I have a going on 7 year old ASUS motherboard. Works fine. What I think I heard though about newer motherboards and computer is that the slots are shared. They seem not to be separate. Not sure what that means, but extra slots are PCI-3 1X slots (small). And most of the time, made for newer cards. Glad I use a USB audio interface. There is no room for bigger (deeper) cards and such. Ran into that problem even with my old computer and some video cards when having a audio card in the slot below. Now there is add-on wi-fi and whatever else also. Good luck, but heat would be a concern with anything like that also. That is just the way they make the newer motherboards now, so have to be aware of whatever it is they are coming out next. If there are newer short-profile (depth) cards, then or when they come out, then that is what you will have to use I guess. That is at least the way I understand it right now. I know my new computer (gateway) compared to my old computer is - cheaper made ( but it is a cheap computer anyway - my old one was not all that expensive either.) Those engineers keep changing things around, and well, the cards made for them - that is probably going to be a mystery for awhile also.

 I built a PC last year that I'm still trying to work the kinks out of. Pretty stable for the most part except after about an hour working on a project, I'll get some drop outs and have to restart X2 other than that pretty stable with 3 powercores, 1 UAD-2 and on occasion my Focusrite Liquid mix. On a Gigabyte Z68.

 I'm still using the onboard VIA 1394 chip for my firewire and I also heard that TI chipset cards are recommended. I've tried 2 pro audio recommended PCIe cards with TI chips. The Lindy card and the SIIG. Both install but intermittent connection and no funtionality. The slot I had reserved for it had only one other device sharing the IRQ.
 I was reading that TI chipset firewire needs its own IRQ. Not sure if that's the case.

 I'm thinking that if that TI chipset PCI card you have may be the conflict. If you have onboard I would give it a try with the TI card removed.