Re: problems with front USB ports

In article <edbr15$55h$1@xxxxxxxxxxxxxxxxxxxxxxxxxx>, "Aussie"
<fuckU@xxxxxxxxxxxxxx> wrote:

"Brian Campbell" <aa356@xxxxxxxxxxxxxx> wrote in message
news:edbagb$4e2$1@xxxxxxxxxxxxxxxxxxxxxxxx
There is absolutely nothing wrong with the case. It is the hard drive.
It is sucking too much power that the USB port cannot handle.

What a load of bull***.

Just check your connectors to start with.Dont take these ***-heads
seriously.
Also ,make sure all of your USB/motherboard ports are enabled in the BIOS..

Unfortunately, they are correct. If you check the specs for
2.5" drives, the spinup current for the drive is 5V @ 1A. The
2.5" USB enclosures come with a special cable, with two USB
connectors on one end. One cable has the full four USB signals
(two data, +5, GND). The second connector is just for +5 and
GND. By combining two connectors, the idea is the drive can
get two times the 500mA limit for a USB port.

When I checked 2.5" USB enclosures on Newegg a while back,
this seemed to be a very common (and stupid) way to run
2.5" drives. Operating near the limits of the USB ports
is bound to uncover cases where the limit is exceeded or
there is too much voltage drop in the cabling and the like.
But I didn't manage to find a 2.5" that came with an adapter
and an aux power plug on the enclosure, as having a way
to add power to the drive, would avoid any issues.

When Asus sets up USB ports, a 2x5 USB header has two ports
on it. Power is fed to the 2x5 USB header from a common point.
On some motherboards, there is a jumper that allows selection
of either +5V or +5VSB. There is also a Polyfuse in the path,
that protects against drawing too much current - the Polyfuse
is rated to provide enough current for two ports plus a little
bit. For the 2.5" enclosure, the drive is not being used to
"wake" the computer, so +5V should be selected as the power
source. The +5V is the best one to use, as the power supply can
provide 25A or so on an output like that. On +5VSB, many power
supplies only have 2A or so. (On the M2NPV, there are USBPWxx
headers, so you can select +5V to run the front port.)

The fun begins, on those motherboards that have fixed all the
headers to run from +5VSB. The A8N family was one of the first
to dispense with the +5V/+5VSB selection jumpers, and I believe
they chose to run the headers from +5VSB. If you had a couple
2.5" enclosures connected to such a motherboard, the action of
accessing the hard drive in the enclosure, might even manage
to shut the computer down, when the +5VSB drops out.

In general, I'm not too impressed with the design of the 2.5"
enclosures. I'm still waiting to see one that is designed
properly, with its own power option for situations like this
(where the drive is not happy with the power it is getting).

There are some Firewire hard drive enclosures for 3.5" drives,
that have an interesting solution for this problem. Some
Firewire enclosures "store up" power until they have enough
to do the hard drive spinup. A 3.5" drive can draw up to
2.5 amps starting current, and not all computer Firewire ports
have that kind of current to offer. Once the drive finished
spinup (~10 seconds), the motor current drops to 0.6A to keep
the drive spinning, and 0.6A is within the limits of the
Firewire port. But nobody seems to use the same trick
for the 2.5" USB enclosures. Instead, they like the "two headed"
USB cable, as their powering solution.

Paul



USB ports,
by spec can only pump out 500 ma. Most hard drives consume more than
that. My guess is that the reason it works on the back and not the front
is that the hard drive is on the cusp, and there is just enough voltage
drop in the front ports to not be able to provide enough juice. Only
thing I can think of is to make a cable that takes the 5v and gnd directly
from a power cable and use that instead of the USB.

Venom (Venom@xxxxxxxxxxxxx) wrote:

: "nospam" <nospam@xxxxxxxxxxx> wrote in message
: news:44f8fb0d$0$22364$afc38c87@xxxxxxxxxxxxxxxxxxxxxxx
: > Hello,
: >
: > I have an Asus M2NPV-VM motherboard:
: >
: >
http://www.asus.com/products4.aspx?l1=3&l2=101&l3=0&model=1138&modelmenu=1
: >
: > I have installed 2 X 1gig sticks of DDR2 ram and an AMD 2X 3800 CPU
plus 1
: X
: > DVDRW drive and 1 X 320gig WD SATA2 drive. I am using the onboard
video
: and
: > sound as well as have all the USB and Firewire ports enabled. I do
not
: have
: > anyother devices in the machine. The machine also has a 500w PSU.
: >
: > My problem is with the front USB ports on my case. When I run a
memory
: > stick from them there are no problems, however, when I try and connect
a
: > 120gig Samsung 2.5" drive in an unpowered external case, the speed of
file
: > transfers drop to almost zero. (definately not USB2 speeds).
Thinking
: > that it may be a power problem, I plugged this external drive into the
: > motherboard's rear USB ports and it runs at the expected USB2 speed
: without
: > a hitch. I have checked to ensure that the PC case's front USB port
: > connectors are correctly plugged into the motherboard's internal USB2
: > connectors.
: >
: > Is there anything I can do to fix the front USB ports??
: >
: > Thanks,
: > Shane
: >
: >
: You are right. You don't have enough juice to run it in the front port.
: The cable for the case should have a Y connecter on it and you are
supposed
: to plug both ends into the USB ports and the other end into the case.
This
: is the drama you have when you buy a cheap arse case. You should have
bought
: a quality one with it's own power supply. Those hard drives require 1
amp to
: run them. USB only supplies a half an amp per port. You work it out.


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