Dual Monitors Not Working- Radeon R7 graphics

Hello!

I am a brand new Linux user and recently built a desktop with an AMD a10 7870, dual booted with windows 10 and ubuntu 16.04 64 bit. Only one of my monitors shows any video, even though ubuntu detects and recognizes both in the system settings. The monitor that isn't working is old, a Samsung SyncMaster 175v, coected with a VGA. I haven't downloaded any drivers, just am using whatever was downloaded when I installed Ubuntu. Hoping to figure out whats wrong. Thanks!