Open Battlenet settings by clicking on the Battlenet logo in the top left corner of your Battlenet launcher and selecting
Settings:
- Go to Game Settings
- Click on World of Warcraft
- Check the Additional Command Line Arguments box
- Type -console (dash console, no space)
- Click Done
Then log in to World of Warcraft:
- Press ~ (Tilde - on a standard US keyboard this is shift-`, below the Escape key, right before the 1 key.)
- A command line console will open at the top of your screen
- Type GxAllowCachelessShaderMode 0
- Type gxRestart
- Press Escape to close the console