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ASUS P8Z77-V LK Weird USB Issue

Last response: in Motherboards
November 6, 2012 5:47:02 PM

I have 2 USB ports that are behaving oddly on my ASUS P8Z77-V LK. Of the 4 USB ports on the back, 2 work fine, the other 2 will show the usb devices as being powered on during post, but as soon as Windows 7 loads, the lights go out on the USB devices and it's like the USB port is dead. It seems like they are working, at least for power all the way until Windows loads. Any ideas?
a b V Motherboard
a b Ĉ ASUS
November 6, 2012 6:30:46 PM

If possible, put a Linux Live distribution (like Knoppix) on a USB drive, and then see if you can boot off of it. That should tell us pretty quickly if it's a hardware or software issue.
November 6, 2012 7:26:23 PM

will do tonight when i get off work
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a b V Motherboard
November 6, 2012 7:39:46 PM

I think 2 of the USB 3.0 ports in the back are controlled by an AsMedia controller which may need to be activated in your BIOS.
a c 431 V Motherboard
a c 111 Ĉ ASUS
November 6, 2012 7:40:22 PM

chech in your bios under usb device that ehci is enabled. on some os there has to be a usb hand off from the bios of the mb to the os on the pc. if it not turned on the usb device will turn off intill plugged back in. also check that you have the newest intel chipset driver and usb 3.0 driver.
November 9, 2012 12:24:42 PM

I got into bios and enabled ehci hand off and intel xhci, still no joy. It's weird, the usb devices are getting power while it;s in bios, or even while it's booting up, but as soon as windows loads, devices plugged into two of the ports go dark.
November 9, 2012 12:37:27 PM

So this is solved. There are two sets of USB drivers on the Asus Mobo CD. INTEL and ASMEDIA, after installing the ASMEDIA USB drivers from the CD, the other 2 ports started working.

Why would Asus put two usb controllers on the same board? Why not just have 4 ports powered by intel, seems odd having 2 intel and 2 ASMedia
a b V Motherboard
November 9, 2012 4:28:01 PM

I think because there is a limit to how much the one Intel controller can handle, so they add an additional controller that has slightly different advantages/disadvantages to provide a little variety. I believe the AsMedia ports either work better or worse for RAID configurations or something like that.