Most of the iPhone users reported difficulties in getting iPhone to sync with Windows 7 system, particularly 64-bit Windows 7 systems based on P55 chipset.
The iPhone is usually recognised, but iTunes complains that it cannot connect to the unit because of an "Unknown Error" - 0xE8000065.
Most of the reported issues resolved disabling USB power management.
Please follow the steps below :
- Click Start, type DEVMGMT.MSC and press enter to launch device manager.
- In device manager click view devices by type.
- Expand the Universal Serial Bus controllers section of the tree, right-click each USB Root Hub entry in turn, select Properties > Power Management, and clear "Allow the computer to turn off this device to save power".
- Reboot the PC and try syncing the iPhone and iTune again.
Note : Using the above tweak resolved 5/8 reported issues. In case if your issue is not resolved the use the Ask me section on this website.