Improving Nvidia RTX 4090 GPU Efficiency Through Power Limiting

4090 GPU

Nvidia GeForce RTX 4090 GPU delivers unprecedented performance and ranks at the top in our GPU benchmarks hierarchy. It is also the fastest graphics card. It’s not the most efficient GPU, but this is mostly due to design choices. Through power limiting, we can increase efficiency and possibly reduce the risk of melting power adapters. This is basically an alternative to underclocking or undervolting. It’s also the opposite to overclocking.

To test the RTX 4090 GPU Founders Version of Nvidia, we have run eight of our most difficult tests on it to determine its performance, clock speeds, temperatures and power requirements. We tested in 10% increments. We began at 120%, and then dropped to just 50% to give you all the options.

Before we move on to the test results, please note that higher power limits won’t improve performance if the GPU clock speed is not increased. We tested RTX 4090 GPU overclocking elsewhere. In our standard gaming test suite we found that overclocking only 4% increased the RTX 4090’s performance, even at 4K Ultra settings. However, in our DXR (DirectX Raytracing), overclocking proved to be a bit more useful and increased performance overall by approximately 9%.

Read More: Nvidia GeForce RTX 4090 GPU Review

The more demanding the game at any setting we test it with, the greater the impact of changing the power limit. There are many games, however, that don’t strain a GPU like a RTX 4090, even at maximum settings of 4K or maxed out Microsoft Flight Simulator, for example, is a game that doesn’t do this because of its CPU-limited nature. Although such games run faster at lower power limits than the RTX 4090 GPU, it’s not because the GPU was exceeding its 450W total board power limit.

RTX 4090 GPU Power Limiting Test Setup

Our Core i9-12900K test computer is being used. Although we would probably increase the power consumption of the graphics card if it were to be upgraded to the Core i9-13900K model, this is unlikely to cause any significant changes. Our DXR test suite is being used for power-limited testing. We have also added A Plague Tale: Requiem to our DXR toolkit, which supports DLSS3. To test the efficacy and performance of DLSS2 or DLSS3, we wanted at least one set of tests to be included. We tested both.

Other games that we test are Bright Memory Infinite Benchmark, Control Ultimate Edition and Cyberpunk 2077. Cyberpunk doesn’t have “Psycho” lighting, so we use the highest quality setting. Also, we enabled HairWorks in Metro Exodus Enhanced and Advanced PhysX in Cyberpunk. This is slightly different from the previous Metro Exodus Enhanced testing. These results are not to be compared with other reviews, which may have used slightly different settings.

We’ve again run the eight above gaming tests with eight power limits for the RTX 4090 GPU Founders edition. We also tested at 110%, 120%, and 100% to determine if increasing the power limit would improve performance. To improve power efficiency, we tested the power limit at 90%, 80% and 70%.

All performance data is captured using the Nvidia Frame View utility. This utility also records GPU clock speeds, temperatures and power consumption data. Although the reported power consumption is not exactly the same as the real-world power usage measured with external tools such as Powenetics (which can be found in the FrameView utility), the results show that Nvidia’s software reports figures within 10W of what was measured using Powenetics. We are able to gather a lot more data faster.

RTX 4090 GPU Overall Power Efficiency

The GDDR6X clocked clocks were not adjusted. As such, it is possible that the memory could use a smaller portion of the overall power budget. The overall results are shown below, with equal weighting to all scores.

It is evident that there is almost no performance change by increasing the power limit or decreasing it by 10%. Frame rates also drop by 2.3% when the power limit is increased to 80%. This is noticeable but not meaningful. Even with a 70% limit, performance is only 5% slower then stock. This drops to 10% faster at 60% and 23% slower for 50%.

Each power-limited configuration has a higher power efficiency rating than the stock settings. Performance per watt at 4K was 0.175 FPS/W, while the most demanding games were 0.066 FPS/W. Power Efficiency drops at 110% to 0.169 FPS/W while it drops to 120% to 0.166 FPS/W. The opposite direction shows that power efficiency increases to 0.179 when 90%, 0.214 at 70% and 0.222 at 60% respectively, and then to 0.237 at 50%.

It’s also “better across all power limits. Gains are now evidently declining at 50%. However, pure performance still matters. Most people don’t want to spend $1,600 on a graphics card that limits performance and improves efficiency. You can reduce your power consumption if you’re concerned about the adapter breaking and wait for a replacement.

gpu efficiency

Our average power usage across our eight games tests was 402.3W at standard, which rose to 428.3W as we increased the power limit to 120%. However, a theoretical 20% increase in power limit caused a 6.5% increase in real-world power use due to other system bottlenecks. What’s more, the power limit limits can cause a drop in power consumption, clocks, or temperature. At 80% (which seems to be a sweet spot on efficiency curve), the average power use is 353W. This is similar to what you would see with an RTX3090 and 3080 Ti. GPU temperature dropped a little bit and the clock speed averaged 2,611MHz.

The power limit of 50% meant that the average power draw was only about 224W. GPU temperature was just 53C. Core clocks are now at 1,644MHz. While performance would be comparable with the RTX 3090 Ti’s, we’d still prefer to increase the power limit by 60% or 70%.

Bright Memory infinite Benchmark Power Efficiency

The Bright Memory Infinite testing results were very similar to those in the overall chart. Performance is not affected by clock speeds exceeding their limits. A power limit reduction of 80% by 355W (instead of 415W) reduces power usage by 14%, while performance is only reduced by 3%.

The stock reference RTX 4090 GPU Founders’ Edition has a power draw of well over 400W. However, it’s far below the 450W max TBP. There are reports that the RTX 4090 “only consumes about 350W while gaming”, but these are not universal truths. GPU power use will decrease significantly in CPU-limited settings, but it will be much higher for most games, particularly raytracing, where you’ll get more than 400W at Ultra 4K settings.

Control Ultimate Edition was one of our most demanding games, at least in terms of power consumption. The stock 4090FE was consuming 424W of electricity or 26W below the TBP. This means it will be more susceptible to power limit changes than other games.

In practice, Bright Memory Infinite doesn’t make things any different. The power draw at 80% drops from 357W to 357W, representing a 17% drop, while performance drops by 2.1%. The difference might be greater in longer gaming sessions since time constraints made it difficult to test the system for more than a few seconds per game. But clearly, the 4090 GPU doesn’t aim at maximum efficiency.

Cyberpunk2077 is well-known for being one the most challenging games. It also used less power than some other games in our tests. We measured 413W power usage at 100%. That dropped to 351W for 80%.

70% or 80% seems to be the optimal balance of power and performance. At 80%, you get 96% performance with 85% power usage, while at 70%, you get 94% performance with 75% power. (You don’t use 70%, 80% or all of the base power. The power limit comes from the 450WTBP.

Fortnite (DXR) Power Efficiency

Fortnite, even when using the maximum-out ray tracing settings without DLSS, is one of our most demanding games. And if you are running without a ray tracing effect, it will have lower power requirements. 

The RTX 4090 GPU is only 375W in stock. Even at a 120% maximum power limit, it still only uses 407W. Even though performance is reduced by lowering the power limit, it may not result in as much power savings. Both the 90% power limit and 80% power limit deliver similar performance with a power usage of 368W or 346W respectively. The 70% limit decreases power consumption to only 309W. This is an 18% drop in power compared with stock. However, performance drops 9%. Based on our testing Fortnite is best at 60%. You get 91% of the base performance while using 29% less electricity.

Metro Exodus Enhanced Edition Power Efficiency

Surprisingly, Metro Exodus Enhanced Edition was the most challenging game in our test suite. The Extreme preset is used, but Advanced PhysX and HairWorks are also enabled. The RTX 4090 GPU consumes 432W even at its stock settings. This jumps up to 465W with an 11% power limit and 483W when there is a 120% limit. 

This is quite remarkable considering that none of the other games managed to exceed 450W at the 120% setting. The performance gains at higher power limits are still minimal, with 1.2% and 1.8% respectively. Based on the baseline measurements, a decrease in the power limit will result in a smaller drop in performance. Performance drops by 5% and actual power consumption drop by 18% at 80% power limits. Performance is affected by each additional 10% power drop, but 70% still delivers 92% of the base FPS. Performance drops at the last two power limits, which is why power efficiency at 50% is worse than at 60%.

power efficiency

Although Minecraft can be run without ray-tracing, it is not possible to run it on a potato. However, DXR enabled makes it quite difficult. The RTX 4090 GPU uses full path tracing to create shadow effects, lighting, and reflections. However, the base power consumption is only 380W. This is similar to Fortnite in that we don’t see any performance impacts from limiting power as in other games.

The Founders Edition RTX 4090 GPU Founders Edition has a 60% setting, which reduces power consumption by 30% and only decreases performance by 8%. Although the 50% setting is technically better than the 50% setting, the 10% power reduction causes an additional 11% drop in performance.

A Plague Tale: Requiem Power Efficiency

A Plague Tale: Requiem was the only game we tested with DLSS 2 (Frame Generation), and DLSS 3 (“Frame Generation”) to see how that impacts power consumption. Frame Generation, although it increases latency and reduces GPU load, should in theory lower the GPU load. This is exactly what we observed in our testing.

In Quality mode with DLSS 2 super scaling enabled, the power consumption at stock settings of 398W is achieved. This is slightly less than other games, but it’s still not the lowest we tested. DLSS 3 lowers that to 387W. It also breaks the 144 fps mark.

Framerates are maintained above 144 fps when the 80% power limit is reached and then fall below 70% at 70%. This means that you lose only 1% and 4% respectively of your base performance. The lower starting point doesn’t cause power consumption to drop as much: it is only 8% down on the 80% setting, and 19% on 70%. DLSS 2 had a slightly higher performance and power impact, but it’s not worth mentioning.

Nvidia RTX 4090 GPU Power Efficiency: Closing Thoughts

Nvidia’s GPUs are designed to find the ideal voltage-frequency curve spot for maximum power efficiency. However, desktops are often driven by the desire to achieve maximum performance while preserving efficiency. To achieve the final 5% performance, you will need 15-20% more power.

Users have reported issues with the 16-pin power adapter. Anyone who has an RTX 4090 GPU and still uses it might consider reducing their power consumption. They can also remove the side panel from the case and try to not put any stress on the connector. Although it doesn’t mean the connector will not melt, it can make it less likely while we wait for the manufacturer to recall the adapter.

power efficient gpu

Nvidia’s bright side is that the actual cost for the adapter cable is relatively low compared to an RTX 4090 graphics card. The other bright side for users is that you can increase overall efficiency by 20-30% if your GPU has a 70% or 60% power limit but it will also decrease performance on your new, not yet melted extreme GPU.

Other GPU cards may also produce results that are different from the ones we have shown. Overclocked factory models run at higher voltages and are not as efficient at lower power limits. Nevertheless, the process we used was straightforward. You only need a utility such as MSI afterburner to set a power limit.

We are eager to see AMD’s reaction to the 4090 GPU melt adapter scandal. While we know AMD won’t be using the 16-pin 12VHPWR Connector on its upcoming GPUs, AMD has been drumming up efficiency over the past few generations. RDNA 3 might be a lot more efficient than Ada Lovelace, provided you stay with Nvidia’s default power settings. But, will it be faster? We will have to wait and see.

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