Topic: Running Fireface 800 with adi8-ds system hanging up

Hi
I am running a Fireface 800 with an adi8-ds through the adat ports, my daw is sonar 8.5 producer 64bit for 16 analog in and out. I am mixing out of the box and my system is hanging up when I get to 14 outputs.
My system is
intel quad core
6Gb ram
Windows 7 64bit
I am using the firewire 400 port on my computer at this time. I am wondering if I get a firewire 800 card to install in my computer will the increased bandwidth solve my problem.
Also any suggestions on a good pcie firewire 800 card would be helpful
Thanks