Network adapter won't work on my dell Inspiron?

had this nagging issue with win 7 that it just won't recognize it when i plug in the network cable, though i checked in the network connections page, the network adapter icon used to appear and disappears at random.

Now, that i formatted the system and installed win 8, the problem still persists, in fact, the LAN icon appears, but nothing happens when a network cable is plugged in,

I've checked the cable with other PCs, it is fine, please suggest. I've updated the driver and stuff like that