AMD Ryzen 7 7840U vs AMD Ryzen 9 5900HX Comparison

Head-to-Head Benchmarks

The benchmark comparison between the AMD Ryzen 9 5900HX and the AMD Ryzen 7 7840U reveals a clear split: the older Zen 3 chip leads in multi-threaded 3DMark tests, while the newer Zen 4 part dominates nearly every other category. Across 23 recorded benchmarks, the Ryzen 7 7840U claims 16 wins, leaving the Ryzen 9 5900HX with 7 victories.

The Ryzen 9 5900HX secures its largest advantages in the 3DMark suite. In the 16-thread test, it scores 6490 versus 5427, a 19.6% lead. The margin grows to 20.1% in the max-threads test, with scores of 6487 and 5402 respectively. The 8-thread test shows an 18% gap, 5406 against 4583, while the 4-thread test delivers a 8.5% advantage, 3285 versus 3029. These results indicate that the 5900HX sustains higher throughput when all cores are engaged, a pattern consistent with its higher TDP envelope of 45 watts against the 28 watts of the 7840U.

The Ryzen 7 7840U answers with decisive single-thread performance. The Geekbench single-core score shows a 13.7% margin, 2077 versus 1792. Cinebench R23 single-core widens this to 11.3%, with 1677.5 against 1488. The single-thread 3DMark test favors the 7840U by 5.5%, 932 versus 881, and Cinebench R15 single-core shows a 9.1% gap, 264 against 240. The PassMark single-thread result repeats the pattern, 3565 versus 3178, a 10.9% delta. These numbers point to a substantially higher per-core efficiency in the Zen 4 architecture.

The 7840U also leads across computational workloads. PassMark physics shows a 27.6% advantage, 1256 versus 909, which is the largest single delta in the entire comparison. Prime number finding follows at 33.7% ahead, 80 versus 53, though the absolute scores are low for both parts. Floating-point math favors the 7840U by 8.1%, 51767 against 47556, and integer math by 4.5%, 90852 versus 86735. Extended instructions land at 4.6% ahead, 20432 versus 19488, while random string sorting shows an 11% gain, 33757 against 30042. Multithread PassMark, which is a broader measure of parallel work, gives the 7840U a 9.9% edge, 24782 versus 22326.

Some tests are nearly tied. Cinebench R23 multi-core shows only a 1% difference, 12845 for the 5900HX against 12719 for the 7840U. Geekbench multi-core is within 0.5%, 8766 versus 8720. Data compression differs by just 0.3%, 288604 against 287793. The 2-thread 3DMark test is essentially even, 1729 versus 1720, a 0.5% margin. The 5900HX holds a 2.8% edge in data encryption, 18188 versus 17691, and a 5.8% lead in Cinebench R15 multi-core, 2106 against 1990.

The average benchmark score reinforces the overall picture: the 7840U averages 25432, while the 5900HX averages 24822. Both parts occupy the 77th percentile among all CPUs, meaning they sit at the same rank despite the 7840U posting a roughly 2.5% higher aggregate score. The nearest rivals for each part confirm their positioning. The 5900HX trades blows with the Intel Core 5 210H, which averages 24872, and the Intel Core i7-13620H at 24911, with deltas of -0.2% and -0.4%. The 7840U matches the Intel Core i7-11700KF exactly at 25423, while trailing the AMD Ryzen 7 5825U by 0.1% and the AMD Ryzen 5 7640U by 0.2%.

Architecture Differences

The two processors come from different manufacturing generations, which explains the benchmark split. The Ryzen 9 5900HX belongs to the 5000 series, built on the Zen 3 architecture with the Cezanne codename. It uses a 7 nm process at TSMC, packing 10,700 million transistors into a 180 mm² die. The Ryzen 7 7840U is from the 7000 series, using the Zen 4 architecture with the Phoenix codename. It is manufactured on a 4 nm process at TSMC, with 25,000 million transistors on a 178 mm² die. The newer node allows the 7840U to deliver higher clock speeds and better efficiency despite a lower TDP.

Both chips have 8 cores and 16 threads, so the core count is identical. The L1 cache is the same at 64 KB per core, and the L3 cache is also the same at 16 MB shared. The L2 cache differs: the 5900HX has 512 KB per core, while the 7840U doubles that to 1 MB per core. This larger L2 allocation contributes to the 7840U's advantage in single-threaded and latency-sensitive workloads.

Clock speeds diverge significantly. The 5900HX runs a base clock of 3.30 GHz and a boost clock of 4.60 GHz. The 7840U matches the base clock at 3.30 GHz but boosts to 5.10 GHz, a 0.50 GHz higher ceiling. The TDP rating also differs, with the 5900HX rated at 45 watts and the 7840U at 28 watts. The lower power draw of the 7840U, combined with a higher boost clock, indicates a substantial improvement in performance per watt.

Memory support marks another generational shift. The 5900HX uses DDR4 memory with dual-channel support and a bandwidth of 68.3 GB/s. The 7840U moves to DDR5, also dual-channel, with bandwidth of 89.6 GB/s. That is a 31% increase in theoretical memory bandwidth, which benefits the 7840U in memory-heavy workloads. ECC memory is not supported on the 5900HX but is supported on the 7840U. PCIe connectivity also advances: the 5900HX is limited to Gen 3, while the 7840U offers Gen 4 with 20 lanes on the CPU.

Integrated graphics differ as well. The 5900HX pairs with Radeon Vega 8, while the 7840U features Radeon 780M. The newer Radeon 780M benefits from the Zen 4 platform's improvements, though the database does not record separate GPU benchmark scores for either part.

The sockets are incompatible. The 5900HX uses AMD Socket FP6, while the 7840U uses AMD Socket FP8. The multiplier is unlocked on the 5900HX but locked on the 7840U, so enthusiasts have more overclocking headroom with the older chip. The 5900HX has a release date of January 11, 2021, while the database lists no release date for the 7840U. Both parts remain in active production.

FAQ

Q: Which processor has the higher boost clock?

A: The AMD Ryzen 7 7840U boosts to 5.10 GHz, while the AMD Ryzen 9 5900HX reaches 4.60 GHz. The base clocks are identical at 3.30 GHz.

Q: How do the two chips compare in single-thread performance?

A: The 7840U leads in every single-thread test. Geekbench single-core shows 2077 versus 1792, a 13.7% margin. Cinebench R23 single-core gives 1677.5 against 1488, an 11.3% gap. PassMark single-thread records 3565 versus 3178, a 10.9% delta.

Q: Where does the Ryzen 9 5900HX hold its advantage?

A: The 5900HX wins all 3DMark multi-thread tests. It leads by 19.6% in 16-thread, 20.1% in max-threads, 18% in 8-thread, and 8.5% in 4-thread. It also edges out the 7840U in data encryption by 2.8% and Cinebench R15 multi-core by 5.8%.

Q: What is the memory bandwidth difference?

A: The 7840U supports DDR5 with 89.6 GB/s bandwidth, while the 5900HX supports DDR4 with 68.3 GB/s. Both use dual-channel memory buses.

Q: Are the core counts the same?

A: Yes, both processors have 8 cores and 16 threads. The L1 cache is identical at 64 KB per core, and the L3 cache is 16 MB shared on both. The L2 cache differs, with 512 KB per core on the 5900HX and 1 MB per core on the 7840U.

Q: Which chip has more transistors?

A: The 7840U contains 25,000 million transistors on a 178 mm² die, while the 5900HX contains 10,700 million transistors on a 180 mm² die. The 7840U also uses a smaller 4 nm process compared to the 5900HX's 7 nm process.

Specification Differences

The database records several fields where the two processors differ. The process node is 7 nm for the 5900HX and 4 nm for the 7840U. Transistor count is 10,700 million versus 25,000 million. Die size is 180 mm² against 178 mm². Boost clock is 4.60 GHz versus 5.10 GHz. TDP is 45 watts versus 28 watts. L2 cache is 512 KB per core versus 1 MB per core. Memory support is DDR4 versus DDR5. Memory bandwidth is 68.3 GB/s versus 89.6 GB/s. ECC memory is false versus true. PCIe is Gen 3 versus Gen 4 with 20 lanes. Integrated graphics is Radeon Vega 8 versus Radeon 780M. Socket is AMD Socket FP6 versus AMD Socket FP8. The multiplier is unlocked on the 5900HX but locked on the 7840U. Part numbers are 100-000000300 for the 5900HX and 100-000000829100-000000830100-000001131 for the 7840U. The release date is January 11, 2021 for the 5900HX, while the database has no release date for the 7840U.

The Verdict

The data directs each processor toward a different use case. The AMD Ryzen 9 5900HX is the stronger choice for workloads that fully utilize all 8 cores and 16 threads, particularly when sustained multi-threaded throughput matters. Its 3DMark results, with leads of 19.6% in 16-thread and 20.1% in max-threads, show that it can maintain high performance across all cores, likely because of its higher 45-watt TDP. Users running parallel rendering, compilation, or other all-core tasks would see tangible gains from the 5900HX, and its unlocked multiplier offers additional tuning freedom.

The AMD Ryzen 7 7840U is the better pick for almost everything else. Its single-thread dominance, ranging from 5.5% to 13.7% across different tests, makes it the superior choice for everyday responsiveness, office productivity, and lightly threaded applications. The 27.6% lead in PassMark physics and 33.7% lead in prime number finding indicate strong per-core computational efficiency. The 89.6 GB/s memory bandwidth from DDR5 support, double the L2 cache, and a 5.10 GHz boost clock all contribute to its higher average benchmark score of 25432 against 24822.

The 28-watt TDP of the 7840U also suggests better efficiency for thin-and-light laptops, where thermals and battery life take priority over raw multi-thread grunt. The 5900HX, with its 45-watt rating and older 7 nm process, would fit more naturally into larger chassis with robust cooling. Both parts sit at the 77th percentile among all CPUs, so neither is a weak performer; the choice comes down to whether the workload favors the 5900HX's all-core stamina or the 7840U's single-thread speed and modern platform features. Given that the 7840U wins 16 of 23 benchmarks and posts the higher aggregate score, it is the more versatile processor for general usage, while the 5900HX remains specialized for multi-threaded 3DMark-style scenarios.