AMD Ryzen 5 PRO 8645HS vs Intel Core Ultra 9 285 Comparison

AMD Ryzen 5 PRO 8645HS and Intel Core Ultra 9 285 occupy opposite ends of the performance spectrum, and the benchmark data is unambiguous: the Intel part wins every single recorded test in the comparison. The Core Ultra 9 285 takes all 17 head-to-head benchmarks, with deltas ranging from a narrow 21% advantage in single-threaded work to a dominant 84.1% lead in prime number computation. The Ryzen 5 PRO 8645HS is a mobile processor built for efficiency and balanced daily workloads, while the Core Ultra 9 285 is a desktop flagship designed to maximize throughput across heavily threaded and compute-intensive tasks. The data does not show a single category where the AMD chip pulls ahead, making the use-case split a matter of platform and power envelope rather than raw performance supremacy.

Where Each One Wins

The Intel Core Ultra 9 285 wins everywhere in the recorded data, but the margin varies significantly by workload type. In Cinebench tests, the Intel part dominates multi-core rendering by a consistent 59.7% margin across R15, R20, and R23. Single-core Cinebench results show the same 59.7% gap, meaning the Intel processor's architectural advantage is not limited to thread count; it also delivers substantially higher per-thread performance. The Ryzen 5 PRO 8645HS cannot close the gap in any rendering scenario.

PassMark results reinforce the same pattern with different magnitudes. The smallest Intel win is in single-thread performance, where the Core Ultra 9 285 scores 4881 against the Ryzen's 3858, a 21% advantage. The largest gap appears in find prime numbers, where Intel leads 459 to 73, a 84.1% difference that indicates a massive advantage in integer-heavy, branch-heavy workloads. Floating point math also favors Intel heavily, with a 76.7% lead (194988 versus 45481). Data compression and integer math each show a 55.9% gap, while data encryption shows a 63% lead for Intel. Physics simulation shows a 66.4% Intel advantage, and random string sorting shows a 51.8% lead. The multithread PassMark score goes to Intel by 58.4%, and extended instructions go to Intel by 53.2%.

The Ryzen 5 PRO 8645HS does not record a single win, so its "winning" scenario is defined by what the data does not show: lower power draw, a smaller process node, and a mobile platform. The recorded TDP values indicate the AMD chip consumes 45 watts against the Intel's 65 watts, and the AMD processor uses a 4 nm node versus Intel's 3 nm node, though the Intel part is built by the same foundry. For a user constrained by a laptop chassis and battery budget, the Ryzen part is the only viable option of the two, but that is a platform decision, not a performance verdict.

Architecture Differences

The two processors come from fundamentally different design philosophies. The AMD Ryzen 5 PRO 8645HS uses Zen 4 architecture under the Hawk Point codename, part of the 8000 series. It is built on a 4 nm process at TSMC with 25,000 million transistors on a 178 mm² die. The Intel Core Ultra 9 285 uses Arrow Lake architecture, specifically Arrow Lake-S, part of Core Ultra Series 2. It is built on a 3 nm process, also at TSMC, with 17,800 million transistors on a larger 243 mm² die. Despite having fewer transistors, the Intel die is physically larger, which suggests a different transistor density and layout strategy.

Core configuration differs sharply. The Ryzen part has 6 cores and 12 threads, relying on simultaneous multithreading to reach 12 threads from 6 physical cores. The Intel part has 24 cores and 24 threads, with no multithreading, meaning every thread maps to a dedicated physical core. This explains why the Intel chip wins multi-core tests by such large margins: it has four times the physical cores, even if its per-core clock behavior differs.

Cache hierarchies also diverge. The AMD chip provides 64 KB of L1 per core, 1 MB of L2 per core, and 16 MB of shared L3. The Intel chip provides 192 KB of L1 per core, 3 MB of L2 per core, and 36 MB of shared L3. The Intel part has larger per-core caches and more than double the shared L3, which benefits workloads with large working sets. Neither part uses 3D V-Cache, and neither reports a total L3 figure beyond the shared amount.

Memory and I/O differ as well. Both support DDR5 and dual-channel memory, but the Intel part has a higher memory bandwidth rating of 102.4 GB/s versus 89.6 GB/s for AMD. Both support ECC memory. PCIe generation differs: AMD uses Gen 4 with 20 CPU lanes, while Intel uses Gen 5 with 20 CPU lanes. The integrated graphics also differ, with AMD using Radeon 760M and Intel using Arc Xe-LPG Graphics 64EU.

Head-to-Head Benchmarks

The Cinebench results tell a consistent story. In Cinebench R15 multi-core, the Intel part scores 4933 against 1989 for AMD, a 59.7% delta. R15 single-core shows 696 versus 280, also 59.7%. R20 multi-core gives 20556 against 8291, another 59.7% gap, and R20 single-core gives 2901 versus 1170. R23 multi-core shows 48945 against 19742, and R23 single-core shows 6909 against 2787. Every Cinebench test, single or multi-core, lands at the same 59.7% delta, which indicates the Intel architecture holds a uniform per-clock advantage over AMD in this rendering workload.

PassMark results show more variation. The single-thread test gives Intel a 21% lead (4881 versus 3858), the smallest margin in the entire comparison. This suggests that in lightly threaded, latency-sensitive tasks, the Core Ultra 9 285 is strong but not overwhelming. The data compression test shows a 55.9% Intel lead (602121 versus 265826), and integer math shows the same 55.9% gap (164869 versus 72740). Extended instructions show a 53.2% lead (45357 versus 21212). Random string sorting shows a 51.8% lead (73651 versus 35472). Data encryption shows a 63% lead (46949 versus 17387). Physics shows a 66.4% lead (3598 versus 1208). Floating point math shows a 76.7% lead (194988 versus 45481). The largest gap is find prime numbers, where Intel scores 459 against 73, an 84.1% delta. The multithread PassMark score shows a 58.4% Intel lead (56602 versus 23569).

Specification Differences

The two processors differ in nearly every major specification field. The AMD Ryzen 5 PRO 8645HS has 6 cores and 12 threads, while the Intel Core Ultra 9 285 has 24 cores and 24 threads. Base clocks differ substantially: AMD runs at 4.30 GHz, Intel at 2.50 GHz. Boost clocks flip the relationship: AMD boosts to 5.00 GHz, Intel boosts to 5.60 GHz. TDP differs by 20 watts, with AMD at 45 watts and Intel at 65 watts. Sockets are incompatible: AMD uses Socket FP7, Intel uses Socket 1851. Process nodes differ by one generation step, with AMD on 4 nm and Intel on 3 nm, both at TSMC. Transistor counts are 25,000 million for AMD and 17,800 million for Intel. Die size is 178 mm² for AMD and 243 mm² for Intel. Cache differs at every level: L1 is 64 KB per core for AMD versus 192 KB per core for Intel, L2 is 1 MB per core versus 3 MB per core, and L3 is 16 MB shared versus 36 MB shared. Memory bandwidth is 89.6 GB/s for AMD and 102.4 GB/s for Intel. PCIe is Gen 4 for AMD and Gen 5 for Intel, both with 20 CPU lanes. Integrated graphics are Radeon 760M for AMD and Arc Xe-LPG Graphics 64EU for Intel. Market segments differ: mobile for AMD, desktop for Intel. Release dates differ: April 2024 for AMD and December 2024 for Intel. The Intel part lists a launch MSRP of $579. Neither processor has an unlocked multiplier.

FAQ

Q: Which processor has more cores?

A: The Intel Core Ultra 9 285 has 24 cores and 24 threads, while the AMD Ryzen 5 PRO 8645HS has 6 cores and 12 threads.

Q: Which processor has the higher boost clock?

A: The Intel Core Ultra 9 285 boosts to 5.60 GHz, while the AMD Ryzen 5 PRO 8645HS boosts to 5.00 GHz. The AMD part has a higher base clock at 4.30 GHz versus 2.50 GHz.

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

A: In the PassMark single-thread test, the Intel part leads by 21%, scoring 4881 against 3858. In Cinebench R23 single-core, the Intel lead is 59.7%, with a score of 6909 versus 2787.

Q: Do both processors support ECC memory?

A: Yes, both the AMD Ryzen 5 PRO 8645HS and the Intel Core Ultra 9 285 support ECC memory, and both use DDR5 with dual-channel memory buses.

Q: Which processor has the larger L3 cache?

A: The Intel Core Ultra 9 285 has 36 MB of shared L3 cache, while the AMD Ryzen 5 PRO 8645HS has 16 MB of shared L3 cache.

Q: In which benchmark does the Intel processor show its largest advantage?

A: The largest Intel lead is in the PassMark find prime numbers test, where Intel scores 459 against 73, a 84.1% delta.

The Verdict

The data directs different buyers to different processors, though not because of any AMD benchmark victory. The Intel Core Ultra 9 285 is the clear performance choice in every recorded metric. It holds a 59.7% lead across all Cinebench tests, a 21% lead in PassMark single-thread, and leads by 84.1% in prime number computation. Its 24 physical cores, 36 MB of L3 cache, 5.60 GHz boost clock, and 102.4 GB/s memory bandwidth provide a decisive edge for rendering, encryption, physics simulation, and floating point workloads. The Intel part also sits at the 95th percentile among all CPUs, with an average benchmark score of 75488, and its nearest rivals are EPYC and Ryzen PRO parts with similar average scores, indicating it is firmly in high-end desktop territory.

The AMD Ryzen 5 PRO 8645HS is not a competitive alternative in raw throughput. Its 6 cores, 12 threads, 16 MB of L3, and 89.6 GB/s memory bandwidth place it far behind, and its average benchmark score of 30879 puts it at the 82nd percentile. Its nearest rivals include the Intel Core i7-13700TE and the AMD Ryzen 9 8945HS, all within a 0.6% band of its average score. The AMD part belongs in a mobile platform, where its 45 watt TDP and 4 nm process make sense for battery-powered systems. For anyone building a desktop workstation or high-performance machine, the Intel Core Ultra 9 285 is the only choice supported by the data. For anyone needing a laptop processor, the Ryzen 5 PRO 8645HS is the only one of the two that fits, and its performance is adequate for general productivity despite losing every comparison here.