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hey, been lurking around this site for years, finally registered as i have an unusual problem. I have an Asus m2npv-vm motherboard, and the usb ports are acting very strange. Neither of my flash drives (4 & 8 gig) will recognize, both show as unknown, as does my galaxy s2 when i put it in storage mode. My microsoft wireless mouse and an old usb to lan adapter i have both recognize fine. I dont have any other usb peripherals to check at the moment, but so far it seems only storage devices will not recognize. Looking for input on the matter. This system (athlon x2 4200+, 2 gig ram, radeon x1950 pro) is going to be relegated to HTPC duty in a week when my i5 build shows up. The usb wont be a big problem then, but if i do decide to sell it, i would like to know if there is a way to fix the usb problem, or if my board is just on its way out.

That could be a Windows problem. Do you get the "A USB device connected to this computer has encountered a problem" message, or does it just never mount the drive in My Computer?

One way that can happen is when the drive gets "stuck" on a letter assignment that is already in use, especially if you have recently added another disk, opitcal drive, or virtual CD drive emulator to the system. Insert a drive and then check out the "Storage/Disk Management" section of "Computer Management" (Control Panel => Administrative Tools => Computer Management). If Windows has found the drive, it will be listed there. If it has a conflict over a drive letter assignment, you can also fix it there.

Try booting from a Linux live CD, and see if it will recognize the USB flash drives. That will tell you whether the problem is with the ports or the Windows installation.

Visually inspect the motherboard for bad (bulging/leaking) capacitors. Failing caps can cause random weird problems.

Even if the USB ports do turn out to be bad, if everything else on that board still works you can drop a PCI based USB card in there for under $10.

It is probably a signal integrity problem with the wiring that goes between the motherboard and the case. The cabling is supposed to have a precise wiring impedance to maintain the quality of the high-speed signalling which USB requires, but I have has two case kits now with horrid cheap wiring. I have had to go the distance myself and create my own wire harnesses to get performance back, though I doubt that is what you will want to do as it was a giant PIA. In my case I went from unusably slow problems, not mounting, and plenty of lockups when using USB peripherals, to expected high performance with 0 problems after changing out the wiring.

FYI to make the wiring I just picked up some quality USB cables and chopped then connectors off and re-wired to the connectors on the inside of the case tossing out the old wire. The difficulty is the wires used in the cables I purchased were pretty small and difficult to wire into the connectors, but I have the tools to do it plus some shrink tube to help hold them in place. It i best for you to locate better wires and be done with it.

So likely not hardware or drivers, but the wires included in your case. See if you can find a source for new ones.

It's easy to check for signal integrity issues by plugging the thumbdrive into one of the rear ports (if you have ports that are directly on the motherboard and ports on a separate rear slot bracket, test using the motherboard ones). If the rear motherboard ports work but the front case ones don't, then the culprit is almost certainly the USB wiring.

Thanks for the replies, i havent even plugged in the front usb ports yet. Strictly using the onboard ones. This happened under xp, and have since done a fresh install of 7, where the problem still exists. i have a pci usb card with 2 ports and of course that works fine. So for the time being, i plug the phone and flash drives and phone into the pci card, mouse and whatnot into the board. windows tries to find drivers, but the flash drive comes up as unkown device. Disk management shows nothing for flash drives installed. Im starting to believe it is a bad board

Okay, so based on those extra notes, it's probably electrical.

If the ports on the back have been used a lot, another possibility is that some solder leads are cracking. If you have soldering skills or a friend who does, try re-flowing the solder connections that feed the USB port head. It's possible one or more of them have a hairline fracture that is interfering with the signal integrity. Also note JBI's comment about capacitors, as there may be a couple buffer capacitors near the port head that are going bad and feeding pulsed power down the port rather than smoothed power.

Low-speed, internally-buffered peripherals such as mice and keyboards are much more tolerant of these failure modes than a data storage device.

after a quick look, the caps seem to be fine. I was given this board and cpu, so i dont see myself putting too much effort into fixing it. my wifi card works, and i have a component out bracket, therefore it is most likely going to just run XBMC and be connected to my projector in my livingroom. I thank you all for the help, I figured the board was bad, but thought i would check and see if anybody had this type of issue. i dont need the usb ports for streaming movies from my other pc, so im not too worried about fixing it. Just looks like it will finish its life as an htpc.

Try connecting the front-panel ports -- you might get lucky.

i actually tried that after, same issue. certain devices work, others dont