I have had the same problem with 2 different pc's. one has a gigabyte 686BX motherboard and the other is a PCchips 748lmrt AT motherboard. When a second hard drive set as slave is installed the hard disk controller in device manager shows that there is a problem and states that the device is not present or not working properly. The jumper settings have been checked and double checked .. I've tried different ide cables but still the problem is there. They are both detected in the bios as primary master and primary slave. one thing different on the gigabyte board is that in the bios the primary master is a 3.2 gig drive but when the pc is running in my computer it only shows as a 2 gig drive. both drives show and work ok in my computer but the pc's run very slow. just to clarify .... 2 pc's ..four drives ..2 different drives in each pc ..any thoughts?