Ok, I've discovered that for some reason the 9600 isn't liking some of the PCI cards that I've installed. I've now got the TT working in slot 4 (2nd to last). You're right, they're actually numbered 0 to 5, so in that case I meant that the TT wouldn't work in slots 4 and 5.

I took out some of the PCI cards and the TT is working in slot 4. Haven't tried slot 5 yet.