CLICKS and POPS in 10.5.4 with 424e card?

[rolbenne]

i've just bought a new macpro 3.2 8 core, and i'm getting pops everywhere, with the pci424E... not only in DP but in OS apps as well.

i'm currently jumping back and forth between my new macpro, and my old computer (PPC 2.7dual G5 with a motu424).

these 2 computers are connected to the exact same hardware... with the only difference being the pci for G5 and pci-E for macpro. When on the macpro, i'm getting clix everywhere. listening through any audio source. so, through i tunes, or digital performer, or quicktime (i have pci424 as default output in finder). i can switch back to my g5 computer. connect the 2408 and everything is fine. all my setting are identical in the motu pci audio setup. the clix on the macpro sound like clocking issues, except i get them even when just running it on internal clock. how can i fix this?

here's my exact setup, and audio flow.
mac pro_ to pci 424e_ to 2408 mk3_ analog out Bank A channel 1 and 2 to tascam dm24 on 1/4", to speakers.
for the past few years, i've been running this exact setup and it's fine, i'm receiving clock from dm24, but now that i have clicks on macpro, even if i switch the 424 to internal clock, i get the exact same clicks. AND AGAIN, i can simply plug the audio wire over into the 424 of my G5 ppc which has the exact same setting on it's 424 config. and i get no pops.