I suspect this is Apple's fault, but anyone considering buying a board like the UAudio UA-1 for a G5 should consider that they may never be able to usethe sleep function with the board in the slot. Even if you are not doing music, if you write your dissertation on Word and go to the bathroom and find your computer has gone to sleep, and the only way to wake it is to reboot, and your stuff is lost, its not "good times". The workaround was to get a PCI/USB board, but that did not work out. See email from tech support for the USB card maker (a very well known brand) below and further specifics as to exactly what happened.   ------------ start quote ------------------ You may try installing the card to another PCI slot and test again.    However it may not help to solve the sleep problem. It seems that    although the controller itself is compatible with Deep Sleep, yet as    soon as any devices are attached, the system will not be able to    recover from the Deep Sleep function. It appears that this issue is due    more to the PCI bus itself rather than to the adapter. When Deep Sleep    is initiated, the PCI bus and attached peripherals will be powered    down. Yet because the PCI controller is not directly powered from the    motherboard, there is no way to send a signal to the attached devices    to 'wake' them.       This means that a signal can be sent to the attached devices to put    them into a power down status, but no signal can be sent to revive them    from that state. For that reason the USB cards are not fully compliant    with Apple's Deep Sleep. What you may want to do at this point is to    open up the Energy Saver control panel and set the power settings to    "never" to disable Sleep. You may also want to try updating your OS to    the latest rev.   ------------ end quote ------------------ Specifics : I was able to wake the computer from sleep, but only by using the power button on the cpu, and then when it came up, the mouse and kb attached to the USB board functioned and moved. However, none of OS X's system functions (e.g. restart, sleep, shut down, system preferences, force quit) would work. You could select them but then nothing. So the workaround is not a workaround. There appears to be no solution. And Apple tech support refusesto even discuss the matter - saying that if the computer works without external boards then its not Apple's fault. In other words, we the users/customers, are on our own. Perhaps Apple and Uaudio should put warning stickers on their product boxes warning customers.