The AMD Ryzen 9 7940HS and AMD Ryzen 7 7840HS are both AMD Ryzen 7040 series processors released in the first quarter of 2023. The former belongs to the Ryzen 9 series, and the latter belongs to the Ryzen 7 series. While Ryzen 9 is designed to deliver higher performance, the two processors actually have almost identical specifications: both incorporate 8 Zen 4 CPU cores, 16 threads, 16MB L3 cache, and 8MB L2 cache. They are also the first two processors to feature an RDNA 3 iGPU.

The integrated graphics card found in the 7840HS and 7940HS processors is called Radeon 780M, which incorporates 12 RDNA3 GPU cores as well as a video engine with AV1 de- and encoding support. Currently, the Radeon 780M is the fastest iGPU in the market.

Let's look at the key differences between the Ryzen 9 7940HS and Ryzen 7 7840HS. 

In terms of CPU specifications, the 7940HS is 0.2GHz higher than 7840HS in base frequency, and only 0.1GHz higher in max boost frequency. On the graphics front, the two chips feature the same exact iGPU, with the same number of execution units. The only difference on paper is the 0.1GHz gap in GPU frequency.

From the sheet above, we can see clearly that 7940HS and 7840HS are identical in key specifications, but how about their performance？

We have run numerous benchmark tests on the two processors at different TDPs.

65W 7840HS VS 65W 7940HS

Conclusion: According to the test results, the two chips were returned identical scores in CPU-Z single-core test. In GeekBench 5, The 7940HS scored just 1% higher than the 7840HS in CPU single-core performance, and 3% in multi-core performance. The differences are quite small.

Next, let's take a glance at the benchmark results of 65W 7840HS and 54W 7940HS. 

65W 7840HS VS 54W 7940HS

Conclusion: In the CPU-Z single-core test, the 7940HS (54W) scored 5.7 points higher than the 7840HS (65w), the gap is less than 1%. In Geekbench 5 CPU single-core test, the 7940HS (54W) scored only 6 more points than the 7840HS (65W), but the gap is only 0.3%.

However, the 7840HS (65W) handily beats the 7940HS (54W) in terms of multi-core performance, as the former scored 82 more points in CPU-Z multi-core test, 11 more points in GeekBench 5 CPU multi-core test, and most surprisingly, 195 more points in CineBench R20.

*CineBench R20 evaluates the CPU performance of a computer by rendering a complex 3D image with only the CPU cores.

As the numbers indicate, the Ryzen 7 7840HS, with its TDP configured at 65W, could perform significantly better than the Ryzen 9 7940HS at 54W.

Finally, let's look at the benchmark comparison of the Ryzen 7 7840HS (65W) and Ryzen 9 7940HS (45W). 

65W 7840HS VS 45W 7940HS

Conclusion: The 7840HS (45W) outperformed the 7940HS (45W) in nearly every benchmark, the gap in Cinebench R20 was even larger than 10%!

Some folks find it difficult to make a choice between the 7840HS and the 7940HS. Our recommendation is that you should compare the differences in both performance and price. There is no point in paying more on a PC with a 7940HS chip configured at 45W or 54W when you can get more performance out of a cheaper PC with a 65W 7840HS processor.

Based on the test results listed above, it is clear that increasing the TDP will have a huge positive impact on unleashing the performance of high-end processor.

In short, Ryzen 9 7940HS and Ryzen 7 7840HS are both excellent processors that pack enormous horsepower. However, it is important for you to consider your budget and your needs when choosing one chip over the other. Furthermore, it’s also necessary to give some thoughts to heat dissipation, as top processors need top cooling technology to achieve the best performance possible, and some products definitely do better than others in this area.