usb 3.0 card

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Andy

What factor of my system is necessary to be able to use the full speed of a USB 3.0 card ?

Thanks.
 
Andy said:
What factor of my system is necessary to be able to use the full speed of a USB 3.0 card ?

Thanks.
Click to expand...

USB3 can be provided two ways. It can be
provided by the main chipset (some Intel chipsets,
chipsets like AMD A75 - Wikipedia can give you a list).

Or, for the majority of people, USB3 comes from
a standalone chip made by NEC, Etron, Asmedia, and so on.

With those chips, there is a tendency to put a PCI
Express single lane interface. That's PCI Express x1.
Doing so, saves pins on the chip, and reduces chip cost.
That's how you can sell a $25 USB3 PCI Express card.

Motherboards have several kinds of PCI Express slots,
but we'll concentrate on the PCI Express x1 ones.

PCI Express Rev 1.1, x1 lane = 250MB/sec
PCI Express Rev 2.0, x1 lane = 500MB/sec

The second of those, does a better job of exposing
all of the USB3 capability. For example, if you
bought a BlackMagic video capture device with USB3
connector, the software for that device actually
tests and verifies that a 500MB/sec lane is present.

There are no other devices I'm aware of, where bandwidth
testing is involved.

So the ideal situations, from best to worst.

1) Chipset USB3 port, with no restriction on the bus
connection to the rest of the chipset. The DMI bus or
Hypertransport bus connection to the Southbridge in
such a case, likely runs 2GB/sec or higher, plenty for
a USB3 stream. You don't have to worry about the
connection being choked off. And as for implementation,
I think the AMD A75 and similar, they didn't design the
USB3 logic block themselves, but bought a design (intellectual
property) from a company making a successful chip.
That means less development cost, to ship a design.

2) Plug an add-in card into a Rev 2.0 slot. You can use
a video card slot for this, if one is available. Some
motherboards have multiple video card slots. You can
plug an x1 card, into an x16 slot. It's a waste, but,
you're getting the best. Video card slots tend to support
Revision 2 or even Revision 3, for the very highest rate
of transfer. No USB3 chip I've heard of, uses PCI Express
Revision 3.

3) Plug an add-in card into a Rev 1.1 slot. This is good
enough for enclosures where the disk enclosure USB3 adapter
chip is limited to 200MB/sec anyway. Such an enclosure,
even if you stuffed a high performance SATA SSD into
the enclosure, it would be the enclosure chip which was
the limiting factor. So in that situation, the low
end and quite common PCI Express x1 slot is good enough.

There is more to PCI Express bandwidth than just the "plumbing
rating". When I quote 250MB/sec, that's raw bitrate on the
lane. The typical chipset has rather small buffers fitted
at the end of the link, and the buffer size can actually
cut the transfer rate in half. You shouldn't assume that
the number printed in the Wikipedia article for PCI Express,
is the final story.

http://www.plxtech.com/files/pdf/technical/expresslane/Choosing_PCIe_Packet_Payload_Size.pdf

The figure on page 2 there, shows the "efficiency" number.
You multiply the 250MB/sec number by the "efficiency", to
get a better value (trending in the right direction) for
what your x1 lane can actually do. Is it easy to find
out the buffer size of your chipset buffer ? Nope. It's
a trade secret. It would be embarrassing, if everyone
knew their 4GB/sec video card slot, wasn't actually
doing 4GB/sec. The horror.

The UAS protocol here, has a calculated transfer rate
of 336MB/sec. But no device to date has achieved that.
At least for USB storage. Keep your eyes peeled though,
for benchmarks, because some year, they'll fix that.
The last time I checked, the best seemed to be around
200MB/sec or so.

http://www.nordichardware.com/Archive/LucidPort-announce-USB-3.0-to-SATA-bridge-chip.html

Plug your new USB3 card into a video card slot... and, enjoy.

It's a good thing the last motherboard I bought, has two
video card slots.

Paul
 
USB3 can be provided two ways. It can be

provided by the main chipset (some Intel chipsets,

chipsets like AMD A75 - Wikipedia can give you a list).



Or, for the majority of people, USB3 comes from

a standalone chip made by NEC, Etron, Asmedia, and so on.



With those chips, there is a tendency to put a PCI

Express single lane interface. That's PCI Express x1.

Doing so, saves pins on the chip, and reduces chip cost.

That's how you can sell a $25 USB3 PCI Express card.



Motherboards have several kinds of PCI Express slots,

but we'll concentrate on the PCI Express x1 ones.



PCI Express Rev 1.1, x1 lane = 250MB/sec

PCI Express Rev 2.0, x1 lane = 500MB/sec



The second of those, does a better job of exposing

all of the USB3 capability. For example, if you

bought a BlackMagic video capture device with USB3

connector, the software for that device actually

tests and verifies that a 500MB/sec lane is present.



There are no other devices I'm aware of, where bandwidth

testing is involved.



So the ideal situations, from best to worst.



1) Chipset USB3 port, with no restriction on the bus

connection to the rest of the chipset. The DMI bus or

Hypertransport bus connection to the Southbridge in

such a case, likely runs 2GB/sec or higher, plenty for

a USB3 stream. You don't have to worry about the

connection being choked off. And as for implementation,

I think the AMD A75 and similar, they didn't design the

USB3 logic block themselves, but bought a design (intellectual

property) from a company making a successful chip.

That means less development cost, to ship a design.



2) Plug an add-in card into a Rev 2.0 slot. You can use

a video card slot for this, if one is available. Some

motherboards have multiple video card slots. You can

plug an x1 card, into an x16 slot. It's a waste, but,

you're getting the best. Video card slots tend to support

Revision 2 or even Revision 3, for the very highest rate

of transfer. No USB3 chip I've heard of, uses PCI Express

Revision 3.



3) Plug an add-in card into a Rev 1.1 slot. This is good

enough for enclosures where the disk enclosure USB3 adapter

chip is limited to 200MB/sec anyway. Such an enclosure,

even if you stuffed a high performance SATA SSD into

the enclosure, it would be the enclosure chip which was

the limiting factor. So in that situation, the low

end and quite common PCI Express x1 slot is good enough.



There is more to PCI Express bandwidth than just the "plumbing

rating". When I quote 250MB/sec, that's raw bitrate on the

lane. The typical chipset has rather small buffers fitted

at the end of the link, and the buffer size can actually

cut the transfer rate in half. You shouldn't assume that

the number printed in the Wikipedia article for PCI Express,

is the final story.



http://www.plxtech.com/files/pdf/technical/expresslane/Choosing_PCIe_Packet_Payload_Size.pdf



The figure on page 2 there, shows the "efficiency" number.

You multiply the 250MB/sec number by the "efficiency", to

get a better value (trending in the right direction) for

what your x1 lane can actually do. Is it easy to find

out the buffer size of your chipset buffer ? Nope. It's

a trade secret. It would be embarrassing, if everyone

knew their 4GB/sec video card slot, wasn't actually

doing 4GB/sec. The horror.



The UAS protocol here, has a calculated transfer rate

of 336MB/sec. But no device to date has achieved that.

At least for USB storage. Keep your eyes peeled though,

for benchmarks, because some year, they'll fix that.

The last time I checked, the best seemed to be around

200MB/sec or so.



http://www.nordichardware.com/Archive/LucidPort-announce-USB-3.0-to-SATA-bridge-chip.html



Plug your new USB3 card into a video card slot... and, enjoy.



It's a good thing the last motherboard I bought, has two

video card slots.



Paul
Click to expand...

Thanks.

I have one PCI Express slot.

Could I use that ?

I am happy using the on board video, it only uses 128 Mb and I plan to up my RAM to 4 Gbs.
 
Andy said:
Thanks.

I have one PCI Express slot.

Could I use that ?

I am happy using the on board video, it only uses 128 Mb and I plan to up my RAM to 4 Gbs.
Click to expand...

It's your choice as to what slot you use. The lack of USB3
peripherals that "need the speed", suggests to me that using
the best slot isn't a priority. If you have the BlackMagic
USB3 video capture box, then yes, you'd probably want to
use the best slot available. Or, buy a motherboard that has
native USB3, and not the add-on USB3 type.

Paul
 
It's your choice as to what slot you use. The lack of USB3

peripherals that "need the speed", suggests to me that using

the best slot isn't a priority. If you have the BlackMagic

USB3 video capture box, then yes, you'd probably want to

use the best slot available. Or, buy a motherboard that has

native USB3, and not the add-on USB3 type.



Paul
Click to expand...

I have a USB 3 external hard drive.

I could use the extra speed for image backups.

Canon camera may also benefit.

Andy
 
Andy said:
I have a USB 3 external hard drive.

I could use the extra speed for image backups.

Canon camera may also benefit.

Andy
Click to expand...

Let's say, for the sake of argument, you plug the
USB3 card into "any old slot" and you get 187MB/sec
transfer rate.

The fastest hard drive available today for SATA,
is around 180MB/sec. Many other hard drives sustain
around 135MB/sec. Those would fit within a 187MB/sec
limitation.

If you had a Revision 2 slot with 500MB/sec lanes,
then eventually the USB3 transfer protocols become the limiting
factor. Just like on USB2 (60MB/sec), the best you
could do was around 35MB/sec. That was a polled protocol
limitation of some sort.

Paul
 
And those extraneous/obnoxious blank lines are a characteristic

dysfunction of GGs and their clueless users. I just add the posters

to my KF.
Click to expand...

Thanks, I appreciate your kindness in not bumming me out with your "negative waves."
 
Andy wrote:







Let's say, for the sake of argument, you plug the

USB3 card into "any old slot" and you get 187MB/sec

transfer rate.



The fastest hard drive available today for SATA,

is around 180MB/sec. Many other hard drives sustain

around 135MB/sec. Those would fit within a 187MB/sec

limitation.



If you had a Revision 2 slot with 500MB/sec lanes,

then eventually the USB3 transfer protocols become the limiting

factor. Just like on USB2 (60MB/sec), the best you

could do was around 35MB/sec. That was a polled protocol

limitation of some sort.



Paul
Click to expand...

This is what I have.

PCI Express Rev 2.0, x1 lane = 500MB/sec


Your previous post made no mention of transfer protocols.

??

Andy
 
Andy said:
This is what I have.

PCI Express Rev 2.0, x1 lane = 500MB/sec


Your previous post made no mention of transfer protocols.

??

Andy
Click to expand...

Scroll down to the table. The newer UAS protocol
can do 336MB/sec to a storage device. Which
would take more than an add-on chip and a
250MB/sec single lane could handle.

http://www.nordichardware.com/Archive/LucidPort-announce-USB-3.0-to-SATA-bridge-chip.html

At the current time, the fastest enclosure I've heard
of, is 200MB/sec. I haven't been scouring the
Internet for newer benchmarks, so by now there could be
a better chip for the job. But if nothing has changed,
you're not going to tax that 336MB/sec limit in
the table on the Nordic Hardware page. You would
need a better USB3 peripheral chip, as well as a
good SSD, to test for the 336MB/sec limit. No hard
drive is going to make such a test easy. (It might
require one of those USB3 chips that does RAID0
disks.)

Paul
 
Andy wrote:







Scroll down to the table. The newer UAS protocol

can do 336MB/sec to a storage device. Which

would take more than an add-on chip and a

250MB/sec single lane could handle.



http://www.nordichardware.com/Archive/LucidPort-announce-USB-3.0-to-SATA-bridge-chip.html



At the current time, the fastest enclosure I've heard

of, is 200MB/sec. I haven't been scouring the

Internet for newer benchmarks, so by now there could be

a better chip for the job. But if nothing has changed,

you're not going to tax that 336MB/sec limit in

the table on the Nordic Hardware page. You would

need a better USB3 peripheral chip, as well as a

good SSD, to test for the 336MB/sec limit. No hard

drive is going to make such a test easy. (It might

require one of those USB3 chips that does RAID0

disks.)



Paul
Click to expand...

I think what you are saying is that you are not sure that there will be any speed increase ?

Okey dokey.


Andy
 
Andy said:
I think what you are saying is that you are not sure that there will be any speed increase ?

Okey dokey.


Andy
Click to expand...

The last time I looked, the fastest USB3 enclosure
I could find was 200MB/sec.

You have to read a *lot* of posts and threads, to
find this information manually. That's why I'm not
doing this on a continuous basis.

Paul
 
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