Do you really need a 120Hz or faster monitor?

Samsung SB971 Monitor front angle

If you’re looking for a new monitor, you may be bewildered by the options available now. The last five years have seen the average monitor’s feature list swell to include better panels, higher resolutions, and more inputs.

One of the most recent features to hit mainstream monitors is 120Hz panel technology, and a few very recent models have upped the ante with 240Hz panels. This is among the most confusing traits for consumers, because the name doesn’t provide much explanation, and unlike most improvements, this one doesn’t enhance color accuracy or resolution.

So should you wave off these 120Hz monitors, or is this confusing spec one that you should absolutely be chasing in your next display? Here’s what you need to know.

What does 120/240 Hz mean?


Casual users often assume that “120Hz” has something do with performance because it seems similar to the way processor clock speeds are described. In fact, the term describes something a bit different; refresh rate.

Refresh rate is the number of times per second a display refreshes its image. Since movement is displayed by the difference between frames, the refresh rate effectively places a hard cap on the frame rate visible.

Note, though, that refresh rate is not the same as frame rate. Refresh rate is an attribute of the monitor, while frame rate is an attribute of the information being sent to it. Improving refresh rate will not improve frame rate unless the frame rate of the content you’re viewing can exceed the refresh rate of your current monitor.

Now you know what the numbers refer to, but specifications don’t tell the whole story. Here are three reasons why you might want a 120hz/240hz monitor.

1. Improved motion resolution


The first major benefit of a higher fresh rate is improved motion resolution, which can be described as the perceived sharpness of a moving image. Blurring occurs because of how the human brain processes the set of individual frames a monitor displays. The brain blurs together the series of frames to create a sensible moving picture, but some detail is lost along the way. 

A higher refresh rate helps to decrease the blur by giving our brains more information to act on, in turn reducing perceived blur. However, unlike computer hardware, our brains aren’t all made to the same specification. Some people notice the difference between a 60Hz and 120Hz display immediately, while others can’t see what everyone is all worked up about. The difference between 120Hz and 240Hz is even more subtle, though some still see a benefit.

If possible, try finding a 120Hz monitor in a store. Many have motion demos running to show off the feature. You might also refer to past experience; if you immediately notice stuttering or blur at the movie theater, or on your television, you’ll probably notice the difference. People who’ve never had a problem, however, may not see an improvement.

2. Reduced screen tearing in games


Refresh rate and frame rate are not the same thing, and in games, a difference between them can cause an artifact known as screen tearing.

This occurs when a computer’s video card is spitting out frames at a rate well beyond the refresh rate of the monitor connected to it. Because more frames are being spit out than the monitor can handle, half-frames are sometime shown together on the screen, a distracting problem even the least sensitive viewer will usually notice.

Take Diablo 3 as an example. This game is not difficult for most computers to handle, so many gamers will see it play at a frame rate beyond 60 frames per second. However, a 60Hz display only refreshes 60 times per second. This means gamers are not fully benefiting from the enhanced responsiveness of the higher frame rate, and may notice tearing as the display fails to keep up with the data feed to it. A 120Hz display refreshes twice as quickly as a 60Hz display, so it can display up to 120 frames per second, and a 240Hz display can handle up to 240 frames per second. This will eliminate tearing in most games.

V-sync is a common solution to tearing on 60Hz displays, as it caps the frame rate of a game at 60 FPS (in most games). But V-sync can introduce input lag and it limits the performance potential of a PC. Many gamers find a game running without V-sync on a 120Hz monitor more responsive than the same game running with V-sync enabled on a 60Hz monitor.

3. Better responsiveness in games


The refresh rate of a monitor has an impact on input lag. A 60Hz display, for example, will never have a visible input lag below 16.67ms, because that’s the amount of time which passes from one refresh to the next. A 120Hz display haves that time to 8.33ms, and a 240Hz display further reduces it to 4.16ms.

Decreasing lag by less than ten milliseconds may not seem important, and for many people, even gamers, it’s not. However, input lag can be a problem for hardcore gamers, or for those who like games to feel as smooth as possible. This is, once again, an issue some people will notice more readily than others.

Do you need really need a 120Hz or 240Hz monitor?

Two of the above points relate exclusively to gaming, and gaming alone. This leads to an obvious conclusion: Gamers should buy. But what about everyone else?

While the improvement in motion resolution is notable, its benefit is often hard to notice. Televisions, which also advertise 120Hz or 240Hz panels, further improve motion quality with image processors that change the input sent to them. Many can even add frames, effectively increasing the framerate of content. Monitors, however, have no processor; the input sent is what’s displayed. This minimizes the benefit of the panel when viewing video content. An improved refresh rate also does not guarantee the elimination of “ghosting,” an artifact common to LCD monitors which causes moving objects to leave one or more faint trails behind them. 

In short, consumers who don’t game will struggle to notice a difference. Spending money on improved image quality, rather than improved motion performance, is usually the better choice. There are many great IPS displays on the market (like the Dell Ultrasharp series) which rely on 60Hz panels but are otherwise superior to most 120Hz monitors on the market.

Image source: Game Trailers Forum