Another issue we need to bear in mind is that the PCI bus itself only provides a maximum of 133MB/s of bandwidth. With an older ATA-66, or even an ATA-100 drive, that hasn’t been a big issue, because it’s very unlikely that most users would be moving enough data though the bus to saturate it and cause bottlenecking.

With the ATA-133 specification, though, we now have the potential for a drive to burst bits of data at a full 133MB/s, which would completely saturate the bus by itself. If the drive were the only component connected to the bus, then there would be no problem. However, when we start adding in other components like sound cards, network cards, modems, and so on, we’re looking at a serious lack of bandwidth during heavy loading.

What this means is that we may not see the full potential of ATA-133 drives in some cases. For instance, suppose we were playing an MP3, and moving some files over a network. Those activities both require bandwidth, and that bandwidth is now pulled away from the hard drive. While we’re talking about a relatively small amount of bandwidth, and while it’s doubtful that any end user would notice a difference when working in Word or Internet Explorer, it’s clear that we’re approaching a wall with current ATA and PCI bus technology.

For that reason, amongst others, expect to see technologies like 3GIO, PCI-X, HyperTransport, and 64-bit/66MHz PCI trickle down into the desktop segment over the next couple years. These, combined with newer (Serial?) ATA standards, will provide increased bandwidth, and allow for higher speed drives, networking, and higher quality audio and video transfers.