AMD Ryzen Embedded 8840U vs AMD Ryzen Embedded 9900X Comparison

Head-to-Head Benchmarks

The database does not contain any recorded benchmark scores for either the AMD Ryzen Embedded 8840U or the AMD Ryzen Embedded 9900X. Both processors have an empty benchmark results array, meaning there are no direct head-to-head performance measurements available for comparison. The recorded data shows zero wins for each processor in direct competition, and neither has an average benchmark score assigned. The percentileVsAllCpus field places both at the 50th percentile, which indicates a mid-pack position relative to all CPUs in the database, but this value carries no performance weight without actual scores behind it.

Since no synthetic or application-specific benchmark numbers exist for these two parts, a direct numerical comparison of their performance is impossible from the available data. What can be stated with certainty is that the 8840U carries 8 cores and 16 threads, while the 9900X carries 12 cores and 24 threads. The 9900X also posts a higher base clock of 4.40 GHz versus 3.30 GHz on the 8840U, and a higher boost clock of 5.60 GHz versus 5.10 GHz. These specifications suggest the 9900X should deliver higher peak throughput in multi-threaded workloads, but without recorded benchmark results, the database cannot confirm the magnitude of any such advantage.

The absence of benchmark data means the head-to-head section must rely on specification-level indicators rather than measured outcomes. The 9900X has 50% more cores and 50% more threads than the 8840U, which typically translates into proportionally higher multi-threaded performance in scalable workloads. Single-thread performance is harder to project, though the higher boost clock on the 9900X gives it a nominal advantage in clock-sensitive tasks. The 8840U's lower clocks and smaller core count place it at a clear specification disadvantage in raw compute terms, but its 28-watt TDP positions it as a far more power-efficient option.

Where Each One Wins

The use-case split between these two processors is defined primarily by their thermal and physical design targets. The 8840U is classified in the database as a Mobile segment part, with a 28-watt TDP and an AMD Socket FP8. This combination makes it suitable for compact, power-constrained systems such as thin-and-light laptops, mini PCs, and fanless or low-noise embedded devices. The 9900X is a Desktop segment part with a 120-watt TDP and an AMD Socket AM5, which points toward larger chassis with active cooling and higher power delivery capacity.

For workloads that scale with core count and clock speed, the 9900X holds the specification advantage. Its 12 cores, 24 threads, 4.40 GHz base clock, and 5.60 GHz boost clock give it a clear lead in rendering, compilation, scientific computing, and other heavily threaded tasks. The larger L3 cache of 64 MB versus 16 MB on the 8840U also benefits data-intensive workloads that repeatedly access a working set larger than the smaller cache can hold.

For power-sensitive and thermally constrained applications, the 8840U wins by default. Its 28-watt TDP is less than a quarter of the 9900X's 120-watt TDP, allowing it to operate in systems where the 9900X would require substantial cooling infrastructure. The 8840U also integrates the Radeon 780M graphics solution, whereas the 9900X only carries a basic Radeon Graphics implementation. In embedded or mobile systems that need basic display output without a discrete GPU, the 8840U provides a more complete package.

The 8840U uses PCIe Gen 4 with 20 lanes, while the 9900X uses PCIe Gen 5 with 24 lanes. For systems that rely on a single high-bandwidth device such as a GPU or NVMe drive, the 9900X's newer PCIe standard offers twice the per-lane bandwidth. For systems with multiple lower-bandwidth peripherals, the 8840U's 20 lanes may still be sufficient, but the 9900X provides more headroom for expansion.

FAQ

Q: Which processor has more cores and threads?

A: The AMD Ryzen Embedded 9900X has 12 cores and 24 threads. The AMD Ryzen Embedded 8840U has 8 cores and 16 threads.

Q: What are the clock speed differences between the two?

A: The 8840U has a base clock of 3.30 GHz and a boost clock of 5.10 GHz. The 9900X has a base clock of 4.40 GHz and a boost clock of 5.60 GHz.

Q: How do their thermal design power ratings compare?

A: The 8840U has a TDP of 28 watts. The 9900X has a TDP of 120 watts.

Q: Do both processors support ECC memory?

A: Yes, both the 8840U and the 9900X have ECC memory support enabled in the database.

Q: What memory bandwidth do they support?

A: Both processors support dual-channel DDR5 memory with a bandwidth of 89.6 GB/s.

Q: Which processor supports PCIe Gen 5?

A: The 9900X supports PCIe Gen 5 with 24 lanes. The 8840U supports PCIe Gen 4 with 20 lanes.

Specification Differences

The two processors differ across nearly every major specification field. The 8840U uses 8 cores and 16 threads, while the 9900X uses 12 cores and 24 threads. Base clock is 3.30 GHz on the 8840U versus 4.40 GHz on the 9900X. Boost clock is 5.10 GHz on the 8840U versus 5.60 GHz on the 9900X. TDP is 28 watts for the 8840U and 120 watts for the 9900X.

Socket types differ as well: the 8840U uses AMD Socket FP8, while the 9900X uses AMD Socket AM5. The 8840U is classified as a Mobile market segment part, and the 9900X is classified as Desktop. The 8840U has a multiplier that is locked, while the 9900X has an unlocked multiplier, enabling overclocking. The 8840U has a part number listed as unknown; the 9900X has part number 100-000000662E.

Both processors support DDR5 memory on a dual-channel bus with 89.6 GB/s of bandwidth, and both have ECC memory support enabled. The cache layouts differ: the 8840U has 64 KB of L1 per core and 1 MB of L2 per core with 16 MB of shared L3. The 9900X has 80 KB of L1 per core and 1 MB of L2 per core with 64 MB of L3.

The 8840U ships with a Radeon 780M integrated graphics solution, while the 9900X ships with a basic Radeon Graphics implementation. The 8840U has a release date of April 1, 2024, and the 9900X has a release date of October 6, 2025. Both are listed as Active in production status. Neither has a launch MSRP recorded in the database.

Architecture Differences

The 8840U is built on the Zen 4 architecture with the codename Hawk Point and belongs to the 8000 series. The 9900X is built on the Zen 5 architecture with the codename Granite Ridge and belongs to the 9000 series. Both use a 4 nm process node from TSMC, but the transistor counts differ substantially: the 8840U has 25,000 million transistors on a die size of 178 mm², while the 9900X has 16,630 million transistors across a dual-die configuration with each die at 70.6 mm².

The 8840U uses a monolithic die design, while the 9900X uses a chiplet design with two CCDs. This explains the 9900X's larger 64 MB L3 cache, which is split across the two dies, versus the 8840U's 16 MB shared L3 on a single die. The L1 cache per core is larger on the 9900X at 80 KB versus 64 KB on the 8840U. L2 cache is identical at 1 MB per core for both.

The 8840U's integrated graphics solution is the Radeon 780M, which is a higher-tier iGPU typical of the Hawk Point platform. The 9900X carries a basic Radeon Graphics implementation, consistent with Granite Ridge desktop parts that expect a discrete GPU in most systems. The 8840U uses PCIe Gen 4 with 20 CPU lanes, while the 9900X uses PCIe Gen 5 with 24 CPU lanes.

Both processors are fabricated by TSMC on a 4 nm node, but the transistor density differs due to the die layout. The 8840U packs 25,000 million transistors into a single 178 mm² die, while the 9900X spreads 16,630 million transistors across two 70.6 mm² dies for a combined 141.2 mm². The 9900X's lower total transistor count despite a newer architecture reflects the chiplet design's exclusion of integrated graphics and other platform elements that the 8840U includes on its monolithic die.

The Verdict

The data points to two distinct roles. The AMD Ryzen Embedded 8840U is a power-efficient mobile processor with 8 cores, 16 threads, a 28-watt TDP, and an integrated Radeon 780M. It fits systems where power draw, heat output, and physical space are primary constraints. Its 5.10 GHz boost clock is respectable for its class, and its 16 MB L3 cache is adequate for moderate workloads. The mobile segment classification and FP8 socket confirm its intended use in compact embedded platforms.

The AMD Ryzen Embedded 9900X is a high-core-count desktop processor with 12 cores, 24 threads, a 120-watt TDP, and an unlocked multiplier. It delivers substantially higher clock speeds at 4.40 GHz base and 5.60 GHz boost, along with a 64 MB L3 cache that benefits large working sets. The AM5 socket, desktop segment classification, and PCIe Gen 5 support position it for systems that prioritize compute throughput over power efficiency.

For a builder selecting between these two, the decision rests on the system's power budget and performance requirements. The 8840U is the choice for fanless or low-power embedded designs, mobile workstations, or compact appliances where the 28-watt TDP is a hard limit. The 9900X is the choice for a desktop-class embedded system with active cooling, where the 120-watt TDP is acceptable and the extra cores, threads, cache, and clock speed are needed for demanding multi-threaded workloads. The database shows no benchmark scores for either part, so the selection must be made on the measured specifications alone: the 9900X dominates in core count, thread count, clock speed, cache size, and PCIe bandwidth, while the 8840U dominates in power efficiency, integrated graphics capability, and physical compactness.