AMD Ryzen 9 PRO 9945 vs AMD Ryzen 9 PRO 9955 Comparison

The Verdict

The AMD Ryzen 9 PRO 9955 and AMD Ryzen 9 PRO 9945 share the same 12-core, 24-thread Zen 5 (Granite Ridge) architecture on TSMC's 4 nm node, but the benchmark database separates them clearly by power envelope and sustained performance. The Ryzen 9 PRO 9955 wins 9 of 11 head-to-head tests, with an average benchmark score of 110,612 versus 96,083 for the Ryzen 9 PRO 9945. That is a 15.1% overall advantage, driven almost entirely by the 9955's 120 W TDP compared to the 9945's 65 W TDP, despite identical base clocks of 3.40 GHz and boost clocks of 5.40 GHz.

The Ryzen 9 PRO 9955 is the straightforward choice for workloads that can stretch across all cores and sustain heavy load for long periods. Its multithread score of 54,866 is 12.7% higher than the 9945's 48,664, and its data compression score of 684,470 beats the 9945's 579,972 by 18%. The 9945, however, wins the single-thread test by a hair: 4,619 versus 4,597, a 0.5% margin. That result flips the usual expectation, suggesting the 65 W part can hold its single-core boost just as well, or slightly better, than the higher-power sibling.

For buyers who prioritize raw throughput in rendering, encryption, or scientific computing, the Ryzen 9 PRO 9955 is the data-backed pick. For buyers who need a 12-core workstation CPU with lower power draw and nearly identical single-thread performance, the Ryzen 9 PRO 9945 offers a compelling alternative that gives up meaningful multi-core ground but keeps the same core count, cache, and memory support. The database also places the 9955 at the 97th percentile among all CPUs, versus the 96th percentile for the 9945, so both are elite parts by any measure.

Where Each One Wins

The Ryzen 9 PRO 9955 dominates every multi-threaded benchmark in the head-to-head set. Its largest win comes in prime number finding, where it scores 461 versus 342 for the 9945, a 34.8% advantage. Extended instruction tests favor the 9955 by 23.7% (54,903 versus 44,374), data compression by 18% (684,470 versus 579,972), and random string sorting by 15.2% (71,928 versus 62,458). These are classic all-core workloads that scale with sustained power delivery, and the 120 W TDP of the 9955 gives it the headroom to maintain higher clocks across all 12 cores.

The 9945's only wins are the two single-thread entries, both showing 4,619 versus 4,597, a 0.5% edge. That margin is within noise for most real-world applications, but it does indicate that the 65 W part does not sacrifice any single-core boost capability. In fact, the 9945's single-thread score is slightly higher than the 9955's, which suggests the lower power envelope may allow the boost algorithm to hit its ceiling more consistently on lightly threaded tasks.

For floating-point math, the 9955 leads 121,509 versus 107,340 (13.2%), and for integer math it leads 182,312 versus 171,175 (6.5%). Physics simulation favors the 9955 by 14.8% (3,332 versus 2,902), and data encryption by 10.9% (33,754 versus 30,450). The pattern is consistent: the 9955 wins wherever the workload can use more than a couple of threads, while the 9945 holds its own only on single-threaded tasks.

Architecture Differences

Both processors are built on the same Granite Ridge die, part of AMD's 9000 series, with a 4 nm process from TSMC. They share the same transistor count of 16,630 million and the same die size of 2x 70.6 mm², indicating that the silicon itself is identical. The difference lies entirely in the power configuration: the Ryzen 9 PRO 9955 is rated at 120 W TDP, while the Ryzen 9 PRO 9945 is rated at 65 W TDP.

The core and cache layout is identical. Each core has 80 KB of L1 cache and 1 MB of L2 cache, with a shared 64 MB L3 cache across the chip. Both support DDR5 memory in dual-channel configuration with a memory bandwidth of 89.6 GB/s, and both support ECC memory. PCIe connectivity is also the same: Gen 5 with 24 lanes from the CPU. Both include integrated Radeon Graphics, and both are locked (multiplier unlocked: false), so overclocking is not an option on either part.

The release dates differ: the Ryzen 9 PRO 9945 launched on September 15, 2025, while the Ryzen 9 PRO 9955 launched on June 29, 2026. The part numbers also differ (100-000001407 for the 9945, 100-000001971 for the 9955), but there is no architectural revision between them. Both are listed as Active in production status and target the Server/Workstation market segment. The socket is AM5 for both, and both are built for the same platform.

The key takeaway from the architecture data is that the 9955 and 9945 are the same CPU at heart, differentiated only by TDP. The 9955's higher power budget allows it to sustain higher all-core clocks, which explains the consistent multi-thread wins. The 9945's lower TDP makes it a more power-efficient option for chassis with limited cooling or power delivery, while retaining the same single-thread performance ceiling.

FAQ

Q: Which CPU has better single-thread performance?

A: The Ryzen 9 PRO 9945 edges out the 9955 in the single-thread benchmark, scoring 4,619 versus 4,597, a 0.5% difference. This is the only test where the 9945 wins.

Q: How much faster is the Ryzen 9 PRO 9955 in multi-thread workloads?

A: The 9955 scores 54,866 in the multithread test versus 48,664 for the 9945, a 12.7% advantage. In data compression, the gap grows to 18% (684,470 versus 579,972).

Q: Are the two CPUs built on the same architecture?

A: Yes, both use the Granite Ridge codename from the Ryzen 9 (Zen 5) generation, manufactured on TSMC's 4 nm process with 16,630 million transistors and a 2x 70.6 mm² die size.

Q: What is the main difference between the two parts?

A: The Ryzen 9 PRO 9955 has a TDP of 120 W, while the Ryzen 9 PRO 9945 has a TDP of 65 W. All other specifications, including core count, clocks, cache, memory support, and PCIe lanes, are identical.

Q: Which CPU should I choose for a power-constrained build?

A: The Ryzen 9 PRO 9945 with its 65 W TDP offers nearly the same single-thread performance (4,619 versus 4,597) and only sacrifices multi-thread throughput, making it the better fit for lower-power systems.

Q: How do these CPUs compare to other processors in the database?

A: The 9955 ranks at the 97th percentile among all CPUs, with an average score of 110,612, placing it 1.8% ahead of the Intel Xeon w7-2595X and 3.9% ahead of the AMD Ryzen 9 9850HX. The 9945 ranks at the 96th percentile, with an average score of 96,083, placing it 0.3% ahead of the AMD EPYC 4565P.

Head-to-Head Benchmarks

The head-to-head data tells a consistent story of power scaling. The Ryzen 9 PRO 9955 wins 9 of 11 tests, and its margins grow with the intensity of the workload. The largest gap is in prime number finding, where the 9955 scores 461 versus 342 for the 9945, a 34.8% advantage. This test is highly sensitive to sustained all-core clock speeds, and the 120 W TDP of the 9955 clearly allows it to maintain higher frequencies under load.

Extended instructions show the second-largest gap: 54,903 versus 44,374, a 23.7% delta. This workload exercises AVX-style instruction paths and benefits from the same sustained clock advantage. Data compression follows at 18% (684,470 versus 579,972), and random string sorting at 15.2% (71,928 versus 62,458). Physics simulation shows a 14.8% gap (3,332 versus 2,902), and floating-point math a 13.2% gap (121,509 versus 107,340).

The multithread test, which is a broad measure of all-core throughput, shows a 12.7% gap (54,866 versus 48,664). Data encryption shows a 10.9% gap (33,754 versus 30,450), and integer math the smallest multi-thread gap at 6.5% (182,312 versus 171,175). Integer workloads are often less power-hungry than floating-point or vector workloads, which explains the relatively smaller margin.

The single-thread results flip the script. Both the passmark_single_thread and passmark_singlethread tests (which are duplicate entries in the database) show the 9945 winning with 4,619 versus 4,597, a 0.5% delta. This is a remarkably small difference, but it is consistent across both entries. It suggests that the 9945's lower TDP does not hamper its ability to boost a single core to maximum clock speed, and it may even allow slightly better boost behavior under light load.

Overall, the Ryzen 9 PRO 9955 is the clear performance leader in every multi-threaded metric, with gains ranging from 6.5% to 34.8%. The Ryzen 9 PRO 9945 is the single-thread champion by a tiny margin, and it offers the same core, cache, and memory configuration at half the TDP. For buyers who can accept the lower multi-thread throughput, the 9945 is a legitimate alternative; for those who need maximum compute density, the 9955 is the data-backed winner.