After I installed this card in a Mac G4 running OSX 10.3.5 the computer would no longer sleep. If put to sleep, the machine immediately woke up again. After the card was removed, the computer again operated normally.In response to an email query, IOGear sent me the following reply: "Thank you for contacting us. Your problem is an Apple related issue in which some Macs will read the card as an active source of information, even if the card is not in use and can prevent the computer from going to sleep. Sometimes installing the card in another PCI slot solves the problem, otherwise, I would recommend you return the card to your place of purchase. I apologize for any inconvenience."I followed IOGear's advice, and tried the card in each of the computer's four PCI slots. The problem wasn't solved, and I subsequently returned the card to Amazon for a refund.