I'm fixing to upgrade my circa 2009 PC with a USB 3.0 card. Knowing that
there are many people here who understand this stuff better than I do -
a few off topic questions... (since the USB card will be used to support
drives that will store photos taken with my Pentax gear, it's not
completely off topic...)
It seems that you need at least a PCIe 2.0 slot with 5 GBps throughput
to get full USB 3.0 speed. My PC only has two free PCIe 2.0 x1 slots
@2.5 GBps each. The sole PCIe 2.0 x16 slot is occupied by the video
card. There are also a couple free legacy PCI slots - I think they are
32 bit PCI slots. (The mother board manual simply calls them "PCI slots").
Adding a USB 3.0 card to one of the free PCIe x1 slots seems to be the
obvious route to go. With PCIe x1 I will only get 50% of the possible
maximum throughput. Based on what I read - that will still be a good bit
faster than USB 2.0... If USB 3.0 is theoretically 10x faster than USB
2.0, then my theoretical increase will be 5x.... is that right?
Would there be any point in even considering adding a USB 3.0 card to a
legacy PCI slot? As best I can tell PCI has a maximum of 133MB/s or
roughly 1 GBps so USB 3.0 on a PCI bus could be about twice as fast as
USB 2.0??? I assume far short of the increase expected from using a PCIe
x1 slot...
As I understand it, each USB controller splits the bandwidth between all
active devices connected to it. So if I am copying files between two USB
drives hooked up to a single USB controller the bandwidth would be split
between them. That makes me wonder - if I add two USB 3.0 cards to my
PC - one in each of the free PCIe x1 slots - and put one drive on each
card, will that result in each controller running at full speed when
copying from drive to drive? That would be as fast as copying between
two drives on a single controller running off a full speed PCIe 2.0
slot. Is my thinking right on that point? Since the USB cards are
about $20 each, I'd give that a try if it would speed things up.
Lastly - is there anything in particular - e.g. desirable chip sets or
features or brands to avoid - in USB cards and hubs? (I plan to add at
least one card and one external hub.)
Thanks!
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