2 seconds, then slowdown, or freeze, etc, but works fine in other machines!

I have a 20GB 2.5" HDD i use for all test, have EZdrive overlay, but i tested other HDD and one 4GB CF

I tested the same HDD in all machines, the results

386SX40, Celeron, PIII and both laptops - Fine, all games load OK, videos OK - 0 problems

IBM PS/1 - BAD all the problems i say before

Beside this, the IBM works great, and the games from CDrom run fine

Sadly the IBM bios is HORRIBLE no options to configure, and is not possible to disable internal controller, and i dont have any ISA controller that have a secondary IDE or is possible to consigure as secondary

I dont know what else to test, any ideas are welcome!!

thanks