I have an HP Pavilion DV8000 laptop running Win XP SP2. It has a max power
supply of 500mA to each USB port. However I have been looking at Western
Digital external USB HDDs which state that 500mA is not enough and that over
600 is required.

What controls this power supply, is it Windows, can it be increased safely
and if so how?

Thanks in advance.

Sorry I should have added this; This is the URL to the Western Digital page
that details this:
http://wdc.custhelp.com/cgi-bin/wdc....ted=1165616390

In summary:
"If you are using a WD Passport 2.5" hard drive, please ensure that the
computer's USB ports supply at least 650 milliamps through the USB ports. If
your USB controller or USB hub is limited to 500 milliamps of power draw, you
may need to use a USB 2.0 Power Booster Cable or a WD Passport Power Supply."

Is this really correct, I thought every computer was limited this way!?

Thanks again

Its not uncommon for USB devices to have a seperate power supply when the
device power requirements dictate such
And I dont believe you can up the usb power output

"A Taxed Mind" <ATaxedMind@discussions.microsoft.com> wrote in message
news:9945BA88-DAE9-4862-9860-4D3F962D5D62@microsoft.com...

You will need to find a USB Hub or USB PCI card that can meet your power
needs.
However the WD Passport Power Supply looks like the least expensive way to
go
and with it the USB drive can easily be used on multiple computers.

JS

"A Taxed Mind" <ATaxedMind@discussions.microsoft.com> wrote in message
news:9945BA88-DAE9-4862-9860-4D3F962D5D62@microsoft.com...

"Taxed Mind" <TaxedMind@discussions.microsoft.com> wrote in message
news:69310D39-F463-468F-B89A-35123A3CBC9C@microsoft.com...
And that's entirely standard. The OS doesn't matter; this is a hardware
specification.

You generally can't run a hard disk, including laptop hard disks, from one
USB port. This is why USB desktop drive cases come with a power supply,
and why USB laptop drive cases come with a 2-headed USB cable. One of the
heads draws the extra power required from the other port.

No, it's the circuit design.

No. Use external power supplies or the dual-head cable.

HTH
-pk

"Taxed Mind" <TaxedMind@discussions.microsoft.com> wrote in message
news:69310D39-F463-468F-B89A-35123A3CBC9C@microsoft.com...
Look for a " 2-headed USB cable", a USB cable that will have two plugs that
can each go into one of the USB ports on your laptop. The other end plugs
into the hard drive. But I wouldn't do this unless you're planning to carry
the external drive with you when you take the laptop on a trip. I use an
external drive which has its own power supply and AC adapter, and it's fine
except when I want to move it.

Good luck, Dan S

I have used about 6 different WD Passport 2.5" drives (80-160GB) - they
have all worked off of a single USB port on a couple of different desktop
machines and at least 3 different brand laptops. On one other laptop
(older), I needed an external power supply - used one from an old USB 1.1
hub.
Try it first - if it doesn't spin up reliably (that is the critical part,
as usually once they spin up the power requirement goes down), you may
need a cable to connect a second USB port to the drive (only used for
power, not data), or an external power supply.

"JS" <@> wrote in news:usFJykDRIHA.2396@TK2MSFTNGP02.phx.gbl:

"Taxed Mind" <TaxedMind@discussions.microsoft.com> wrote in message
news:69310D39-F463-468F-B89A-35123A3CBC9C@microsoft.com...
500 mA is a limitation of the USB port hardware. Nothing to do with XP.

Something drawing that much power on a laptop battery, smart?
Dave

"he" <who@dat.dere> wrote in message
news:Xns9A0DD7A7981471h6y23@207.46.248.16...

Taxed Mind:
Our experience with 2 1/2" USB external HDDs parallels that of "he". While
it is true that many, if not most, of these 2 1/2" external HDDs will draw
current greater than the 500 mA specified for a USB 2.0 port, we have found
that in the majority of cases the 2 1/2" USBEHDs will work reliably
connected to a single USB port even without an external power supply.

But as "he" also points out. Not always. There *will* be cases where one
would need an external PS for the device or the USB dual-head cable (so as
to connect the device to two USB ports) similar to the WD "Power Booster
Cable" you referred to in order for the device to properly function.

So if you're set about using such a device but aren't interested in the
add'l expense, and even annoyance, of purchasing either an external PS or
the dual-head cable, then I would suggest you purchase the WD Passport
device locally with the understanding from your local dealer that you will
have return privileges should the device not properly operate with your
machine without having to purchase those accessories.

Other than that, simply consider a "normal" 3 1/2" USBEHD device which
includes its own PS.
Anna

Thanks very much for your help guys. Best wishes over the festive break.