Acer forgot to place the chipset drivers for Aspire 4520 in Windows 7 x64, but you can use the one in Aspire 5520 that is the same exact notebook, but 15" version. 
Acer Support - Welcome to Acer Support
Seems like Acer likes to be tricky, huh?
Hope it helps you.
PS: Direct link for lazy people like me.
http://global-download.acer.com/GDF...tep3=Aspire 5520&OS=701&LC=en&BC=Acer&SC=PA_7

Acer Support - Welcome to Acer Support
Seems like Acer likes to be tricky, huh?
Hope it helps you.
PS: Direct link for lazy people like me.

http://global-download.acer.com/GDF...tep3=Aspire 5520&OS=701&LC=en&BC=Acer&SC=PA_7
My Computer
At a glance
@Home/Work: Windows 8.1 Enterprise x64@Home: Core [email protected] GHz / @Work: Core i3-...@Home: 8 GB. DDR3-1333 CL9 / @Work: 12 GB. DD...@Home: MSI N560GTX-Ti Twin Frozr II / @Work: ...
- Computer type
- PC/Desktop
- Computer Manufacturer/Model Number
- @Home: Built by me / @Work: Banghó Extrema
- OS
- @Home/Work: Windows 8.1 Enterprise x64
- CPU
- @Home: Core [email protected] GHz / @Work: Core [email protected] GHz
- Motherboard
- @Home: Gigabyte GA-Z87-D3HP / @Work: ASRock H61M-VG3
- Memory
- @Home: 8 GB. DDR3-1333 CL9 / @Work: 12 GB. DDR3-1333 CL9
- Graphics Card(s)
- @Home: MSI N560GTX-Ti Twin Frozr II / @Work: Intel HD 2500
- Sound Card
- @Home/Work: Realtek HD Audio
- Monitor(s) Displays
- @Home: Samsung T260 LCD via DVI-D / @Work: Acer AL1714 (VGA)
- Screen Resolution
- @Home: 1920x1200x32@60h / @Work: 1280x1024x32@60h
- Hard Drives
- @Home: 4 disks that results in ~4.3 TB. of usable space.
@Work: Western Digital WD10EARS (1 TB.)
- PSU
- @Home: Topower 650W / @Work: Shark Net 600W
- Case
- @Home: Euro Case Generic / @Work: Banghó Extrema
- Keyboard
- @Home: Genius (Spa) / @Work: Noga Net (Spa)
- Mouse
- @Home: HP Laser 2.4G Xa965 / @Work: Genius Optical generic
- Internet Speed
- @Home/Work: Fibertel 7Mbps/512kbps
- Antivirus
- @Home/Work: Windows Defender+Spybot 2+AdwCleaner
- Browser
- @Home/Work: Google Chrome (Dev)+Mozilla Firefox (Aurora)
- Other Info
- @Home:
Microsoft Xbox 360 wireless gamepad+USB receiver.
Microsoft Xbox 360 wired gamepad.
Logitech C910 Full HD webcam.
Generic 5.1 analog Home Theater.
@Work:
2-Way electronic keyboard/mouse/monitor switch.