Activate Hidden ‘Ultra High’ Setting in Valve Games
How to Activate the ‘Ultra High’ setting in Valve Source Games (Portal, HL2, TF2, etc):
1. Active the console under the advanced keyboard settings in the options menu.
2. Hit ‘~’ (tilde) to activate the console and enter ‘mat_picmip -3′ to activate the ‘Ultra High’ setting. Feel to free to go lower if you think your hardware can handle it.
NOTE: If this slows your PC to a crawl then you obviously do not have the hardware to run the ‘Ultra High’ settings.