The Intel® Wireless WiFi Link 4965AGN is designed with a 2x2 (2 Transmit/2 Receive) antenna configuration, thereby supporting up to a 300 Mbps data rate. The third, middle connector is auxilliary. Please see the product brief and the comment below about antennas. Although the latter discusses installing and upgrading, the concept applies to manipulating antennas. Another community member seemed to find 802.11n configuration settings that enabled his AP/router to connect at higher data rates.
Installing or upgrading the various Intel wireless adapters by end users is not supported by Intel. There are many reasons for this. I recommend that you review the information at http://www.intel.com/support/wireless/wlan/sb/CS-031167.htm and http://www.intel.com/support/wireless/wlan/sb/cs-006006.htm.
Specifically the Intel® WiFi Link 5300 and the Intel® Centrino® Ultimate-N 6300 have the same electrical requirements. However the 5300 comes in both a minicard and half minicard form factor. The 6300 comes in the half minicard form factor only. Some laptops do not recognize the half minicard adapter. Although it may appear to fit the adapter may not work with the laptop.
The Intel® Centrino® Wireless-N 1000 does not support 5GHz or 802.11a. Both the 5300 and 6300 support 5GHz. If you are looking to replace the 5300 and need to use 5GHz this would not be a good choice.
Another point I need to mention here is that many OEMs prohibit the replacement of the wireless adapter and will not recognize any adapter other than the one originally installed in the laptop. This is true of Lenovo. You will need to contact them to replace the wireless adapter.
Finally got this figured out. In case others have the same problem as I did (i.e., PC wouldn't connect at more than 54Mbps/wireless-G speeds) and want to avoid hours of frustration and deadends... To summarize what I did to get this to work
1. Have current Intel driver (on their website); Lenovo had not installed current driver on my new laptop; oh well
2. Set router to 20/40 Auto channel width, mixed n/g
3. Turn on WPA2/AES encryption
4. Enable WMM and QoS on router (QoS was already on for me, but people on Intel forum told me to check it was on so sure it must do something good)
Step 4 worked magic - went from 54Mbps to 270Mbps in a hurry. Speed fluctuates a bit it seems but still a vast improvement.
Thanks for the information. Unfortunately, the changes I made to my router to the settings listed in your post did not work. I also changed routers and still have the same problem. I now an connected to d-link DIR-625. My settings correspond with your post but I only get 65 Mbps. I have a clear path to the router and the router is only about 10 feet away.
Since I am experiencing basically the same problem with two different routers, could there be some issue with the card - I have updated it to the latest driver - or my computer?
I've had a similar issue with the 4965AGN that's onboard in my Acer Aspire 5920 laptop. It won't provide anything more than 65 mpbs no matter what I do/try. Other computers on my local network connect no problem at speeds > 150mpbs but the 4965 refuses to seemingly. I have the latest drivers, have tried all the settings mentioned in http://www.intel.com/support/wireless/sb/CS-030709.htm and it just won't step up. (Interestingly, the "Throughput Enhancement" setting is not an option that's available for setup........).