Is the latest MacBook Pro capable of displaying 120fps on an external 120+Hz monitor? Does macOS allow such a high frame rate?
macOS High Sierra (10.13.2)
MacBook Pro - Technical Specifications - Apple scroll down to Video Support.
MacBook Pro - Technical Specifications - Apple scroll down to Video Support.
The fastest refresh rates are provided by [Mini] DisplayPort and [Full size] DisplayPort interfaces. DisplayPort displays have an internal screen buffer, and the refresh rate from their internal buffer to the screen itself are not limited by the computer refresh rate.
Once the screen is drawn, DisplayPort cable sends only the changes in most cases. The "heartbeat" refresh of "legacy" displays (30 to 100 times per second) is not present.
--------
HDMI, on the other hand, was designed for 1920 by 1080p displays at 60Hz. It can sometimes be stretched to service higher resolutions, (under ideal conditions and special cables) to slightly more, but often falls back to slower refresh than 60Hz.
Is the latest MacBook Pro capable of displaying 120fps on an external 120 Hz monitor?
