What OS are you running? And what is your usual ISP connection speed? But before anything, check and DL any updates for your OS and motherboard chipset/gpu etc.... Next, Check in game settings on LFD2 for multiplayer and network. Also download latest punkbuster drivers.
Also if you could run this for me and post a screenshot here so we can see what your connection speed is-
Next(if still problem)
Contact your isp it has nothing to do with your GPU, also lemme guess its a motorola surfboard yes? That would be problem number one, they are absolute **** and have been known to be inconsistent especially with multiple computers on its network.