USB 2.0 PCI Extension Card

  • Thread starter Thread starter Christo
  • Start date Start date
C

Christo

If i stick a USB card in one of my PCI slots

will it run slower than its capable of? It wont run the USB devices
connected to it at maximum speed will it? If not then whats the difference?
is it a noticeable difference? I am going to be suing it for multiple
external hard drives, Is it reccomended?

Same for firewire do they operate at the 400Mb/s they are meant to?

Thanks

Christo
 
If i stick a USB card in one of my PCI slots

will it run slower than its capable of?
No.


It wont run the USB devices
connected to it at maximum speed will it?
Click to expand...

Yes it will
If not then whats the difference?
Click to expand...
Invalid question.
is it a noticeable difference?
Click to expand...
As above
I am going to be suing it for multiple
external hard drives, Is it reccomended?
Click to expand...

Dunno but my guess is it will work well :)
Same for firewire do they operate at the 400Mb/s they are meant to?
Click to expand...
They may well do,other parts of the system may not.
Thanks
Click to expand...
You are welcome :)
Christo
Click to expand...
Me :)




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Christo said:
If i stick a USB card in one of my PCI slots

will it run slower than its capable of? It wont run the USB devices
connected to it at maximum speed will it? If not then whats the
difference? is it a noticeable difference? I am going to be suing it for
multiple external hard drives, Is it reccomended?

Same for firewire do they operate at the 400Mb/s they are meant to?
Click to expand...

I think you're assuming PCI is slower than USB or firewire but it is not.
PCI is 33Mhz by 32 bits which is over 1Gbit/sec so should be able to run usb
ok at 480 or firewire at 400. Of course in reality nothing achieves it
stated speed usually because something else, say hdd access, is slowing it
down.

Michael
 
If i stick a USB card in one of my PCI slots

will it run slower than its capable of? It wont run the USB devices
connected to it at maximum speed will it? If not then whats the difference?
is it a noticeable difference? I am going to be suing it for multiple
external hard drives, Is it reccomended?

Same for firewire do they operate at the 400Mb/s they are meant to?

Thanks

Christo
Click to expand...

Shep answered the questions pretty well, I"ll only add that
firewire is typically faster than USB2 for hard drive use,
if you don't have the external enclosures yet you might
consider getting one with both interface types and a
firewire card instead.

Otherwise, a USB card will do exactly what you expect of it.
NEC chipset based cards are typically as fast or faster than
other alternatives, are among the safest choice in cards.
 
Michael C said:
I think you're assuming PCI is slower than USB or firewire but it is not.
PCI is 33Mhz by 32 bits which is over 1Gbit/sec so should be able to run
usb ok at 480 or firewire at 400. Of course in reality nothing achieves it
stated speed usually because something else, say hdd access, is slowing it
down.

Michael
Click to expand...

if i was going to run 4 USB hard drives from the same PCI card

thats 480*4=1920

nearly 2Gb/s

would this not slow down the rest of the PCI bus? and eat up bandwidth and
mean the hard drives might not run at capable speeds?

TIA

Christo
 
Christo said:
if i was going to run 4 USB hard drives from the same PCI card

thats 480*4=1920

nearly 2Gb/s

would this not slow down the rest of the PCI bus? and eat up bandwidth and
mean the hard drives might not run at capable speeds?

TIA

Christo
Click to expand...

Yes. Yes.
 
if i was going to run 4 USB hard drives from the same PCI card

thats 480*4=1920
Click to expand...

Not really, you will never see even remotely close to 480,
and to clarify, that's 480 megaBITS, not bytes.

Real-world rates per drive are closer to 25MB/s.
Some benches make that appear higher due to caching, but
that's not actual PCI bus traffic.

nearly 2Gb/s
Click to expand...

Nope, and aonther issue is that you can only get the
throughput that the interface allows, at least each pair of
ports have shared bandwidth, so in practice you might find a
limit closer to 2 x 25MB = 50MB/s

would this not slow down the rest of the PCI bus? and eat up bandwidth and
mean the hard drives might not run at capable speeds?
Click to expand...


Any PCI card moving dozen(s) of MB of traffic will indeed
slow the PCI bus, if it needs more than it's share of bus
time to get the data transferred. It's more of an issue if
you have other traffic-heavy PCI devices... some people do,
others don't. Most do have at least a sound card, and some
have Gigabit NIC. Those two devices and heavy use of the
PCI USB card could require teaking PCI latency for maximal
performance- but still aiming only for proper function of
each device, that 25MB/s per drive.

So yes, it most definitely means your drives will not be
even remotely close to their max capable speeds (as seen on
their native SATA or PATA bus). External USB is of benefit
for it's external and removable nature, it's the slowest way
possible to run a semi-modern drive on a semi-modern system.
Remaining question is whether you actually need higher
throughput, compromises have to be made somewhere.
 
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