What accounts for the difference in my Wireless 802.11n adapter speeds?

ti57 used Ask the Experts™
Greetings.  I have one newer laptop - a Thinkpad x300 - which came with a b/g/n wireless card installed.  We just got a new wireless N router and it zips along - says its got 130 Mbs throughput.
Meanwhile, I've got an older Thinkpad x40 which has only a b/g wireless card installed.  So I went for an 802.11n wireless USB adapter - it only seems to get 65Mbs for a transmit rate when placed on the same network.

My question is, what is this USB missing that the installed card has which allows for greater speed?  And what should I be looking forward in an adapter to get the fastest speed... (USB vs. card? Different feature set?)

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It sounds like your wireless N router may be made by one of the companies that don't support wide channels on 2.4GHz (e.g. Cisco, Apple, Intel, et al), otherwise you might connect as fast as 300Mbps instead of only 130Mb/s.

If you want to stick with a USB adapter, I would use one that supports 5GHz also. The only ones I found with a quick search are Orinoco - e.g. http://www.provantage.com/proxim-76298~APRX906Y.htm - and D-Link's DWA-160 - http://www.dlink.com/products/?pid=656 (about $67 on amazon). And you probably should stick with a USB adapter, unless you're adept at tearing the x40 apart to mount multiple 2.4/5GHz combo antennae inside it.

You might find a 2.4GHz-only (b/g/n) mini-PCI card for about half the cost of the dualband USB adapters, but be aware IBM laptop's are notorious for the '1802' error... they put a check in the BIOS to look for a string placed in the generic cards they purchase and then rebrand with the IBM logo. You can defeat that on most of their laptops by using a program called 'no-1802' - it flips 1 bit in the CMOS and the fix lasts until you have to replace the CMOS battery (ergo it can also be undone by removing the CMOS battery for 15 minutes or so). Another option is to change the ID in the card itself. Here's a site that explains it in detail - http://www.thinkwiki.org/wiki/Problem_with_unauthorized_MiniPCI_network_card (a working link to the 'no-1802' program - for floppy or CD - is all the way at the bottom of that wiki, under 'External Sources').
There are a variety of reasons that wireless N routers can go slower than their rated speed. Here is a link that explains some of the reasons you may be encountering an issue.


Distance from the transmission point could be an issue, as could having g/n clients connecting to the same router, instead of only n. Hopefully the article helps clarify (and correct) the issue you are having.


Perfect in combination.  Thanks.

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