If you wish to rotate your LCD screen there are a number of factors to consider.


Commercial or domestic

Some screens just were not designed to run in portrait.

Domestic televisions for instance are not designed to run in portrait and doing so would usually void the warranty.

The reason fro this is due to the thermal management design, as the units are vented in a way to vent out the top of the screen.

Rotating them can trap heat and significantly reduce the lifespan of the screen. 
Another factor with domestic televisions is  they often have asymmetrical bezels and look strange in portrait because of this.


Most commercial displays (excluding hospitality series) are designed to either operate in portrait or landscape. However you should check the manual of the specific model you are considering running in portrait.


Fans

Some panels have different fan settings to operate in portrait, if you screen has nay options to specify this ensure you do.

Note some panels require you change the on screen display (OSD) to be in portrait and the fans will automatically adjust. 


Clockwise or anti-clockwise

Typically screens will be designed to rotate one way and not both, this again is due to the thermal management design.

It's best to always check the manual for your specific model however in our experience the below table shows the most common configuration for popular brands.


Brand Rotation
NEC Clockwise
Samsung Clockwise
Sharp Anti-clockwise
LG

Clockwise

Panasonic Clockwise
Phillips  Clockwise