Windows 7: PC stopped recognizing my external HD but other PC/Laptops still do

One day my main desktop stopped recognizing my external 2.5 HD (uses to 2 usb ports for power). Even in "disc management" its not recognized, but the interesting thing is, all other usb devices work perfectly even all thumb drives.

I originally thought my HD was starting to fail, but later realized it worked on my laptop and htpc. Both computers recognized the external drive w/ no problems 100% of the time.

Things Ive done since:
1.Reformat main desktops HD and reinstall windows 7 (32)
2.Reformatted external HD (did it on the laptop)
3. Tried all usb ports with same result

* In the Bios, under "usb config". The drive IS recognizable. But when windows starts up, nothing happens.




But my main desktop still wont read or recognize my external drive.
Im guessing its my motherboard (Asus P5KC) or PSU thats giving me the problems?

Is my external drive not getting enough power?
Is there any other way to trouble shoot this?

Go to disk management and see if it is recognized there.

I started having a similar problem after finally installing Windows 7 SP1--had to run the Windows Update Fix in order to get THAT to work!.

It wasn't just external HD, although that's what I noticed first. I unplugged my keyboard, because one suggestion was too many USB devices drawing too much power. When I plugged my keyboard back in, guess what? NO KEYBOARD!

I do IT support for a living, but my own systems are often put off 'until I have time'.

Long story short, fixing this required a BIOS update. I have an Intel dq45ek mobo, and there was a BIOS update that related to 'legacy USB device recognition'. Why this became a problem after the SP1 update, I don't know, but I tried resetting the CMOS (worked for others), tried removing devices through device manager (except did not try removing all the USB controllers, that was going to be my next step), tried searching (for hours) through dozens of forums), ...

Now onto the next project..

Steve

thanks for sharing Steve, Ill give some of those a try. If all else fails, Im getting a new mobo. This thing has been giving me problems since day one.