Download speed is lower on one computer.

Hello i just recently had installed Comcast cable internet into my home today. I use 2 computers which are connected to a router. My computer downstairs is short-wired to the router. It gets a 20 mbps download speed. My long 60 ft wire running upstairs goes to my comp in my room. It downloads at 5 mbps. Now when i had DSL, both computers had the download speed.

I've ran the tweak test from broadband reports, turned off firewalls, and configured router yet the download speed on this comp is substanially lower then the one which is short wired. Now i know it is probably not cause of the wire length, since they were the same speed when i had DSL. I really am puzzled by this.........
Someone help out?