RTX 4090 Overclocking Guide: Safe Settings and How to Test Stability

Know your normal GPU temperatures before you start, so you can tell when an overclock is running too hot.

The RTX 4090 already runs close to its limit out of the box, so overclocking it is about squeezing out a few percent, not turning it into a different card. That’s still worth doing for some people. This guide covers what to expect, the two safe ways to do it in MSI Afterburner, and how to test that it’s actually stable, including how to tell GPU artifacts from a problem with your screen. Steps come from MSI and NVIDIA support, and the gains from TechPowerUp’s published tests.

RTX 4090 specs that matter for overclocking

All from NVIDIA’s RTX 4090 page. Partner cards ship with their own clocks and power limits, so check the maker’s page for your exact model. In practice the card boosts well past 2.52 GHz on its own when it has thermal and power headroom.

How much faster does an overclocked RTX 4090 get?

Not much. TechPowerUp overclocked eight RTX 4090 cards at their default fan, power and voltage settings. Every one landed between 2,974 and 3,018 MHz average GPU clock, and the Founders Edition gained 4.5% in Unigine Heaven.

Two takeaways. Expensive partner cards didn’t overclock meaningfully better than the Founders Edition in that test. And a few percent rarely changes how a game feels. A game at 100 fps becomes roughly 104 fps.

Our view: on a 4090, undervolting is usually the better deal. You give up little or no speed and get lower power draw, heat and fan noise. MSI’s guide covers both, and so do we below.

Before you overclock: three checks

1. Check the power connector. NVIDIA’s power connector update found that the common factor in melted RTX 4090 connectors was a plug not fully inserted. Push it in firmly and evenly until there’s no gap. Use separate PSU cables for each 8-pin input on the adapter, not one cable with a pigtail, as MSI also recommends.
2. Get MSI Afterburner from msi.com or Guru3D only. MSI warns that phishing sites hand out modified installers that steal data.
3. Run a baseline. Pick a benchmark or a game with a built-in benchmark, run it at stock, and write down the frame rate, GPU clock, memory clock, voltage and temperature.

Update the driver first, too. Our NVIDIA drivers guide covers a clean install.

Method 1: MSI Afterburner OC Scanner

This is the method MSI recommends, and it works on non-MSI cards too. It takes about 30 minutes.

1. In Afterburner Settings, tick Unlock Voltage Control and Unlock Voltage Monitoring, then restart Afterburner.
2. Move the power limit, temperature limit and core voltage sliders to their maximum and click Apply.
3. Open the Curve Editor (Ctrl+F) and click OC Scanner, then Scan.
4. When it finishes, the Core Clock shows Curve. Save it to a couple of profile slots and click Apply.
5. Run a benchmark for 10 minutes and watch for glitches, flicker, black screens or crashes. Then play a demanding game.

Ctrl+D resets the card to defaults at any point. Your saved profiles stay.

Method 2: manual overclock, step by step

1. Max the power and temperature limit sliders and click Apply.
2. Raise Core Clock by 20 to 30 MHz, apply, and run your benchmark. Repeat until you see crashes or glitches, then go back to the last good step.
3. Save that as a profile.
4. Now raise Memory Clock by 50 to 100 MHz per step and test each time. If you see glitches, drop it 10 MHz at a time until it’s clean.
5. Watch the score as well as the screen. If a higher memory clock gives a lower benchmark result, you’ve gone past the useful point. Back off.
6. Run a 10-minute benchmark, then your games. MSI suggests stepping the final core and memory values back a little for long-term stability.

Those step sizes are MSI’s. The process is slow. That’s the point. Big jumps only make it harder to tell which setting broke things.

Undervolting an RTX 4090 instead

Two ways, both from MSI’s guide:

• Power limit slider. Leave voltage at default, then lower Power Limit to somewhere between 70% and 90% in 5% steps, testing as you go. This is the easy one.
• Curve Editor. Flatten the voltage curve at a chosen point (MSI mentions around 950 mV as a typical start) so the card never asks for more. MSI notes the 4090 may be locked in firmware below the graph, so you may need to go lower than expected before you see a change.

We haven’t measured the trade-off on our own card, so test your games. Watch the 1% lows as well as the average frame rate. An unstable undervolt often shows up as stutter before it crashes.

How to tell if your overclock is unstable (and what artifacts look like)

An overclock that’s pushed too far usually shows up as one of these:

• Artifacts: flashing colored dots, checkerboard blocks, stretched polygons or texture flicker that move with the game.
• Stutter and worse 1% lows, even if the average fps looks fine.
• The game crashing to desktop, the driver resetting with a black screen for a second, or the whole PC freezing.

Artifacts from the GPU appear in games under load and move with the scene. A dot that sits in the same spot on the desktop, on every color, at stock clocks, isn’t the GPU at all. That’s your panel. Reset to stock (Ctrl+D) and run our dead pixel test: if the dot is still there on a plain color screen, it’s a screen problem and no clock setting will fix it.

Black screen that won’t come back? Hold the power button for more than 4 seconds to force a shutdown. Afterburner only reapplies settings at startup if you turned on Apply at Windows Startup, so if you did, reset with Ctrl+D as soon as Windows loads.

Temperatures and power under an overclock

NVIDIA lists 90°C as the RTX 4090’s maximum GPU temperature. The card protects itself by pulling clocks down as it gets close, which MSI points out too. So heat doesn’t usually kill a 4090 straight away. It just quietly takes back the overclock you added.

More power also means more strain on the PSU. NVIDIA asks for an 850W system. If an overclock makes your PC shut off under load, that’s often the PSU tripping its protection, not the GPU failing. Our RTX 4090 power supply guide explains sizing, and our high GPU temperature guide covers cooling.

FAQ

Is it safe to overclock an RTX 4090?

Within the limits Afterburner allows, generally yes. The card reduces clocks and voltage as it reaches its limits. The bigger risk on a 4090 is a power connector that isn’t fully seated, so check that first.

How much performance does an RTX 4090 overclock add?

Usually a few percent. TechPowerUp measured 4.5% on the Founders Edition in Unigine Heaven, with eight cards all reaching about 2,974 to 3,018 MHz average clock.

What’s a good memory overclock for an RTX 4090?

There’s no number that works on every card. Raise it in 50 to 100 MHz steps and stop when the benchmark score stops going up or you see glitches.

Should I undervolt or overclock my RTX 4090?

For most people, undervolt. You keep nearly all the speed and cut power, heat and noise. Overclock if you want the last few percent and your cooling can take it.

How do I reset my GPU overclock?

In MSI Afterburner, press Ctrl+D or click the reset icon. Your saved profiles aren’t deleted.

Sources

We haven’t overclocked an RTX 4090 ourselves for this guide. Steps come from MSI’s Afterburner guide and NVIDIA support, and the overclock results from TechPowerUp’s published tests, all linked here.

• NVIDIA: GeForce RTX 4090 specifications, checked 2026-10-27.
• TechPowerUp: RTX 4090 Founders Edition review, overclocking and power limits (Oct 2022), checked 2026-10-27.
• MSI: Afterburner overclocking and undervolting guide (Sep 2023), checked 2026-10-27.
• NVIDIA: Power connector update, GeForce RTX 4090 (Nov 2022), checked 2026-10-27.