For the old card sis/savage/via/others you have to:
1) X -configure with old X (like 1.4.x) to probe all vga cards
2) X -configure with your X with Option NoInt10 yes enabled only to the
old cards like sis/savage/etc
Xorg 1.7.x+ has bug with systemcall Int10, an a lot of SiS and VIA old cards
I am trying an experiment and getting dual monitors working on a system
using two video cards. the video cards are the onboard S3 Savage and a
S3 Virge PCI card. lspci yields:
00:05.0 VGA compatible controller: S3 Inc. 86c325 [ViRGE] (rev 06)
01:00.0 VGA compatible controller: S3 Inc. VT8375
