however the throughput of either when attached to a normal PCI bus as would be typical on most deskop computers will be all of 133MB/s the limit of 32 bit 33MHz
the same as internal IDE HDDs
(to better that would require a 64 bit PCI slot)
but that doesnt matter since a single HDD has a typical internal transfer limit of 50 to 25MB/s sustained throughput (with burst at 100 > 133MB/s)
As the Disc Spins
@ Lost Circuits
and external HDD performance is actually far worse in application
realworld throughput is going to be in the nieghborhood of 35>25MB/s
depending on a fairly wide range of other factors
Originally posted by lessthanjakejohn @ [H]ardforums
The USB standard is in a state of flux, with vendors often using their
own interpretation of the words "full" and "high". At one point, "full
speed" referred to USB 1.1 operating in a USB 2 port at the 12Mb/s
maximum of USB 1.1. "High speed" referred to the standard maximum speed
of USB 2, 480Mb/s. The USB organization has a statement to the effect
that one should determine what is being stated by a vendor from the
vendor itself if there is any doubt about what is being advertized.
This is important since some vendors were using the term "USB 2
compliant" to mean USB 1.1 would work, while customers were interpreting
it as "USB 2".
The USB standards organization still recognizes that Full Speed and Low
Speed refer to USB (formerly known as USB 1.1) transfer rates, and
High-Speed refers to Hi-Speed USB (formerly known as USB 2) at its
maximum transfer rate.
The USB-IF's naming and packaging recommendations for low- or full-speed
USB products, as listed on this web site state that such products can
carry only the basic version of the USB logo, which simply states
"Certified USB." We state clearly that manufacturers should avoid using
terminology such as USB 2.0 Full Speed, Full Speed USB or USB 2.0. These
formal recommendations were published to the USB-IF membership and
posted on this web site in August 2002.
plus the implementation on the board, the HDD selected, ect
there are SATA external HDD enclosures and SATA controller cards with external posts, they are by far a better performance choice
however as mentioned, external SATA ports arent going to be very common
but I also dont recommend the use of external HDDs at all unless your fully aware of the inheirent dangers
they employ the typical internal drives 3.5" form factor as opposed to the 2.5" laptop form factor which is far more robust
Seagate Proper Handling Guide
Head slap is when the actuator arm/read-write assembly impacts the platter due to a shock such as a tip-over, a tap with a screwdriver, or an overly aggressive shove to get the drive into a bay. This can also occur if you try to scoot the box across your desk while it is running
As a result of the impact, tiny indentations can be formed. The material ejected from this impact is scattered about the disc, and when the drive is powered up the heads will pass over this indentation and the ejected material. This can be the equivalent of running over a bowling ball in a go-cart traveling at Mach 813.
IMO the marketing of external HDDs over emphasises their mobility utility value, without the proper cautions
more comparative form factor information