AMD EPYC 4565P vs AMD Ryzen 9 9955HX Comparison

Head-to-Head Benchmarks

The head-to-head data is decisively lopsided, with the AMD EPYC 4565P taking 14 of 15 benchmarks. The single exception is Cinebench R15 multi-core, where the Ryzen 9 9955HX scores 5905 against the EPYC's 5484, a 7.1% advantage. That is the only test the mobile chip wins, and it is worth remembering this is an older benchmark that often favors higher boost clocks over sustained throughput.

Every other comparison favors the EPYC, often by substantial margins. The largest gap appears in Cinebench R23 single-core, where the EPYC scores 7680 versus 2174 for the Ryzen — a 253.3% difference. That is not a typo; the EPYC more than triples the Ryzen's single-thread result in that test. The R23 multi-core gap is also enormous: 54405 versus 37159, a 46.4% advantage for the EPYC. Cinebench R15 single-core shows a 130.4% lead for the EPYC (774 vs 336), confirming that the single-thread deficit is not an artifact of one benchmark.

Moving to PassMark workloads, the EPYC leads in every category. Data compression shows an 860786 score against 731998, a 17.6% edge. Data encryption is 48268 versus 37330, a 29.3% advantage. Extended instructions come in at 64345 versus 57946, an 11% lead. Floating point math is 152003 against 136682, an 11.2% margin. Integer math shows 250683 versus 212598, a 17.9% advantage. The multithread score is 63474 versus 56171, a 13% gap. Physics tests show 2976 versus 2720, a 9.4% lead. Random string sorting is 81318 versus 77890, a 4.4% edge. Even the closest PassMark results — find prime numbers at 294 versus 287, a 2.4% margin — go to the EPYC.

Single-thread PassMark scores tell a similar story: 4712 versus 4393, a 7.3% advantage for the EPYC. The average benchmark score reinforces this: the EPYC sits at 95764 average versus 91199 for the Ryzen. Both CPUs land in the 96th percentile of all CPUs, but the EPYC's nearest rivals include the AMD EPYC 9175F (delta of 0.2%) and the AMD Ryzen 9 PRO 9945 (delta of -0.3%), while the Ryzen 9 9955HX's nearest rivals include the Intel Xeon 654 (delta of 0.5%) and the Intel Core Ultra 7 270K Plus (delta of -2.8%). The data shows the EPYC is competing in a higher performance tier, even if both are in the same percentile band.

The Verdict

The verdict is straightforward: choose the EPYC 4565P for anything that rewards raw compute throughput. It wins 14 of 15 head-to-head benchmarks, with particularly massive leads in single-threaded Cinebench tests (130.4% and 253.3%) and a 46.4% lead in R23 multi-core. It is also 13% ahead in PassMark multithread and 17.6% ahead in data compression, making it the stronger choice for compilers, rendering, and any workload that scales across cores.

The Ryzen 9 9955HX has one clear win — Cinebench R15 multi-core — but that singular result does not outweigh the consistent losses elsewhere. If you are constrained by a 55W TDP envelope, the Ryzen's efficiency profile matters, but the benchmark data shows it simply cannot keep pace on raw performance. The EPYC's 170W TDP buys substantially more compute, and the data reflects that trade-off.

For a server or workstation that runs sustained workloads, the EPYC's higher base clock of 4.30 GHz versus 2.50 GHz on the Ryzen is a critical advantage. The Ryzen's boost clock of 5.40 GHz is lower than the EPYC's 5.70 GHz, and the benchmarks show that the EPYC maintains its lead even in short bursts. The Ryzen 9 9955HX is a mobile part, and the data says it belongs in a laptop where power limits are a hard constraint. The EPYC belongs in a socket where you can feed it.

Architecture Differences

Both CPUs are built on Zen 5 architecture, but they are different implementations. The EPYC 4565P uses the "Grado" codename from the EPYC 4005 series, while the Ryzen 9 9955HX uses the "Fire Range" codename from the 9000 series. Both are fabricated on a 4 nm process at TSMC, with the same transistor count of 16,630 million and the same die size of 2x 70.6 mm². The cache hierarchy is identical: 80 KB of L1 per core, 1 MB of L2 per core, and 64 MB of shared L3.

The integrated graphics differ. The EPYC includes Radeon Graphics, while the Ryzen includes Radeon 610M. The EPYC is a server/workstation part with a production status of Active and a release date of 2025-05-12. The Ryzen is a mobile part with a release date of 2025-01-05. The EPYC has a locked multiplier, while the Ryzen's multiplier is unlocked. The socket is a major divergence: the EPYC uses AMD Socket AM5, and the Ryzen uses AMD Socket FL1.

Memory support is identical on paper — both use DDR5 with dual-channel memory buses and 89.6 GB/s bandwidth, and both support ECC memory. The PCIe lanes differ slightly: the EPYC provides Gen 5 with 24 lanes (CPU only), while the Ryzen provides Gen 5 with 28 lanes (CPU only). The EPYC's part number is 100-000001559, and the Ryzen's is 100-000001028. The EPYC has a launch MSRP of $589; the Ryzen has no listed launch MSRP.

Specification Differences

The core and thread counts are identical — 16 cores and 32 threads on both. The base clocks differ significantly: the EPYC runs at 4.30 GHz, and the Ryzen at 2.50 GHz. Boost clocks are closer but still favor the EPYC: 5.70 GHz versus 5.40 GHz. The TDP is a major differentiator: 170W for the EPYC versus 55W for the Ryzen. The sockets are different, as noted. The market segment separates them clearly — server/workstation for the EPYC, mobile for the Ryzen. The multiplier is locked on the EPYC and unlocked on the Ryzen. The integrated GPU models differ. The PCIe lane counts differ by four lanes.

FAQ

Q: Which CPU wins more head-to-head benchmarks?

A: The AMD EPYC 4565P wins 14 of 15 benchmarks. The only win for the AMD Ryzen 9 9955HX is Cinebench R15 multi-core, where it scores 5905 versus 5484.

Q: How large is the single-threaded performance gap?

A: The EPYC leads by 130.4% in Cinebench R15 single-core (774 vs 336) and by 253.3% in Cinebench R23 single-core (7680 vs 2174). In PassMark single-thread, the EPYC leads by 7.3% (4712 vs 4393).

Q: Is there any workload where the Ryzen 9 9955HX is faster?

A: Yes, in Cinebench R15 multi-core, the Ryzen scores 5905 against the EPYC's 5484, a 7.1% advantage. That is the only benchmark in the head-to-head data where the Ryzen wins.

Q: What is the TDP difference between the two?

A: The EPYC 4565P has a TDP of 170W, and the Ryzen 9 9955HX has a TDP of 55W. This is a 115W difference, reflecting the EPYC's server-oriented power envelope versus the Ryzen's mobile efficiency focus.

Q: Do both CPUs support the same memory and ECC?

A: Yes, both support DDR5, use dual-channel memory buses, have 89.6 GB/s bandwidth, and support ECC memory. The cache configuration is also identical: 80 KB L1 per core, 1 MB L2 per core, and 64 MB shared L3.

Q: How do their average benchmark scores compare?

A: The EPYC has an average benchmark score of 95764, while the Ryzen has 91199. Both are in the 96th percentile of all CPUs. The EPYC's nearest rival is the AMD EPYC 9175F with a 0.2% delta, while the Ryzen's nearest rival is the Intel Xeon 654 with a 0.5% delta.

Where Each One Wins

The EPYC 4565P wins in every category except one. It dominates in single-threaded workloads by a massive margin, with leads of 130.4% and 253.3% in the Cinebench R15 and R23 single-core tests. That makes it the clear choice for lightly threaded applications that still need high clock speeds — think database queries, scripting, or any interactive server workload. Its multi-threaded performance is also superior, with a 46.4% lead in R23 multi-core and a 13% lead in PassMark multithread. Encryption workloads show a 29.3% advantage, compression shows 17.6%, and integer math shows 17.9%. For any compute-heavy server task — rendering, compiling, data processing — the EPYC is the data-backed winner.

The Ryzen 9 9955HX wins exactly one benchmark: Cinebench R15 multi-core. That test is an older workload, and its 7.1% margin over the EPYC is the only bright spot. If your workload is specifically tuned to that benchmark's characteristics, the Ryzen has a claim. But the broader data shows it losing by double digits in most multi-threaded PassMark tests (13% in multithread, 17.6% in compression, 29.3% in encryption). The Ryzen's unlocked multiplier is a feature the EPYC lacks, which matters for overclockers, but the stock benchmark results do not favor it.

For a mobile platform where 55W is the power ceiling, the Ryzen 9 9955HX is the only sensible choice — the EPYC's 170W TDP is not mobile-feasible. But if you are building a desktop or server system and can supply the power, the EPYC's benchmark dominance is unambiguous. It wins 14 of 15 tests, often by huge margins, and its nearest rivals include other EPYC and Ryzen PRO parts, not mobile chips. The data says: buy the EPYC for compute, buy the Ryzen for a laptop.