I recently built a GIGABYTE GA-EP45-UD3P based quad core system for home recording. Everything is working perfectly except the FSM. The device shows up under System Profiler -> FireWire as FIRESTUDIO_MOBILE, but the firewire light flashes between blue and red. I have installed the latest drivers from PreSonus (v 3.4.2 beta) to no avail. On my MacBook Pro, the PreSonus Snow Leopard beta drivers work just fine. I suspect this could be an issue with my firewire interface. I have tried using the built-in firewire on the mobo as well as a TI-based PCIe interface... no luck. Any help would be greatly appreciated. Thanks.

I spotted a difference between the MacBook Pro and the desktop: the desktop is running in 64-bit mode.

Also found these in the system log:
- Can't load /System/Library/Extensions/PaeFireStudio.kext - no code for running kernel's architecture.
- Failed to load /System/Library/Extensions/PaeFireStudio.kext - (libkern/kext) requested architecture/executable not found.

I guess the PreSonus driver isn't 64-bit ready...

It looks like PreSonus is working on a 64bit version:
http://forums.presonus.com/showthread.php?p=52766