Understanding Response Time: GtG vs. MPRT and the Science of Overdrive

Introduction: The “1ms” Marketing Lie

If you walk into any electronics store, almost every gaming monitor on the shelf proudly claims a “1ms Response Time.” It sounds impressive, but for most people, it’s a highly misleading figure. In reality, a monitor marketed as 1ms might actually exhibit significant blurring, while a high-end 4ms panel might look perfectly sharp.

Why the discrepancy? Because “Response Time” isn’t a single measurement. It’s a complex dance of liquid crystals and electrical voltage. In this guide, we will pull back the curtain on GtG vs. MPRT, explain the physics of Overdrive, and show you how to identify and fix the artifacts that ruin your gaming experience.

1. GtG vs. MPRT: What Are They Measuring?

To understand speed, we have to look at two different phases of an image’s life on your screen.

GtG (Gray-to-Gray)

This is a measure of physical speed. It tells us how long it takes for a liquid crystal to physically shift from one shade of gray to another.

• The Problem: Manufacturers often only report the fastest possible transition (the “best-case scenario”). The average GtG on a “1ms” monitor is often closer to 4ms or 5ms.
• The Result: Slow GtG causes Ghosting—a faint, smeary trail that follows moving objects.

MPRT (Motion Picture Response Time)

This is a measure of persistence. It tells us how long a pixel is actually visible to your eye.

• The Problem: Even if the crystals shift instantly (0ms GtG), the image stays on the screen until the next refresh. As your eye moves to track the object, the static image is smeared across your retina.
• The Result: High MPRT causes Motion Blur. Reducing this requires technologies like Backlight Strobing.

2. The Science of Overdrive: Pushing the Crystals

Wait for it—how do engineers make crystals move faster than their natural physical limit? They use Overdrive (also known as Response Time Compensation).

Think of a liquid crystal like a heavy door. To open it to “50%,” you could give it a 50% push. But it would be slow. Instead, Overdrive gives it a 150% push for a split second to get it moving, then “catches” it at the 50% mark. This “voltage boost” significantly reduces response time.

3. The Artifacts: Ghosting vs. Inverse Ghosting

When you adjust the “Overdrive” setting in your monitor’s menu (often labeled as Normal, Fast, Fastest), you are choosing between two types of visual errors.

A. Ghosting (Undershoot)

This happens when your Overdrive is too low. The crystals haven’t reached their target color before the next frame arrives.

• Visual: A dark, blurry trail behind the object.

B. Inverse Ghosting (Overshoot)

This happens when your Overdrive is too high. The door was pushed so hard that it “swung past” the 50% mark and hit 70% before bouncing back.

• Visual: A bright, “neon” halo or glowing trail behind the object. This is often more distracting than standard ghosting and is a sign of a bad “Fastest” preset.

4. Oled Persistence: A Different Beast

OLED panels have a GtG (physical) response time of nearly 0.03ms. This is effectively instant. However, because they still use “Sample-and-Hold,” they still exhibit motion blur. This is why a 120Hz OLED looks as clear as a 240Hz LCD—the OLED has zero ghosting, but the same motion blur.

5. Identifying Speed Issues with Tests

How do you know if your monitor’s Overdrive is set correctly? You need to see a moving high-contrast object.

Use our Motion Test Tool for the “UFO-style” check:

1. Set the background to medium gray and the object to a dark color.
2. Observe the trail.
3. Ghosting? Increase your monitor’s “Response Time” or “Overdrive” setting by one level.
4. Bright Halo (Coronas)? Your Overdrive is too high. Dial it back from “Extreme” or “Fastest” to “Fast” or “Normal.”

6. Real-World Recommendation: The “Sweet Spot”

Most monitors have three Overdrive settings.

• Setting 1 (Low): Usually safe, but can be smeary.
• Setting 2 (Medium): Almost always the best balance. Low ghosting with zero overshoot.
• Setting 3 (Fastest/Extreme): Almost always a marketing trap. It produces horrific inverse ghosting just so the company can claim “1ms” on the box.

Summary: Speed Comparison Table

Understanding the science of response time allows you to ignore the “1ms” marketing hype and tune your monitor for actual clarity. Don’t sacrifice image quality for a number on a box!

Check your monitor’s motion clarity and find the perfect overdrive setting with our Motion Test Tool today!