Wireless Monitor and Wireless N card Issue!

The problem may also be that if your new card is more sensitive you may be picking up additional signals perhaps from your neighbors.

Remember the world record for WiFi (under controlled conditions) is 201 kilometers/125 miles! This was set in Northern Nevada using two large old parabolic satellite dishes! So you may be getting a neighbor down the street or you may be getting a closer cordless phone signal if they are on 2.4gHz or you may be getting a stray microwave oven leak emmision from the kitchen.