What are 1% Lows? How to monitor (and fix) stutters in your PC games

Stutters, hitches, frame drops, lag... whatever you call them, we all experience those “hiccups” in the middle of a game. Even if your overall frame rate is high, these occasional blips can really mar the experience of an otherwise beautiful game. 1% and 0.1% lows aim to measure and quantify these stutters, so you can find the cause and hopefully smooth things out.

What are 1% Lows and 0.1% Lows in gaming?

To determine how “smooth” a game runs, we usually measure the number of frames generated every second, — which we call the framerate. The more frames per second (FPS), the smoother the game feels. But framerate fluctuates as you play, since it’s affected by the number of characters on-screen, the complexity of the shadows and lighting, and other features of the scene being rendered. Turn your character 90 degrees and you might experience a slightly different framerate than you did a second ago. That’s completely normal.

So to measure a game’s overall performance, we usually refer to the Average FPS of the game. It’s exactly what it sounds like: the average framerate within a specific period of time (usually a few minutes of play). This gives you a quick metric for how a game performs: a game running at 200 FPS is going to feel much smoother than a game running at 30 FPS. But it doesn’t tell the whole story. Occasional stutters may make things feel choppy even if they don’t bring the average framerate down.

It’s like if you were taking a day-long road trip on a freeway but had to stop at five toll booths along the way. It may be true to say your average speed was 75 miles per hour, but it doesn't communicate how significant those interruptions may have felt in the moment, even if they're brief.

Reviewers and enthusiasts need a way to measure the impact of these stutters in-game, which is how 1% and 0.1% Lows entered the lexicon:

• 1% Low refers to the average framerate of the slowest 1% of frames within a certain period of time. The lower this value, the more noticeable the stutters feel.
• 0.1% Low is the average of the slowest 0.1% of frames. These may be larger stutters that happen less often.

In other words, these values help to measure the consistency of frames, not just the average speed. The bigger the difference between your average framerate and the 1% Low, the more noticeable the stutter. And the more often they happen, the more they’ll be represented in the 1% Low value (vs the 0.1% Low value).

What causes bad 1% and 0.1% Lows?

Every game will have 1% Lows that dip below the average framerate. Take the graph below, for example — in this game, framerate hovers between 80 and 100 FPS most of the time. That’s normal, and you’ll even see a few occasional dips into the 60s. Those dips would appear in your 1% Lows, but in this case, they're not too bad.

But now let’s say the framerate graph looked more like this:

All of a sudden, those dips are much deeper, causing strong hitching in-game. It’s these kinds of stutters, the ones that completely halt your momentum for a split second, that can really grind your gears. And this will manifest as 1% Low values that are much lower than your average framerate.

Annoyingly, they can be caused by a myriad of things — but it’s usually a bottleneck somewhere in the game’s pipeline. A frame may be delayed due to:

• CPU Bottlenecking: If the processor has to run a complex physics calculation or other tasks, it may hitch for a moment before that big explosion.
• Shader Compilation: Games that compile shaders on-the-fly while you play may stutter when loading new assets. (This is why some games will compile shaders at launch instead.)
• Lack of available RAM or VRAM: If your system isn’t able to grab assets from fast-loading RAM or VRAM, it may need to swap data from your slower storage drive, which will cause a hiccup.

These are just a few examples. Some causes you can fix, and some need to be remedied by the game developer.

How to monitor your 1% and 0.1% Lows in GPU Tweak III

If you want to measure your 1% and 0.1% Lows — maybe to diagnose and fix the problem — you can use ASUS GPU Tweak III, an app with lots of advanced tuning and monitoring features for gaming PCs. A recent update added the ability to monitor 1% and 0.1% Lows, so you'll need v2.0.7.3 or later before continuing.

Launch GPU Tweak III and click the OSD icon in the left sidebar. Under the Monitoring Data subheading, you’ll find all the different metrics you can add to the on-screen display while you game. Make sure FPS Avg, FPS 1% Low, and FPS 0.1% Low are all checked, and flip the OSD switch on. (To learn more about using these monitoring features, check out our full guide to the GPU Tweak III OSD.)

Launch your game, enter a mission where you want to measure 1% Lows, and start playing. You’ll notice that the Avg FPS, 1% Low, and 0.1% Low don’t populate with numbers right away — that's because they require you to define a period of time to log them. Press F8 on your keyboard to begin recording a log, and you’ll see those numbers begin to populate. Press F11 when you want to finish your logging session, and you’ll be given your final numbers for each of those metrics.

Note that these instructions assume the default key bindings; you can also customize them to your own preferences. Click the Settings cog in GPU Tweak’s upper-right corner and open the Hotkeys tab to choose your own keyboard shortcuts.

How to improve your 1% and 0.1% Lows

As you monitor your framerate, watch your other metrics to see if any others spike at the same time as the game stutters. If your CPU usage spikes to 100%, for example, then you know the culprit is CPU-related. If your RAM or VRAM are full, then you know to start looking there. Here are some things you can try tweaking to improve 1% and 0.1% Lows:

• Update your BIOS, GPU drivers, and other software. Occasional bugs can cause stutters in games, so research your CPU or GPU to see if you might need an update.
• If your stutters are CPU-related, try lowering CPU-heavy settings like NPC count, draw distance, or physics.
• If your VRAM is maxed out, lower your resolution or texture quality. (Or upgrade to a graphics card with more VRAM.)
• Enable XMP, EXPO, DOCP, or AEMP to ensure your system RAM is running at its rated speed. If you bought a DDR5-6000 kit of RAM but didn’t enable its memory profile in your computer’s BIOS, it may still be running at its slower stock speeds.
• If your CPU or GPU temperature exceeds its maximum, the chip may be thermal throttling. Try re-seating the cooler and make sure the fans are running properly. (Note that relatively high temperatures are fine and will not cause stutters; only temperatures exceeding the chip’s maximum safe value — usually 90-100°C or more — are worrisome.)

Unfortunately, not all stutters can be fixed. If the game in question has poorly implemented shader compilation, aggressive DRM, or other developer-side issues, then the problem can only be fixed with an update to the game. You might research the game in question to see if other users are experiencing the issue, and if it’s a known problem on that title.

Whatever you’re playing, our goal at ASUS is to provide you the tools you need to make the absolute most of your gaming PC. For more on GPU Tweak III and everything you can do with it, check out our full collection of GPU Tweak guides here.