Ethernet cable not detected, Windows 8.1

The cable works on a different computer, the computer gets wireless fine (typing to you from it) but will not read an ethernet cable. The motherboard manual (built the PC myself from components) says an LED should light-up if an ethernet cable is connected, no such LED appears when I connect the cable.

Thanks for any and all help.

From the manual of this MB (Page 20). If there NO LED=10 Mbps data rate, 100=green and 1000=orange. Also, there is new driver for your Realtek LAN came out on May, 13. Here's the Website: GIGABYTE - Motherboard - Socket 1150 - GA-Z87-HD3 (rev. 1.x)

You should first get something like the Ideal loopback tester to check the cable for possible bad wires. You can have a bad cable, but still have one computer over another be able to use it.

Might be a "Crossover" cable you are trying to use. Some network cards or routers can not tell difference from "Straight" cable.

After poking around reinstalling drivers etc. and nothing working I might add. It just started working for no apparent reason other than internet space magic. I must say though, the LED remains off, the activity LED flashes as it should, so my speeds are capped around 10 mbps. The other computer I ran this to was getting the full mbps down that it should.

Hmm So I tried fiddling with it again today, and it again would not recognize the cable. After a while it simply recognized it again. I changed some setting and it automatically disabled/re-enabled the thing to apply the setting, and it once again refused to acknowledge the ethernet cable inside of it. I put that setting back the way it was, and am now waiting for the cable to once more be recognized. Why on earth would this happen. After further fiddling, I have discovered how I can and cannot connect to the cable consistently. Note that earlier today I did not use this method and still successfully connected. I downloaded the realtek diagnostic tool, and this tool in particular. http://i.imgur.com/15KVHWa.png Every time I press refresh, the diagnostic tool detects what the current state is, while also changing what the current state is. If I'm connected, and hit refresh, it reads that I'm connected with my 10mbps, all the links are normal. Then it disconnects me. If I hit refresh, it displays that I'm disconnected, and then the connection is immediately re-established. What is the diagnostic tool actually doing? We should note that after a few minutes of being disconnected in this method, the connection will automatically re-establish, but it appears to immediately re-establish if using the refresh button.