Intel Core i9-12900K vs Intel Core Ultra 7 356H Comparison

Head-to-Head Benchmarks

The recorded data presents a clear split between these two Intel processors. The Intel Core i9-12900K wins 13 of the 17 head-to-head comparisons, while the Intel Core Ultra 7 356H takes 4. The magnitude of those wins tells the real story: the desktop chip dominates in heavily threaded workloads, while the mobile chip shows surprising strength in specific single-thread and physics-based tasks.

The largest victory for the i9-12900K comes in PassMark integer math, where it scores 139090 against the Ultra 7's 83111, a 67.4% advantage. Data compression follows closely, with the i9 reaching 537341 versus 336177, a 59.8% lead. Cinebench R23 multicore shows a 42% gap (26125 vs 18395), while random string sorting favors the i9 by 39.3% (57094 vs 40990). These are decisive margins that reflect the i9's higher core clock speeds and greater thread count.

The Ultra 7 356H fights back in PassMark find prime numbers, scoring 327 versus 147, a 55% advantage that is its biggest win. It also leads in PassMark physics by 23.4% (2895 vs 2219) and edges out the i9 in Cinebench R15 single-core by 4.6% (303 vs 289). The R23 single-core result is close as well, with the Ultra 7 ahead by 1.7% (2040 vs 2004.5). These wins indicate that the newer Panther Lake architecture has refined per-core efficiency, even if it cannot match the older chip's raw multi-threaded output.

In mixed workloads, the i9 holds narrower but consistent leads. PassMark floating point math is nearly even at 2.3% (105471 vs 103128), and PassMark single-thread shows just a 1.6% edge (4136 vs 4072). Data encryption favors the i9 by 12.3% (29579 vs 26345), and extended instructions by 20.7% (33682 vs 27898). The Cinebench R20 results are interesting: the i9 wins both multi-core (14679 vs 12153, up 20.8%) and single-core (2072 vs 1715, also up 20.8%). That single-core R20 margin is notable because it contradicts the R15 and R23 single-core results, suggesting the i9's higher boost clock of 5.20 GHz helps in certain short-duration tasks.

Overall average benchmark scores put the i9 at 42335 versus 41215 for the Ultra 7, a difference of roughly 2.7%. Both CPUs sit in the 87th to 88th percentile of all recorded processors, so the database places them in the same performance tier despite their very different designs.

Architecture Differences

The i9-12900K uses the Alder Lake architecture on a 10 nm process, while the Ultra 7 356H employs Panther Lake on a 3 nm node. This process shrink explains much of the Ultra 7's efficiency advantage, though the database does not record power efficiency directly. The i9 is a desktop part on Intel Socket 1700, while the Ultra 7 is a mobile part on Intel BGA 2540, so they are not physically interchangeable.

Both chips have 16 cores, but the i9 supports 24 threads through Hyper-Threading, whereas the Ultra 7 runs 16 threads with no multithreading. This thread disparity is the primary reason for the i9's multi-core dominance. The i9's base clock is 3.20 GHz with a 5.20 GHz boost, compared to 1.90 GHz base and 4.70 GHz boost for the Ultra 7. The i9 also carries a 125 W TDP versus 25 W for the mobile part, which reflects the desktop chip's higher sustained power delivery.

Cache layouts differ substantially. The i9 uses 80 KB L1 per core, 1.25 MB L2 per core, and 30 MB shared L3. The Ultra 7 uses 192 KB L1 per core, 2.5 MB L2 per core, and 18 MB shared L3. The Ultra 7's larger per-core L1 and L2 caches support its strong single-thread results, while the i9's larger shared L3 helps with multi-threaded data sharing.

Memory support also diverges. The i9 accepts DDR4 and DDR5 in dual-channel mode with 76.8 GB/s bandwidth and ECC support. The Ultra 7 supports DDR5 and LPDDR5X, also dual-channel, but with a higher 115.2 GB/s bandwidth and no ECC. PCIe connectivity favors the i9 with 16 Gen 5 lanes from the CPU, while the Ultra 7 provides 12 Gen 5 lanes. Integrated graphics differ as well: UHD Graphics 770 on the i9 versus Intel Xe3 Graphics on the Ultra 7.

The i9 was released on 2021-11-03 with a launch MSRP of $599, while the Ultra 7 launched on 2026-01-04 with no recorded MSRP. The i9 has an unlocked multiplier for overclocking; the Ultra 7 is locked. Production status for both is listed as Active.

The Verdict

The data directs different buyers to different chips. The Intel Core i9-12900K is the clear choice for anyone running heavily threaded workloads: video rendering, 3D animation, data compression, or software compilation. Its 42% lead in Cinebench R23 multi-core and 67.4% lead in integer math are not marginal differences; they represent substantial time savings in long-running tasks. The i9 also holds a 1.6% edge in PassMark single-thread, so it is not sacrificing basic responsiveness for that multi-core power.

The Intel Core Ultra 7 356H makes sense for mobile systems where the 25 W TDP is a practical necessity. Its 55% win in find prime numbers and 23.4% win in physics suggest that certain scientific or simulation workloads actually run better on the newer architecture. The Ultra 7's 1.7% lead in Cinebench R23 single-core shows that Panther Lake has caught up in per-thread performance, even if the overall average benchmark score is 2.7% lower.

For a desktop builder, the i9-12900K offers a higher average score (42335 vs 41215) and wins 13 of 17 direct comparisons. For a laptop buyer, the Ultra 7 356H provides competitive single-thread performance at a fraction of the power draw. The database does not record power consumption benchmarks, but the TDP figures of 125 W versus 25 W are the strongest available indicator of the efficiency gap.

FAQ

Q: Which processor has the higher boost clock?

A: The Intel Core i9-12900K boosts to 5.20 GHz, while the Intel Core Ultra 7 356H boosts to 4.70 GHz.

Q: Do both CPUs support DDR5 memory?

A: Yes, both support DDR5. The i9-12900K also supports DDR4, while the Ultra 7 356H also supports LPDDR5X.

Q: Which chip wins in Cinebench R23 multi-core?

A: The i9-12900K scores 26125 versus 18395 for the Ultra 7 356H, a 42% advantage for the desktop chip.

Q: Is the Ultra 7 356H better in any single-core test?

A: Yes. It wins Cinebench R15 single-core (303 vs 289, up 4.6%) and Cinebench R23 single-core (2040 vs 2004.5, up 1.7%). The i9 wins R20 single-core (2072 vs 1715, up 20.8%).

Q: What is the thread count difference?

A: The i9-12900K has 24 threads across 16 cores, while the Ultra 7 356H has 16 threads across 16 cores. The i9 supports Hyper-Threading; the Ultra 7 does not.

Q: Which CPU has more PCIe lanes from the processor?

A: The i9-12900K provides 16 Gen 5 lanes, while the Ultra 7 356H provides 12 Gen 5 lanes.

Where Each One Wins

The i9-12900K wins in every heavy multi-threaded category recorded. Data compression (59.8% lead), integer math (67.4% lead), random string sorting (39.3% lead), and Cinebench R23 multi-core (42% lead) are all tasks that scale with thread count and sustained clock speed. The i9 also wins in data encryption (12.3%) and extended instructions (20.7%), which benefit from its higher boost clock and larger shared L3 cache. For Cinebench R20, the i9 wins both multi-core and single-core by identical 20.8% margins, showing that its Alder Lake design handles that specific workload particularly well.

The Ultra 7 356H wins in PassMark find prime numbers (55% lead), which is a test that rewards per-core efficiency and larger L2 cache. Its 192 KB L1 and 2.5 MB L2 per core provide a structural advantage for this workload. The physics test (23.4% lead) similarly benefits from the newer 3 nm process and improved instruction handling. The Ultra 7 also edges out the i9 in Cinebench R15 and R23 single-core, though by smaller margins of 4.6% and 1.7%. These wins suggest the Ultra 7 is the better choice for lightly threaded, latency-sensitive applications, while the i9 dominates any workload that can use more than 16 threads.

Specification Differences

The two chips differ in nearly every core specification. The i9-12900K has 16 cores and 24 threads, versus 16 cores and 16 threads for the Ultra 7 356H. Base clocks are 3.20 GHz versus 1.90 GHz, and boost clocks are 5.20 GHz versus 4.70 GHz. TDP is 125 W versus 25 W. The i9 uses Intel Socket 1700; the Ultra 7 uses Intel BGA 2540.

Process node is 10 nm for Alder Lake versus 3 nm for Panther Lake. Cache sizes differ at every level: 80 KB versus 192 KB L1 per core, 1.25 MB versus 2.5 MB L2 per core, and 30 MB versus 18 MB shared L3. Memory bandwidth is 76.8 GB/s for the i9 versus 115.2 GB/s for the Ultra 7. ECC support is present on the i9 but absent on the Ultra 7. PCIe lanes from the CPU are 16 versus 12, both Gen 5. Integrated graphics are UHD Graphics 770 versus Intel Xe3 Graphics. The i9 has an unlocked multiplier; the Ultra 7 is locked. Release dates are 2021-11-03 versus 2026-01-04. The i9 has a launch MSRP of $599; the Ultra 7 has no recorded MSRP.