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Hardware

What is refresh rate?

Refresh rate is how many times per second a display redraws the image, in hertz (Hz). It's not frame rate, the frames per second the GPU renders.

What is refresh rate?

Refresh rate is the number of times per second a display redraws its image, measured in hertz (Hz). A 60 Hz monitor refreshes 60 times a second; a 144 Hz monitor refreshes 144 times. Higher refresh rates make motion, scrolling and the mouse pointer look smoother. Common rates are 60, 75, 120, 144, 165 and 240 Hz.

Refresh rate vs. frame rate

Refresh rateFrame rate
UnitHertz (Hz)Frames per second (fps)
Set byThe display and the signal it receivesThe GPU and the software it's running
Fixed or variableUsually fixed; variable with adaptive syncChanges constantly with the workload

When the GPU renders fewer frames than the display refreshes, some frames are shown more than once. When new frames arrive out of step with the refresh, the screen can show tearing, with parts of two frames visible at once. V-Sync holds the GPU to the refresh rate; adaptive sync (VESA Adaptive-Sync, AMD FreeSync, NVIDIA G-SYNC) lets the display change its refresh rate to match the frame rate. Refresh rate also isn't response time, which is how quickly a pixel changes color, measured in milliseconds.

Cables and ports set the ceiling

Higher resolution and higher refresh rate both need more bandwidth, so the connection can limit what a monitor can do:

  • HDMI 1.4 carries 4K at up to 30 Hz; full 4K at 60 Hz needs HDMI 2.0.
  • Single-link DVI tops out around 1920x1200 at 60 Hz; 1080p at 120 or 144 Hz needs dual-link DVI or a faster connection.
  • Long or low-quality cables may work at 60 Hz but flicker or drop out at 144 Hz.

Lowering the refresh rate or resolution is a useful diagnostic: if the flicker stops, suspect the cable, adapter or port rather than the driver.

Setting the refresh rate in Windows

  1. Open Settings, System, Display, then Advanced display.
  2. Pick the monitor if there are several, then choose a rate from the refresh rate list.
  3. If the screen goes black or the monitor says the signal is out of range, wait: Windows reverts the change after a short countdown unless you confirm it.

A high-refresh monitor stuck at 60 Hz usually means the wrong cable or port, an adapter in the path, a rate never changed in Windows, or an outdated graphics driver. Some laptops also offer a dynamic refresh rate that lowers the rate to save power when the screen content is static.

For the CompTIA A+ exam

Core 1 (220-1201) objective 3.1 lists refresh rates among display attributes, along with screen resolution, pixel density and color gamut, and objective 5.3 covers display symptoms such as a flashing screen. Know that refresh rate is the display's redraws per second in Hz, not the GPU's frame rate, and that cables and ports can cap it.

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Related terms

DisplayPort

DisplayPort is a digital display interface standard developed by a consortium of PC and electronics companies to provide a high-performance digital connection for a wide range of devices, including monitors, projectors, and TVs.

dual-link

Dual-link DVI adds a second TMDS link to double the bandwidth of single-link, for resolutions such as 2560x1600 at 60 Hz. It carries video only.

GPU

A GPU (Graphics Processing Unit) is a specialized electronic circuit designed to rapidly manipulate and output computer graphics. It is primarily used to accelerate the rendering of 2D and 3D graphics, as well as perform general-purpose parallel computing tasks.

HDMI

HDMI (High-Definition Multimedia Interface) is a digital audio and video interface standard that provides a single cable connection for transmitting high-quality uncompressed video and multi-channel digital audio between compatible devices such as computers, displays, and home entertainment systems.

high-refresh

High-refresh refers to display technology that provides a high rate of screen updates per second, resulting in smoother motion and reduced perceived blur.

native resolution

The optimal display resolution at which a monitor or screen produces its sharpest image, corresponding to the exact number of physical pixels available on the device. This is the resolution at which each pixel displays one dot of image data without scaling or interpolation.

pixel density

Pixel density refers to the number of pixels per unit area, typically measured in pixels per inch (PPI) or dots per inch (DPI), which determines the sharpness and clarity of an image or display.

screen resolution

Screen resolution refers to the number of pixels displayed on a digital screen, typically expressed as the width and height in pixels.

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