MR816 and Dell desktops incompatibles ?

Recently I’ve purchased a desktop computer DELL XPS 800 and a Steinberg mr816 csx interface.
The computer has not any firewire port, so I had to install one via PCI-express.
This firewire card has not the chipset Texas Intruments that Steinberg recomends. The O.S. (Windows 7 64 bit) recognices the MR816 but I can’t play any sound, for example with the Windows Media Player I’ve got the typical message “Windows Media Player cannot play the file because there is a problem with your sound device. There might not be a sound device installed on your computer, it might be in use by another program, or it might not be functioning properly”
In the devices manager I checked the firewireport without obtain better results.
I 've installed the MR816 in my old DAW with firewire ports and Windows XP whithout problems
Could I solve this problem just purchasing a firewire card with Texas instruments chipset or
maybe the DEl XPS doesn’t permit install any other sound device via their only two free slots pci x1
Sorry about my poor english level
Please, can you help me ?
I wasted a lot of hours whit this trouble
Thank you so much for your help

OS Windows 7 64 bits
Audio interface Steinberg MR816

i recently bought a Dell XPS 8300, too. My PCIe-Firewire card is a EXSYS EX-16450h with TI-Chipset.
The MR816X works perfectly and with very good performance.

I look forward to receiving the PCI express with TI chipset soon