Add this to the target line to get 1080P resolution.

+set r_customwidth 1920 +set r_customheight 1080 +set r_aspectRatio 1 +set r_mode -1 

More commands and info:

com_allowConsole [0,1] - If set to 1, allows the command console to be opened by using only the '~' key, rather than CTRL + ALT + ~.

com_showFPS [0,1] - If set to 1, shows the current frame rate in Frames Per Second (FPS) at the top right of the screen.

r_mode [-1,3,4,5,6,7,8] - This setting determines the resolution, as set in the in-game menus under Screen Size (See In-Game Settings section). The mode values are:

• -1 = Custom resolution. Use r_customHeight and r_customWidth to set screen width and height. Must be used for widescreen modes.
• 3 = 640x480
• 4 = 800x600
• 5 = 1024x768
• 6 = 1152x864
• 7 = 1280x1024
• 8 = 1600x1200

r_aspectratio [0,1,2] - This setting allows you to set the aspect ratio of the image, which is mainly used for displaying on TVs. The options are:

• 0 = 4:3 (normal)
• 1 = 16:9 (standard widescreen)
• 2 = 16:10 (nonstandard)

This guide will help setup some very handy settings that Counter-Strike: Source has for advanced users. I thought I would write an article just to give those of you who play CSS the MUST DO tips and tweaks for the game. This guide may be updated in the future so keep an eye on it from time to time.