Crackling Then Distorted Audio, is it powercore or audiophile? Options

[backini]

When I play back a busy arrangement in Logic, after a while I start to get slight distortion, then crackling, then severe distortion over the audio. I suspect its some sort of conflict between my powercore element and my audiophile 2496 as this started to happen on my G4 just before I upgraded, now I have a G5 and I've started to get the same problem although the only thing in my machine that isn't new is the powercore pci card. I would put it down soley to the powercore were it not for the fact that when I switch the audio drivers to inbuilt audio, the problem disappears, pointing at the sound card as being the culprit. I have followed both TC and Maudio's advise (re-installing latest drivers, moving around to different pci slots) but had no luck. Any help would be much appreciated as I've spent days scanning forums for similar issues.

previous system: G4 dual 867, 1 gig ram, audiophile 2496, powercore element, Logic 7.1
Current system: G5 dual 2 gig (pci-x), 3.5 gig ram, new audiophile 2496, powercore element, UAD-1, logic 7

[lepetitmartien]

I was about to propose to switch between the pci slots but you tried it already…

When it's cracking it's 90% of the time something funky in the bit/KHz definition somewhere… Double check everywhere (logic, drivers, sound prefpanel, audio midi setup, everywhere)

I'd install the CHUD tools from the developers part of your OS X install DVD, then into the system preferences, I'd open Processor and uncheck "nap" to see if it happens still.

Still on the system side, trash the system audio cache as the preferences of audio midi setup (you'll have to reconfigure after restart), and check the RAM, in case it's fishy (CD apple hardware test).

How high is the CPU when it happens?