usb conflict

Emachines Emachines t3958 intel celeron...
February 5, 2010 at 02:15:45
Specs: Microsoft Windows XP Professional, 2.933 GHz / 1014 MB
Hey people i new to this site and hoping to gain insight from problem is i recently bought an WD eternal HD,to back up all my music and pics pretty much to make as much space as possible in my HD,i wanted to make it the home of my itunes library as well however after moving all my files i found that even though they ipod and the WD HD work individually they wont when they are both plugged in at the same time,it gives me a "delayed cannot copy files at this time"error after doing research i found that they may be using too much power to both be able to run at the same time.can i resolve this issue by upgrading my power supply?i think its only like 250w.or is an external powered hub my only option without disabling the enhanced usb 2.0 host.or dumbing down my usbs...if it can be resolved by getting a new power supply what would you guys recommend? thanks in advance...

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February 5, 2010 at 05:04:24
No need to get a new Power Supply, just for doing what you're doing. Go to and look for an ac powered usb hub. I use one and they work great.

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February 5, 2010 at 06:42:37
I wouldn't recommend that you have only one copy of any files you want to keep. If you are going to keep the files on an external drive then make a second copy somewhere else. The usual method is to keep the first copy on the computer and then a backup copy on an external. you could also burn files to DC/DVD.

Keeping only one copy of important files is risky business.

Add a second hard drive to the computer internally for extra space.

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February 5, 2010 at 13:32:27
thanks i appreciate the imput,I'll probably burn a second copy to a cd or dvd,I'll also look into getting an ac powered hub.But would upgrading the power supply also resolve the usb conflict,the hard drive has a ac power supply,so my guess would be to use the powered usb for my ipod right?

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February 5, 2010 at 14:12:09
The problem is that each USB controller can only supply a certain amount of current This has nothing to do with your PSU. It is a limitation of the USB specs.

Your only other solution is to try connecting to a different controller that is either not in use or is powering a low current drain piece of hardware.

USB controllers generally support 2 USB ports. If ports are physically side by side then they may be using the same controller. Connect a low power device like a keyboard or mouse to the other.

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February 5, 2010 at 15:13:49
ok so a new psu isn't the answear,one of my friends suggested that getting a new pci card could resolve this as it would be using a different path on the Mother board but i dont know if that would just result in the same problem with more usb's.First i'll try as you mentioned above ive done this but havent really tried all the usb combinations,if not then i'll get the external powered usb hub i dont have a problem with it,it's just that i'm trying to avoid having more things plugged in to the powerstrip and wires to manage...Thanks again for the help.i called WD they said it was a problem with iPod i called Apple they said its a problem with WD..So your help is really appreciated...its sad Apple,& WD dont want to help theyre consumers

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February 5, 2010 at 15:42:02
USB powered external hard drives are designed for use as portable devices. if you are using in one place a 3.5" 120VAC powered USB external hard drive is preferred. Then it wouldn't draw so much power from the USB port. As it is now it needs to pull power to actually rotate the hard drive as well a transmit data.

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February 5, 2010 at 19:38:09
My HD is rated ac120-240v it's plugged into a power strip,I
tried all combos of usb's to no avail as a last resort I'll get the
powered USB hub this will hopfully juice the iPod enough to
leave the HD unaffected,I've read other post where others
have had sucess with it,really I should get a up to date PC as
mine has been around a while. : )

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February 5, 2010 at 20:07:30
If your external drive is AC powered then the ipod may be the problem. The AC powered drive is only supposed to draw about 500mA with the port capable of 1500mA. Try the ipod with any other device and see if you still have the same problem.

Are you transferring files from the external to the ipod when they are both connected at the same time?

How many USB ports are on your computer? Do you also have an internal card reader?

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February 5, 2010 at 20:44:30
Actual conflicts between USB devices are quite rare. Usually the problem is they don't get along with ports that are not directly connected to the mboard, and/or they can't get enough current from the port they're plugged into, or there is an IRQ sharing problem.

USB devices may not work correctly when they're connected to certain USB ports e.g. ports in a hub or on the front of a desktop case. If you have a desktop computer, you may have an IRQ sharing problem you need to fix, or your power supply may be starting to fail.
See response 3 in this:

Also - if you are using a USB extension cable, some of them have inadequate wiring and will not work properly with some USB devices.

In addition, all external drives connected by USB require that the port (or ports) they connect to can actually supply 500ma of current.
They often don't work properly in a port in a multiple port hub that connects to one directly connected to the mboard USB port, or they work but only when they're the only thing plugged into the hub.

3.5" external drives are larger and always come with an external power adapter that plugs into the external case - that adapter must be plugged in and working because 3.5" drives plus their controller require a lot more than 500ma of current total. The hard drive requires both 12v and 5v.

2.5" external drives ("portable" or similar external drives) are smaller and usually don't come with an external power adapter that plugs into the external case. The hard drive and the external case only require 5v.

Recent 2.5" hard drives of any size draw up to close to but no more than 500ma of current while spinning up - the external drive enclosure's circuits don't draw much - so most will work fine when only one USB connection is made to the computer, if the USB port they plug into can actually supply 500ma (some laptop built in ports cannot; all the laptop PCMCIA and ExpressCard USB 2.0 controller cards I've looked at the specs of so far can only supply 500ma total for all the USB ports in them, unless the card has an 1/8" jack for connecting an external power adapter to and you connect one).

Older models of larger sizes of 2.5" hard drives draw more than 500ma - those must have two USB connections at the computer end, or if the case has a 1/8" jack, one USB connection and an external adapter can be used. Because of those older hard drives requiring more current, you often see that an external enclosure is not for xxxgb drives and above, but if it's a recent larger drive the external enclosure will handle it fine. If in doubt, look up the specs for an older model. or read it's label.

Some 2.5" external drives or enclosures come with a Y USB cable, or 2 cables, so you can connect to up to 2 USB ports on the computer end. Some have an additional 1/8" jack on the case you can plug an external power adpter into it if you need to.

If your 2.5" drive won't work when you connect only one USB connection to a computer and it has only one plug on each end, when it is connected to a port it should be able to get 500ma from that's directly connected to the mboard, if the case has no 1/8" jack for a power adpter, you need to get yourself a USB Y cable to suit.

If you get a 2.5" external enclosure or prepackaged external hard drive, I recommend you get one that has 2 cables or a USB Y cable, or that has one USB cable and a jack on the case for a power adapter.
E.g. Vantec - has a USB Y cable, one of the two plugs on the computer end is pass-through - you can connect other USB devices to it.

Similar applies to firewire connected drives.

eSATA connected drives don't have the current problem, that I know of.

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February 5, 2010 at 21:11:17
my pc has 5 usb ports and sd/mmc/ms/ms-pro & CF/microdrive the ipod didnt have problems while using other devices like blu tooth stick, usb card readers and printer,the HD is a WD my book essential 1tb,i read on the wd support site that power surges will cause it to drop off,i'm going to read the thread listed above and see irq is the culprit
thanks for the support

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February 5, 2010 at 21:12:30
forgot to mention theres only one usb in the front and two in the back high and two in the back low

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February 6, 2010 at 05:21:31
The card reader runs off USB. IRQs are not the issue. I explained what the problem is already. What happens when you use the front USB port for the ipod?

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February 6, 2010 at 11:18:00
The USB uses two IRQs per (all) the USB 2.0 controller(s) built into the mboard - one for backwards compatible USB 1.1 support, one for USB 2.0 support. If you install a USB 2.0 controller card in a slot, it may or may not use the same two IRQs, depending on whether the maker used the same chip/chipset that supports USB as on the mboard.
All devices you plug into USB ports use the USB port's IRQ.

However, sometimes on desktop computers you can have a situation where some other device is using (sharing) the same IRQ as the USB controller related devices. In that case, typically, the USB ports work fine with some devices, but they DO NOT work fine with other devices, especially likely if the USB device is more sophisticated.
See the first link in response 9 for more info about that.

Some maker's USB chips/chipsets have a reputation of working properly for/with more USB devices than others.
E.g. back before USB 2.0 controllers were available, the early Via ones worked properly with fewer devices than NEC ones did.
USB 1.x only controllers used either one of two USB standards - OHCI, or UHCI - some USB devices work fine with one standard but do NOT work with the other.
I haven't heard of that being as much of a problem with USB 2.0 chips/chipsets, but it's quite possible that still applies to a lesser extent with those.

USB hubs don't work for all USB devices.
How to add more directly connected USB ports.
How to t-shoot and possibly fix problems accessing data on an external drive or flash drive or memory card, etc., and what usually causes the problem.
External drive requirements.
See Response 4:

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February 6, 2010 at 14:42:09
ok after consideration i unplugged all my usb devices,reboot avoided using the front usb port,then plugged the HD in the back on the upper usb and the iPod on the lower usb and much to my amazment they both work without conflict,my iPod sucessfully synced,and the HD is hummin along.Dont know why the front usb does this or why i insist on trying to use it, it seems that its high priority or is connected to all ports ,thankyou for all the advice and putting up with my noobness even things that werent the issue gave me new understanding insight as how these things work you guys and this site rock.

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February 6, 2010 at 17:14:19
We're glad to hear you found a situation that works.

Your problems are very common. We get people posting about problems with USB devices not being recognized properly nearly every day.

I have one case that has inadequate lower front USB port wiring. They work fine with mice and keyboards, but not with flash drives, external drives, printers, an iPod Shuffle, a card reader, etc.
A friend has the same problem with a ~three year old cheap case .

If you're handy, if you replace the wiring to the lower front ports with adequate wiring, they'll work fine.


Unplug the cord to the case / PS, or switch off the AC to the case / PS otherwise.

E.g. get a USB cable that has obviously braided wire shielding that is rated for USB 2.0, chop off it's ends, pare back the braided sheath on each end to expose the individual wires, chop off the existing wiring at the mboard USB header so you have a short wire still there for connecting to each wire in the female connector(s), do the same on the USB ports end, or if you have a soldering iron, unsolder the wires from the USB ports, connect the replacement wire, solder the connections preferably, or twist the bare ends together, apply electical tape over the splice. Keep track of which wire goes where (the color of the insulation at each connection if you want to unsolder the wires there at the USB port end), or cut and connect one wire at a time.

For the ports higher up, there may be 4 or 5 wires to each individual USB port inside the case, which you can fix the same way, or only 4 or 5 wires for more than one USB port, in which case it's a hub and not everything works in a port in a hub - replacing the wires MIGHT help - or just leave the wiring alone.

You only need 4 wires. If there is a fifth wire, it's an extra ground wire that connects to the outside metal shell of the USB ports. You can just not connect that, or jumper the shell to the ground - probably black connection of the 4 others at the USB ports. On the mboard end, if it has5 wires, it doesn't matter which ground - probably black - wire you run to the USB ports.

The upper case front ports wiring may connect to (a) female connector(s) on pins on a USB header, or to a regular male USB plug that plugs into a (regular female) USB port inside the case, or outside the case at the back.
If it has a card reader in it too up higher in the same unit as the USB ports, it should have a separate cable from the card reader to a USB header or to a regular USB plug.
If there is only one cable to the USB ports and the card reader, then the USB port or ports is/are in a hub - not everything works in a port in a hub - replacing the wires MIGHT help - or just leave the wiring alone.

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