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I have a problem with my USB ports and I can't seem to pinpoint the problem. I'm hoping that I can get some idea as to how to troubleshoot my problem.

Problem description: I recently bought a USB Wireless Adapter in order to connect my Desktop PC to the WLAN. The dongle keeps dropping off connection regularly on average once a minute. And the connection is slow.

Motherboard: Asus P8Z68-V LE

USB ports connected: 10 (4xUSB2.0 front, 4xUSB2.0 back, 2xUSB3.0 back)

Wireless adapter: D-link DWA131

Mobile Phone: Apple iPhone 5

Operating System: Windows 7 64x

What I've tried:

  1. I installed a network scanner to determine signal strength. The PC/adapter combo is getting about 70% signal strength.

  2. I have a laptop that has an internal Wireless adapter. I moved the laptop near the location of the PC. The signal strength was above 90%.

  3. I installed the USB adapter on the laptop. I placed the laptop near the location of the PC. The signal strength was above 80%. And there is no drop out issue.

  4. I've isolated the problem to be on the PC.

  5. I used internet tethering on my mobile phone in order to test the USB ports. I get the same problem, the mobile phone keeps dropping in and out.

  6. I plugged the adapter and phone on all USB ports, and it is still dropping out on all ports.

  7. I've isolated the problem to be the Motherboard, USB hub. I updated the BIOS, and USB driver. Still dropping out.

  8. I noticed that when I used the mobile phone tethering method, the phone (iphone 5) is guaranteed to drop out and does not appear to charge if I jiggle the the 8-pin connector on the base of the phone. If I push the pin tightly on the phone, the phone starts charging, as soon as I let go, it stops and drops out from the PC. This is strange because this doesn't happen when it is plugged to the powerboard. Which means that the 8 pin connector is fine.

I'm not sure what the problem is. I assume that it is to do with the USB ports not supplying enough power which in turn causes the devices to intermittently drop out. The reason I say this is because the USB cable works fine when plugged into a powerboard with enough power supplied to the phone. Only when it is plugged into the USB port on the PC, does it drop out.

I can't seem to find any settings in the BIOS to increase the south bridge voltage so as to supply more power to the USB ports. Although this problem only occurs when I'm trying to hook up to a device supplying internet connection. My USB HDD, Flash drives, and Mouse and Key are working fine! Any suggestions please?

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