Hi all,
I'm experiencing CPU spikes and audio dropouts with Fireface 800.

Equipment I use:
CPU - Mac G5 2x2.3 GHz (PCI-X) with 4GB RamJet and 2 fast hard drives
Software - Mac OS X 10.5.8 / MOTU Digital Performer 7.2.4
Audio application - mixing / production studio with Fireface used as an interface and a summing unit, so all 28 computer feeds and 10 analogue audio inputs are always in use.
Other hardware: two UAD-1 cards (PCI), Universal Audio powered plug-ins
the studio runs on an industrial-grade voltage stabilizer / power conditioner
no other FireWire devices connected
FireFace MIDI driver not in use

I've tried almost all possible combinations of buffer sizes and other audio driver- related settings and different versions of the FF800 driver and firmware.

Same problem took place with two different models of G5 (Dual 2.3 GHz and Dual 2GHz, both PCI-X) , earlier versions of DP (from 4.5 through 7.2), earlier versions of OS X (from 10.3 through 10.5., and earlier FireFace drivers, with and without my two UAD-1 cards and their drivers and on the freshly-installed OS and DP as well. I've also tried to connect the Fireface with FW800 or FW400 cable, no luck.. The dropouts didn't exist with my previous computer (Dual G4 1.4 Ghz), but started when I've upgraded to G5.

Problem description:

Randomly, the CPU activity (according to the application meter and to the application's response) grows without any reason and causes a CPU spike with about a second of audio dropout. The second always spike appears in less than second after the first one, so the pikes are kinda doubled.
The dropouts occur randomly and absolutely unexpected: I can have a day without problems with heavy project or I can have dropouts every 5 minutes with a 4 track project. The project can be playing back or idling in the background, it doesn't matter.

However, the dropouts only seem to happen when I run DP with multiple outputs; I never had problems with software such as iTunes, Quick time, Final Cut, VLC etc. But I didn't use more than 2 audio outputs with other software either.

I've found other FF800 users that experience similar problems with other applications, on both Mac and PC platforms.

So here are my questions:

1. Is this issue common with FireFace 800?
2. Could my FF 800 be defective?
3. Can I get rid of the dropouts by purchasing a PCI firewire card for my mac instead of connecting FF800 to the on-board FireWire? If so, what card should I purchase?
4. Does anyone have a positive experience with this combination of Digital Performer, FireFace and mac G5?

Thanks in advance.