Running under XP-SP2, when we use a single disk, DMA is active and everything is fine. When we connect a second physical disk as slave on the same Main IDE Channel, both switch to PIO. We bought a new 80-connector ribbon and tried several different slave disks. No change. FYI, both dvd readers are on secondary channel.

Try one of these configurations: primary master = HDD w/OS primary slave = optical reader 2ndary master = optical writer 2ndary slave = 2nd HDD primary master = HDD w/OS primary slave = optical reader 2ndary master = 2nd HDD 2ndary slave = optical writer And make sure to change the master/slave jumpers as necessary "And that's the fishing line, because Sharkboy said so!"

To add to the above response by jam, when using Master/slave jumper settings it does not matter which connector you use on which drive. That assumes you ARE using an 80 wire cable. Sometimes it is easier to connect the Master drive on the center of the IDE cable.

Thanks for the tip, we'll try these combinations and report back. BTW, we've been using the setup described in the first message for the past 2 years without a hitch. The issue described appeared all of a sudden.

You may need to re-install MBoard chipset drivers in that case.

The issue was solved a bit by chance. We went into the BIOS to see whether DMA could not be forced from there. As it turned out, we could not since we were faced with a Department Store Tower, nevertheless with a Gigabyte MB and AMI BIOS, going back to 5 or 6 years ago (Pentium 4, 1.7 Ghz). It's at that point, in the BIOS, that we noticed that the two disks were set to User-defined. When we changed this to Auto, the problem was solved and everything was back to normal as it was before we ran into the defective connector issue which started all. BTW, is there really that much of an improvement in throughput when you mix DVD reader and disk? Thnaks to all for the suggestions which put us on the right track.

You will never get any improvement when mixing harddrives and optical drives on the same cable. However, most modern sytems allow each drive to run at it's maximum capability. Look in Device Manager to see what DMA mode each drive is running in. That can be found under advanced setting in the IDE controller listing. Should be a listing for Primary and one for Secondary.