Mark,
First of all, - just in case: there might be a confusion between the width
of the bus in number of lanes (PCIe x1, x4, x16...) and the version of the
PCIe (1.0a, 1.1, 2.0,..)
See, e.g. this Wikipedia article that summarizes it nicely:
http://en.wikipedia.org/wiki/PCI_Express
So, the Transcend card for $13 that I mentioned (see below) is suitable
for PCIe (x1). I am not 100% which versions of PCIe (1.1, 2.0) it is
compatible with, but as far as I can tell from the age of my Desktop,
the PCIe in it is ver. 1.1, and that card is working. And what is more
important, it gives a very substantial speed increase over USB 2.0 with
the same external HDDs.
You are right, the lane bandwidth in PCIe pre-v.2.0 is 2Gbit/s (250 MB/s),
which is less than the theoretical maximum rate of USB 3.0, but
I am yet to see any of the external USB 3.0 HDD to utilize the full
bandwidth of the USB 3.0.
I don't remember the numbers, - but in my configuration (that seems like
what you might have), I was getting sustained rates in the vicinity of 100
MB/s (definitely above 80 MB/s), while I was happy if I'd get over 20 MB/s
[sustained!] with USB 2.0 with the same drives.
So, for the price of $13, it was worth it, don't you think? ;-)
As I mentioned earlier, another limitation for PCIe x1 is the power.
It only matters for the USB-powered HDDs. I don't remember numbers
right now, but it is sufficient for at least one or even two USB drives.
At least my USB-powered drives work just fine.
And BTW, - about a month ago, I bought this USB 3.0 card reader (Yet
another $13):
http://www.amazon.com/Transcend-Super-Multi-Card-Reader-TS-RDF8K/dp/B0056TYRMW/
Copying files from the SD cards speeded up 3-10 times, depending on the
card.
Actually, im my testing, the sustained rate went 50-100% up even
if this reader is used with a USB 2.0 port, as my highest sustained rate
with USB 2.0 reader was at about 13-15 MB/s, and with this reader
and USB 2.0 port, it is around 20 MB/s. With a USB-3.0, I am getting the
sustained rate of 32-33 MB/s on my laptop, where, I suspect it might be
limited by its USB 3.0 card.
Mark, sorry for pushing on you some spending ideas. ;-)
... but at least they aren't as costly as any of the lenses... ;-)
Cheers,
Igor
Mark C Wed, 29 Oct 2014 07:14:51 -0700 wrote:
Thanks, Igor - I looked into adding a USB 3 card and found that the only
available slots on my PC are PCIe x1 - which I think is too slow to
support USB 3.0. Maybe I don't understand the specifications correctly - I
think PCIe 2.0 is needed.
Mark
On 10/28/2014 10:38 PM, Igor PDML-StR wrote:
Mark,
Just in case, - since you mentioned you were considering a USB 3.0
card, - Two years ago, I bought this card:
http://www.bhphotovideo.com/c/product/696114-REG/Transcend_TS_PDU3_2_Port_USB_3_0_PCI.html
I put it into my desktop that was put into "production" back in January of
2007. I am not using this desktop as frequently as my laptop, but I have
some software on it that is not available elsewhere, and so, it is very
nice to be able to use the same HDDs efficiently.
I don't remember if you are using a Mac or PC, but if it is a PC, $13
is not that much to get a much better experience.
Cheers,
Igor
PS. There are more expensive cards with that have more than 2 ports,
but those are (1) more expensive, and (2) they have some additional
limitations due to the PCI-e. However, if you've got an empty PCI-e x4 (or
x16) slot, I suspect you can buy something that is even better. Also, note
that the card referenced above may not adequate power to power some
"mobile" HDDs that are USB 3.0-powered (and require 0.9V). For those, you
need a card with an additional power connector (from the power source or
elsewhere). If you have any questions on this, - feel free to ask me.
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