Hi Akhilv1, In the initial testing of this, I discovered that the mp3 module takes a brief moment to start up and play the mp3 file(s) stored on the SDHC card. This made it more difficult to time the process correctly at the press of the power button, because a microcontroller also has to boot and the 3W amp needs to power up as well. I had the best results with the module wired into 5V standby power direct from the PSU. It sits with its red 'ready' light on all the time. The microcontroller is powered by USB, so when the system starts, it turns on and sends one solitary 'low' signal out to Pin 1 of the mp3 module. During sleep, the microcontroller remains powered on USB 5V as this does not turn off as the machine is in S3 sleep. Thus, when re-wake happens, the microcontroller does NOT send out a low signal, and there is no chime played. A workaround can be used without a microcontroller, using a 5V DC relay instead. USB 5V can be wired to the relay to close the ground circuit to the module pin 1. As you stated in your point number (2) above, however, the Apple PSU disconnects the ground when sleep occurs and the chime plays upon re-wake. Unless the PSU 5V standby could be wired to a USB ground, this could possibly be overcome, but I have not tried it. Using a Picaxe or Arduino (or other) microcontroller running on USB 5V is really the best solution that I could come up with. Anyway, thanks for your comments. I'm hopeful that this solution and potentially others that get posted will give us all a chance to have a better Hackintosh as a result. Cheers!