From: David Gillett [SMTP:[log in to unmask]] << CD-ROM drives read data at a fraction of the speed that modern hard drives are capable of. As a result, many early IDE/ATAPI CD-ROM drives implemented only the "PIO mode 1" level of IDE interface. And on IDE controllers, that meant that any other device on the same channel was also limited to that PIO mode, even if it was capable of faster modes. Things have changed. Modern CD-ROM drives support higher PIO modes, even though they generally can't take advantage of them. And UDMA controllers (which can handle IDE and EIDE drives) allow different modes for each device instead of a single mode per channel. So John's advice above is still useful when upgrading an old system or taking advantage of spare parts, but isn't something to worry about if you're buying a new motherboard and/or CD-ROM drive. >> What year would define as Modern CD-ROM? Regards, Alan Geist Do you want to signoff PCBUILD or just change to Digest mode - visit our web site: http://nospin.com/pc/pcbuild.html