I tested this with my ASUS P2B with issues as described. Replacing the capacitors on the Promise card fixed all of my problems.

Can you elaborate on your system details please? Specifically, I'd like to know the following:

1) Which motherboard BIOS are you using?
2) Which firmware are you running on the TX2?
3) Any IRQ reservations or custom settings in the BIOS?
4) Did you install Intel INF v3.20.1008?
5) Which Promise driver version are you using?
6) Which drive are you using with the controller? HDD or SSD?

I might try the card with a different board... I've got two other boards (QDI and Tekram)...

Well I managed to solve my problem. Attached are my results. My P2B is being very picky with CPUs... I am now using a Slot 1 P3 500E, and I'll fiddle with it more to get my Tualatin working. I also changed my PSU.

edit: Just to clarify, the crashing was caused by my CPU or PSU, not sure which, but not the card.

I don't even use drivers in win9x for promise tx2(+) cards. They do 90MB/S+ in dos using a ssd (detected as udma6 on bios post). In win9 running them in compatibility mode falls back to using their own bios which support udma (like in realmode dos).