tl;dr

Unless you have a good reason not to, leave vsync ON.

I felt compelled to write this entry, because, in my personal testing, I saw some concerning things with leaving vsync off, that most people don’t seem to be aware of. The general consensus seems to be that you should always leave vsync off unless you have problems, whereas I believe you should do the exact opposite, which is to leave it on unless you have problems.

what is vsync

Simply put, vertical synchronization (v-sync) will prevent games from drawing more frames than is necessary because your monitor has a physical limit to how fast it can refresh the screen (generally your refresh rate will be 60Hz unless you specifically bought a gaming monitor).

I won’t pretend to know everything about it, but roughly speaking, it appears that your refresh rate is linked to the max FPS your monitor can display. Ergo, 60Hz equals a max of 60 FPS, 120Hz is a max of 120 FPS and so on.

why would I want/not want it

Frankly, I only know of one plus for most people to leave vsync off, so let’s address that first: input lag.

This apparently will even vary from game to game, but by leaving vsync on, you may notice input lag. Now, if you’re playing a single player game, you might not even care, but if you’re trying to eek out every last drop of performance so you can rack up your kill count in an online match, then you will care.

Another reason to leave it off (that is far less common) is speedrunning. Take Tomb Raider 2013 for instance: some glitch tricks will only work with a high framerate, and if your vsync is capping your FPS at 60, you’re going to have a bad time.

common advice about why you should leave vsync on

In brief, screen tearing. It’s the phenomenom where visuals from more than one frame are on the screen at the same time.

I could try to explain what it looks like, but it’s far simpler to say that you should check out the image example on the wikipedia page.

From my research, this was basically the only reason given as to why you would ever leave vsync on.

some uncommon advice about why you should leave vsync on

Again, from what I’ve read, the general consensus is to just leave vsync off, but this misses two important points that I’ve see few people bring up:

  1. computer power usage
  2. computer heat/longevity

In my testing with Tomb Raider 2013 (again, it requires a super high framerate to execute certain glitches), I noticed some disturbing trends when I’d turn vsync off.

First, was the immediate and noticeable change in CPU fan speed. Not only had it become louder (more so, it went from inaudible to definitely audible), but I could start to feel the heat coming out the back of the computer.

Now, if you’re an overclocking enthusiast, you’re probably not going to be running on the stock Intel fan like I am, so perhaps this won’t affect you hardly at all. But in my rough testing by looking at Speccy, here was what I noticed:

CPU temperatures

55ºC CPU temp with vsync on and a full 30+ degree boost by turning it off (88ºC). Ouch.

GPU temperatures

Not as bad, but still notable: 49ºC with vsync on; 64ºC with it off.

Possibly even more disturbing is that these were the immediate effects; it wasn’t like this was an hour after turning vsync off (now I will admit that I didn’t test it long term, so it’s possible that temperatures would’ve just stayed high but not gotten worse over time).

Now maybe these temperatures are acceptable, but I don’t appreciate having a space heater in my room in the middle of summer and I have serious concerns about how this extra heat could effect the longevity of the components inside of the computer.

power usage

Probably one of the big reasons that this is seldom brought up is that people simply don’t know about it. Not everyone owns something like a Kill A Watt after all.

140-160 watts with vsync on; 350 watts with it off.

So basically, my computer used a full 200 watts more with vsync off. And given that it was averaging about 150 watts to begin with, that means that power usage had more than doubled.

Now will this break the bank? Maybe not. Frankly I couldn’t even find my electricity company’s cost per kilowatt hour, but a random energy calculator I used defaulted to 12 cents a kilowatt hour, so let’s use that as a baseline.

the cost of that extra 200 watts

If you gamed for 1 hour a day, it would cost you an extra $0.72/month. 2 hours a day would be $1.44/month. And so on.

So the cost may not be a great incentive, but again, if you don’t need for vsync to be off, then why bother?

conclusion

Of course, my testing was limited and only represents how my particular computer handled things, but I can’t fathom that there would ever be a situation where things would be equal. Sure if you’ve got an aftermarket cooler installed, CPU temperatures might be similar, but you’ll still have the extra heat on your GPU, and your power usage will still increase.

Actually, I can say that there probably would be one situation where things would be similar with and without vsync, and that would be where your computer was almost already at max with it on and so turning it off barely gave you any framerate boost.

At the end of the day, there are so many downsides that unless you’ve found a specific reason to leave vsync off, simply keep it on. You’ll save energy, ambient heat, and maybe your computer will even live longer.

That’s my take.