Just an update on this issue!
For those new to the thread, the issue is than when you use a PCI SATA controller, games that probe IRQ2 for a MPU401 interface, like Gateway, will crash.
I'm re-visiting this project and currently out of all my SS7 boards, ONLY Gigbayte boards have ACPI hard-wired to IRQ 9 and therefore a MPU401 on IRQ2 will cause issues.
The boards I have test so far and work fine are:
AOpen AX-59 Pro (ACPI can be disabled in BIOS)
Iwill AX100 (ACPI can be disabled in BIOS)
DFI K6XV3+/66 (ACPI can be disabled in BIOS but also works with ACPI enabled when in PnP options IRQ 9 set to ISA and PCI slot that holds PCI SATA card is set to IRQ 3 or 4 with COM ports disabled)
ASUS SP97-XV (SIS chipset, No option but also no conflict. Maybe doesn't have ACPI?)
Board I tested that DO NOT WORK are:
Gigabyte GA-5AX
Gigabyte 586ATX