Hello, RME!

I wrote about my issue already. I have 8x2.26 Mac Pro and first series AIO, modified by soldering by official dealer. Despite of modifying, there are very annoying HDD/CPU/GPU-activity noises and hisses.

Very good warkaround was proposed in this forum (http://www.rme-audio.de/forum/viewtopic.php?id=6944), but it seems it is impossible on Apple hardware (due to closed EFI).

It seems that problem somehow related to new processor energy saving options. May be noise surge appears due to voltage ripples then Nehalem tryes to lower (and raise back) power consumption (when CPU load less than 100%).
Also I am wondering if hyperthreading affects it.

I noticed that noise and hiss sometimes disappears (for example at most boot time or when shut down dialog displaying or sometimes for 1 second just without reason). So I started to searh for various applications be able to do some CPU tasks for this result. First I noticed that if I start Plex player noise greatly reduces (althought not dissapears completly), but this is working only when any output of internal soundcard is selected in Plex preferences. So proposed workaround is to run Plex at background (it is not requiring to play something, just enough to stay in menu) and working in Logic.

I am not sure 100%, but it seems many (if not all) other applications using internal soundcard produce such effect. For example it is working to set any output of internal soundcard as default in System Preferences, start browser (Safary and Opera tested), load any video at youtube.com and start playing (and pause it). But some noises are generated all the same due to flash animation.

RME, can you research this workaround, find some dependences and to implement it at drivers as, for example, some CPU tasks or using internal soundcard (if it is required) or something? Or may be it is able to tweak processor halt modes from Mac OS X?