The theoretical limit of 32-bit PCI slots is 133 MB/S. I read somewhere that the real limit is somewhere around 106 MB/S, I guess there is always some unaccounted for overhead. This means that all devices connected to 32-bit PCI slots (ATA, SATA and SCSI controllers) are limited to this speed.
However, to reach this transfer speed you need at least 3 to 4 disks, so if you only have 2 then there is nothing to worry about. The most important thing to consider here is that this limit refers only to transfer speed, which is what you need when working with large files, like watching/editing several simultaneous video files, or copying large files from one disk to another.
On real life use, on the other hand, seek times are more important. Operating systems and applications need to find, open, read/write and close lots of files, and in this kind of operations transfer speeds are not as important as seek times, and this is where SCSI has the advantage. Most 7,200 rpm ATA and SATA drives have seek times of aprox. 9 ms. The new 10,000 rpm Raptors have seek times of 5.2 ms. SCSI 15,000 rpm drives have seek times of 3.4 - 3.6 ms.
One more thing to consider is that RAID 0 improves transfer speeds, but worsens seek times. So for your system/applications drive its better to have a single 15,000 rpm SCSI disk, and use RAID for your data, especially if your work with large video or database files.
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It's not important to know all the answers, as long as you know how to contact someone who does.<P ID="edit"><FONT SIZE=-1><EM>Edited by gaviota on 04/24/03 01:33 PM.</EM></FONT></P>
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