September 15th, 2004 05:17 AM
The reason you can probably see better performance when you have the HDD and DVD-Burner on different IDE channels is because of how IDE works. Basically, when you have just one HDD on the IDE cable, it gets to use all of the bandwidth. When you have two HDD's, they have to share the bandwidth.
In reality, there are enormous electrical issues that adding another drive complicates. Especially since PATA and your IDE HDD were originally meant to transfer things at like 3MB/s back in the day when it was created. Today, they are trying (not very successfully) to squeeze 133MB/s out of it, although getting to 66MB/s was a big enough challenge in itself. This is where SATA comes in to fix all of the problems of this ancient, pushed to the limits, PATA standard...
In SATA, ach drive gets its own dedicated cable. No more worrying about how another HDD will impact impedence and how any combination of HDDs will affect signal bounce/reflection. Less clock-skew issues. Less interference. Better performance. Also, less space is taken up, since SATA only has 4 wires...
Anyways, if at all possible, especially when using multiple HDDs, put only one drive on a cable, and nothing else. Just get a single cable for this. But in your case, just seperate the HDD from the CD-ROM/DVD drives. That will make it easier since they won't fight for time on the cable (since they are on different ones) to talk to the IDE controller (which would have to send the data back up the cable to the DVD Burner if they are on the same cable, preventing the HDD from sending more data at that time) when you are burning a DVD at high speeds. Otherwise, group the PIO together and UDMA together. The cable has to go to the lowest speed of the thing connected to it, with PIO being the worse (IIRC) especially for a HDD.