Pro Tools 8.1 Magma expansion chassis help

[The Rudy Mah]

Hey there digidesign / avid forum dwellers.

After quite a while of searching these and many other forums / troubleshooting things I've decided to throw in the towel and ask for a little bit of help with getting my PT HD rig running on my macbook pro.

so here is the story:

I have a PT HD2 system, running a core and process PCI card that are in a magma 4 slot PCI - Express 34 card expansion chassis on a 2.2 Ghz Intel core 2 duo (w/ 2gb 667 mhz ddr2 sdram) running snow leopard (10.6.4) and an ice cube 250 Gig HDD (FW400)

after having problems with an error coming up regarding lack of CPU power even when i only had one track with no plugins in the session i decided to do a completely fresh install of Snow leopard and protools 8.1 .. Since doing that the CPU error message seems to have gone which is great, but I'm still having dramas of when I play back audio it plays about 2 seconds of it, then even though the timeline keeps moving all I'm hearing is a loop of the 2 seconds that has some kind of digital white noise / static playing over?

I only have the plugins that come with 8.1 installed, I have the session setup pretty standard (buffer size is ... is it 1024? .... the next one up from 512... I'm using one less processor than my maximum.. i.e. 1 processor and have the system usage set on 80%)

The only thing that i think could be the weakness in the chain is the Magma expansion chassis as I couldn't find any compatability info with Leopard or PT 8.1 ..

I had it all running flawlessly on 7.4.2 running on leopard with all my waves plugins etc and the exact same hardware setup as i do now, but as soon as i changed to Snow leopard and 8 , or higher ( I've tried all of the PT 8 versions and they all do the same thing) ,

just wondering if anyone has any info , or has a similar setup to me as i can't seem to find anything anywhere..

any feedback is greatly appreciated .

Cheers

Rudy