RTX 4090 Efficiency Through Power Limiting

Improving Nvidia RTX 4090 Efficiency Through Power Limiting

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The Nvidia GeForce RTX 4090 delivers new levels of performance, lands at the top of our GPU benchmarks hierarchy, and is the fastest of the best graphics cards. For all that, it’s not the most efficient of GPUs, but that’s mostly due to design decisions. We can improve efficiency — and potentially reduce the risk of melting 4090 power adapters — through power limiting. This is basically a quick and easy alternative to underclocking and undervolting, and the opposite of overclocking.

For our testing, we’ve taken Nvidia’s RTX 4090 Founders Edition and run it through eight of our most demanding tests to see what happens to performance, clock speeds, temperatures, and power requirements at the various settings. We tested in 10% increments, starting at 120% and dropping down to just 50% to provide the full range of options.

Before we get to the results of our testing, note that without increasing the GPU clock speed, the higher power limits don’t really do much for performance. We’ve tested RTX 4090 overclocking elsewhere and found that in our standard gaming test suite, even at 4K ultra settings, overclocking only increased performance on the RTX 4090 by about 4%. In our more demanding DXR (DirectX Raytracing) test suite, however, overclocking proved a bit more helpful and increased performance by about 9% overall.

In short, the more demanding a game happens to be at whatever settings we test with, the more impact we’ll see from changing the power limit. Conversely, there are a lot of games that don’t tax a GPU like the RTX 4090 much at all, even at 4K and maxed-out settings — Microsoft Flight Simulator is a perfect example of this, given its CPU-limited nature. Such games may run just as fast at lower power limits, but that’s because the GPU wasn’t hitting its 450W TBP (Total Board Power) limit to begin with.

RTX 4090 Power Limiting Test Setup

We’re using our existing Core i9-12900K test PC. We would likely increase power consumption from the graphics card if we were to upgrade to the new Core i9-13900K, but probably not by too much. We’re using our DXR test suite for the power-limited testing, with the addition of A Plague Tale: Requiem, a recent release that also happens to support DLSS3. We wanted to include at least one set of tests using DLSS2 and DLSS3 (we tested both) to see what that did for performance and efficiency.

The other games we use for testing are Bright Memory Infinite Benchmark (far more impressive looking and demanding than the actual game), Control Ultimate Edition, Cyberpunk 2077, Fortnite, Metro Exodus Enhanced Edition, and Minecraft. We mostly use the maximum quality setting with all ray tracing options enabled, without DLSS of any form, though we didn’t enable “Psycho” lighting in Cyberpunk. Note also that we enabled HairWorks and Advanced PhysX in Metro Exodus Enhanced, which is slightly more demanding than the previous testing we’ve conducted using that game. In other words, these results should only be compared within this article, as other reviews may have used slightly different settings.

Again, we’ve run all eight of the above gaming tests at eight different power limits on the RTX 4090 Founders Edition. Besides the default 100% limit, we tested at 110% and 120% to see if simply increasing the power limit would help performance. Then we also tested at 90%, 80%, 70%, 60%, and 50% to try and improve efficiency.

We capture all performance data using Nvidia’s FrameView utility, which also collects GPU clock speeds, temperatures, and power consumption data. While the power consumption reported by the software isn’t exactly the same as real-world power use measured using external tools like Powenetics, looking at the results indicates that Nvidia’s software reports figures that are within about 10W of what we measured using Powenetics, with the added benefit being that we’re able to collect a bunch of data much more quickly.

With that preamble out of the way, let’s hit the test results. 

RTX 4090 Overall Power Efficiency

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