If you are having difficulty getting PCI-324 communication with the Yosemite Blue & White G3's or G4, you need to install the latest PCI-324 Driver that was updated for these machines.

On our downloads page you can choose MOTU Audio drivers. Download MAS 1.5, and run the Easy Install. From that installer you can also custom install the PCI-324 driver. Restart and then try configuring the PCI-324 Console. In the Extensions Folder there is a MOTU folder. In that folder you can get info on each item and make sure you have the latest. After installing the latest PCI-324 driver you should have Motu Audio System 1.5, Motu Public Objects 1.22, and PCI-324 Driver 1.3.

There are currently two firmware updates that you may want to consider downloading from Apple's Web Site which will improve performance on your Blue G3. One is for the Blue G3 itself,
asu.info.apple.com
and the other is for those of you with an Adaptec card in your Blue G3.
asu.info.apple.com