Hi,

I've got a strange usb problem and thought somebody here might be able to help me out after some unsuccessful Googling.

My problem is that the front usb ports on my case only work with some usb devices. I can plug a flash drive in, or my printer but my passport drive won't work. I think I've decided that anything with its own power works fine, but those things that take power from the usb port don't work.

Now, I thought, 'oh that's just my front usb ports' and wasn't too worried. It's alright for them to go wrong, they often do and are easy to replace but then I bought myself a usb hub to plug into my back ports, thinking that would sort out my problems. It didn't. The things that didn't work in the front also don't work in the hub.

When I plug my passport drive in, or mp3 player or anything similar I get a "clunk clunk" of response from windows and the 'found new hardware' dialogue appears. It tells me it's found an unknown device and would I like it to look for drivers or would I like to help it- the way it usually does when you plug in something that needs drivers. I don't have time to respond to it though as I get a "clunk clunk" to say the device has been unplugged. 'Found new Hardware' tells me the device has been unplugged as well. It hasn't. While the device is plugged in this goes round and round.

I assumed this was to do with my usb drivers so I uninstalled and installed them and had no luck. Was it a problem with my operating system? I reinstalled that too. The problem is still there. Has anyone got any ideas about what to do? I'm concerned that the problem is with my motherboard and I really don't want that. Is there anything I can do...?

Thanks in advance!

Is this a store bought PC? How old?

To me, it sounds like your PC has a terrible, low output power supply.

I normally see this problem in laptops or ten-year-old PC's. The problem is your PC doesn't have enough power to power high-consumption USB devices.

Also, do you have the external DC adapter for your passport drive? That's the easy way to get it to work. Although I think they don't supply that with the product...

The best option is to replace your power supply. Generally you want either a mATX or an ATX power supply. Generally, if you have a large tower case then its an ATX power supply and if you have a slightly smaller, slimmer desktop case its a mATX power supply.

If your PC has a manufacturer and model number, you or I can lookup the information and find out what power supply is needed.

Now, if your PC is top of the range and/or relatively new then this doesn't apply but I think I'm on the right track. If this were a motherboard or USB port issue (as in dead USB ports) then I would expect no devices at all to work.

But as it is, you have small, self powered USB devices working and the trouble is with larger, external or system powered USB devices.

You can generally get a decent power supply for £15-20.

Ah, thank you, I hadn't really thought about the power supply... It does sound like that could be the problem.

It's a custom build and it's not too old. It's also got a 750W PSU in it already. Do you think it's dodgy, or just not enough for the system? It is chock full of drives in there...

But does that explain why the front usb ports don't work but my pci card and built in ones do? I suppose it's just the power distribution.

Edit: Ooh... I've just had a look at a 'power supply calculator' and it recommends 848 W for my system. Yeah... I might need a new PSU. But it was working for a while...

Oh well, I suppose I will run off and cry in a corner about spending another £100 on this system! Thanks for the help.

Yeah, sounds like you are running some sort of super computer

You would probably want a 900-1000W PSU just to be on the safe side. Or take out some hard drives.

Take out some hard drives? What nonsense I only have four hard drives and each is terribly important (and not at all filled with junk!). It's the three graphics cards and dvd drives that are giving me trouble...

Would you believe it was going to be a 'cheap' build when I started out?

*scuttles off to buy a new PSU*