Hi:
First, make your set of W8 recovery media before installing W7 64 bit. See the info below.
Next, you need to change a bios setting in order to install and continue to run W7 on your PC. See info below.
Once Windows 7 is installed...
First install the AMD Chipset Driver. You want the 49.7 MB file.
http://support.amd.com/en-us/download/chipset?os=Windows 7 - 64
After you install the AMD chipset driver, you can use most of the W7 x64 drivers from this model, except the wireless.
DO NOT USE ANY BIOS OR FIRMWARE DOWNLOADS FROM THIS LINK
Use this driver for the wireless.