Getting AC 5ghz speeds on windows 8.1

Ok I have an Asus AC66u with Merlin build 374.400 build as it was the last one confirmed by many people of it being stable. I have a pc with windows 8.1 about 2 feet away in another room. It has problems getting more than 100Mbit/s speeds. My wireless N/AC adapters are:

edimax AC1200 model# ew-7822uac 

edimax nano usb adapter model# EW-7811Un

The AC1200 does only 144.5Mbps and maxes out at around 12-14MB/s. The Nano by itself maxes out at around 10-11MB/s

Asus router has both 2.4Ghz & 5Ghz on, Windows 8.1 only sees 2.4 band, what am I doing wrong?


yea I have a smart TV & Roku box, does that mean 5ghz isn't enable when 2.4ghz is on?