~misfit~ wrote:
On 18/07/2019 11:16 AM, Paul wrote:

For example, for a long time, add-on USB3
was always a hair short of "full performance".
There is one chip out today, with a PCI Express
x2 interface, that improves on the older PCI3
x1 cards, and finally, it is able to match
Southbridge USB3.

What chip is that Paul? I've been very disappointed with the various
USB3 expansion cards I've tried. While my PC doesn't have a PCIe x2 (or
a PCIe x4) slot it does have a spare PCIe gen3 x16. (It has native USB3
but you can never have too many fast USB ports for external HDDs.)

Cheers.

What's important here is the chip, not the brand.

https://www.startech.com/ca/Cards-Ad...rd~PEXUSB312A2

Chipset ID ASMedia - ASM2142

And you're buying this for performant USB3.0 (as in 500MB/sec),
as it would likely clip a little off USB3.1 rev2 operation.

By picking a card which attempts to operate at "one higher
standards version", it gives better performance on the
*previous* standards version. If you get my drift.

The chip has a 2 lane interface (2 lanes of a PCI Express x4
minimum). You should be able to plug that into a PCI Express
x16 slot (what I would likely be doing in practice).

On PCIe Rev1.1 = 2*250MB/sec = 500MB/sec = "cramped"

On PCIe Rev2 = 2*500MB/sec = 1000MB/sec = "good enough for USB3.0"
(PCI Express always has overhead and can't actually
run at the full rate)

The chip is Rev3 capable, but not everyone will have
a slot with that on it. 2x1000MB/sec would be sufficient to
give a good shot at USB3.1 Rev2 1000MB/sec operation on one
port.

http://www.asmedia.com.tw/eng/e_show...x=175&item=178

I bought the thing assuming a Rev2 slot would be available, like
on my Typing Machine.

On the Asmedia page, there is now an ASM3142, but I don't
see what is significant on that chip versus 2142.

Paul