Hello.
I have 951G router. Also i use 250 mbits internet connection. But today,when i attached my router,in computer,it shows only 150mbps.
Then,i loged in Quick setup(as showed in QSG and WG paper),and then i spoted,that i can’t set on 40mhz. Can some one help me? How to configure or set that my router can use all 250mbps not only 150mbps? Thank you 
I can give more information if neded.
You need to have both chains enabled on 951g and on your notebook also. Don’t expect you can pass real 250mbits over wifi in common conditions.
Hmm,please explane me how to do it? I am not pro at this 
I use Win7
Hello… Anyone??
At first your card must be dual chain. Then the second chain mustn’t be disabled in the device parameters. In the router both chains have to be enabled. See rx-chains and tx-chains parameters in the manual http://wiki.mikrotik.com/wiki/Manual:Interface/Wireless
You don’t need to be a pro to use Google and read the manual when you got a hint what are you should look for.
Are you sure your laptop is capable of more then 150Mbps wireless? Check your wireless card settings- on Windows wireless cards are usually set to 20MHz only for 2.4GHz band.
150mbits shown means single chain on 40mhz, not the 20 MHz channel width. http://mcsindex.com
You are right, still my first question stays. Is OP’s laptop capable of more than 150Mbps wireless? It’s possible that the wireless in his laptop is single-chain only.
I wrote the same in the beginning…