Download PowerStrip from this link
http://downloads.guru3d.com/download.php?det=169
Install it in your computer.
After installation reboot your computer and you will find PowerStrip icon in your System tray botton right corner of the screen.
1. Go to custom settings and create an .ini file.
2. Now go to Strat -> Settings -> Control Panel -> Click on Display - Now opens Display properties.
3. Click on Settings tab - > Click Advance -> Click Monitors Tab -> Properties -> Click Drivers tab -> Click Update Driver
4. Yes, this time only -> Click next
5. Install from a list or specific location (Advanced) -> Click next
6. Search the best driver in this location -> include this location in the search: -> Click browse button to select the exact location of the new .ini file you created using PowerStrip
7. Click next -> Click next again to install it.
Restart your computer and change display properties to this new resolution
or else select it from the PStrip icon in system tray to set this resolution.
Let me know if this helps you.
Gyan.