Intel Core i9-9900K vs Intel Core Ultra 5 125H Comparison

The Verdict

The data shows a clear split based on workload. The Intel Core Ultra 5 125H wins 12 of 17 head-to-head benchmarks, while the Intel Core i9-9900K takes 5. The Ultra 5 125H is the better all-rounder in the database, with an average benchmark score of 27507 versus 27097 for the i9-9900K. Both sit at the 79th percentile against all CPUs, so they are broadly comparable in overall standing.

Pick the Core Ultra 5 125H if you need a mobile processor that dominates in encryption, prime number finding, floating-point math, and multi-threaded workloads. It is also the only option with an active production status and a 28W TDP, which points to efficiency-focused designs. Pick the Core i9-9900K if your priority is raw single-core speed in newer Cinebench versions, data compression, extended instruction throughput, or random string sorting, where it holds decisive leads. The i9-9900K is end-of-life and carries a 95W TDP, so it suits desktop builds where power draw is less of a concern.

For most users, the Core Ultra 5 125H is the safer recommendation. It matches the i9-9900K in overall percentile, wins more benchmarks, and does so in a mobile form factor. The i9-9900K is a niche pick for specific desktop tasks where its strengths align with the workload.

Architecture Differences

The two processors come from different eras and design philosophies. The Core Ultra 5 125H uses the Meteor Lake architecture on a 7 nm process, while the Core i9-9900K uses Coffee Lake-R on a 14 nm process. Both are Intel parts, but the node advantage for the Ultra 5 125H is substantial.

Core counts differ significantly. The Ultra 5 125H has 14 cores and 18 threads, while the i9-9900K has 8 cores and 16 threads. The Ultra 5 125H also has a larger L3 cache at 18 MB shared, versus 16 MB shared for the i9-9900K. Per-core cache layouts differ: the Ultra 5 125H has 112 KB L1 and 2 MB L2 per core, while the i9-9900K has 64 KB L1 and 256 KB L2 per core.

Clock speeds tell a different story. Both have a 3.60 GHz base clock, but the i9-9900K boosts to 5.00 GHz compared to 4.50 GHz for the Ultra 5 125H. That higher boost clock is a key factor in the i9-9900K's single-core wins. The i9-9900K also has an unlocked multiplier, while the Ultra 5 125H is locked.

Memory support diverges. The Ultra 5 125H uses DDR5 with memory bandwidth of 89.6 GB/s, while the i9-9900K uses DDR4 with 42.7 GB/s. Both are dual-channel. The Ultra 5 125H supports PCIe Gen 5, whereas the i9-9900K is limited to Gen 3 with 16 lanes on the CPU. Integrated graphics differ too: the Ultra 5 125H has Arc Xe-LPG 96EU, while the i9-9900K has UHD Graphics 630.

The socket and market segment are opposites. The Ultra 5 125H is a mobile part on Intel BGA 2049, released in December 2023. The i9-9900K is a desktop part on Intel Socket 1151, released in October 2018. The i9-9900K has a die size of 180.3 mm², while the Ultra 5 125H does not list one. Neither supports ECC memory.

Where Each One Wins

The Core Ultra 5 125H dominates in computational throughput across multiple benchmark families. In Cinebench R15 multicore, it scores 2021.5 versus 1545 for the i9-9900K, a 30.8% lead. Cinebench R20 shows similar patterns: 7161 versus 6439 multicore (11.2% ahead) and 1010 versus 908 single-core (11.2% ahead). The Ultra 5 125H also wins PassMark multithread with 21100 versus 18153 (16.2% ahead) and single-thread with 3399 versus 2919 (16.4% ahead).

Encryption is a standout. The Ultra 5 125H scores 14251 in PassMark data encryption versus 6430 for the i9-9900K, a 121.6% advantage. Prime number finding also favors the Ultra 5 125H: 88 versus 47, an 87.2% lead. Floating-point math goes to the Ultra 5 125H at 51670 versus 41036 (25.9% ahead), and physics simulation shows a 54.1% lead (1439 versus 934). Integer math is closer but still favors the Ultra 5 125H: 69986 versus 66134 (5.8% ahead).

The Core i9-9900K wins in Cinebench R23 and specific PassMark subtests. Cinebench R23 multicore goes to the i9-9900K at 15333 versus 12804.5, a 16.5% lead. Single-core R23 shows an even bigger gap: 2164 versus 1647.5, a 23.9% lead. Data compression favors the i9-9900K at 283506 versus 236209 (16.7% ahead). Extended instructions score 18965 versus 13749 (27.5% ahead), and random string sorting is 36238 versus 27435 (24.3% ahead).

The pattern is clear: the Ultra 5 125H wins in modern multi-core and math-heavy workloads, while the i9-9900K wins in older Cinebench versions, compression, and extended instruction sets.

FAQ

Q: Which processor has more cores and threads?

A: The Intel Core Ultra 5 125H has 14 cores and 18 threads. The Intel Core i9-9900K has 8 cores and 16 threads.

Q: How do they compare in overall benchmark scores?

A: The Ultra 5 125H has an average benchmark score of 27507, which is 0.1% below the AMD Ryzen 7 5800 and 0.3% below the Intel Core i5-12600K. The i9-9900K scores 27097, which is 0.2% above the AMD Ryzen 7 5700G and 0.6% above the AMD Ryzen AI 7 445. Both sit at the 79th percentile against all CPUs.

Q: Which processor is better for encryption workloads?

A: The Ultra 5 125H is dramatically better. It scores 14251 in PassMark data encryption versus 6430 for the i9-9900K, a 121.6% advantage.

Q: Does the i9-9900K win any benchmarks?

A: Yes, it wins 5 of 17 head-to-head tests. These include Cinebench R23 multicore (15333 versus 12804.5), Cinebench R23 single-core (2164 versus 1647.5), PassMark data compression (283506 versus 236209), extended instructions (18965 versus 13749), and random string sorting (36238 versus 27435).

Q: What are the TDP differences?

A: The Ultra 5 125H has a 28W TDP, while the i9-9900K has a 95W TDP. This reflects the mobile versus desktop positioning.

Q: Which processor supports faster memory?

A: The Ultra 5 125H supports DDR5 with 89.6 GB/s bandwidth. The i9-9900K supports DDR4 with 42.7 GB/s bandwidth. Both use dual-channel memory buses.

Head-to-Head Benchmarks

The largest single win in the comparison belongs to the Ultra 5 125H in PassMark data encryption, where it scores 14251 against 6430 for the i9-9900K. That is a 121.6% delta, more than doubling the rival's output. The next biggest win is in PassMark find prime numbers: 88 versus 47, an 87.2% lead. These are not marginal differences; they represent fundamentally different execution capabilities.

The i9-9900K's biggest win is in Cinebench R23 single-core, where it scores 2164 versus 1647.5, a 23.9% lead. That is followed by extended instructions at 18965 versus 13749 (27.5% lead), though note the i9-9900K wins that test by a larger percentage than its R23 single-core win. Random string sorting goes to the i9-9900K by 24.3% (36238 versus 27435), and data compression by 16.7% (283506 versus 236209). Cinebench R23 multicore is the i9-9900K's only other win, at 15333 versus 12804.5 (16.5% lead).

Looking at the Cinebench family as a whole, the results are inconsistent. The Ultra 5 125H wins R15 multicore by 30.8%, R15 single-core by 11.1%, R20 multicore by 11.2%, and R20 single-core by 11.2%. But the i9-9900K wins R23 multicore by 16.5% and R23 single-core by 23.9%. This suggests the i9-9900K's higher 5.00 GHz boost clock matters more in the R23 workload, while the Ultra 5 125H's additional cores and threads carry it in R15 and R20.

PassMark results further split the field. The Ultra 5 125H wins multithread (21100 versus 18153, 16.2% ahead), single-thread (3399 versus 2919, 16.4% ahead), floating-point math (51670 versus 41036, 25.9% ahead), physics (1439 versus 934, 54.1% ahead), integer math (69986 versus 66134, 5.8% ahead), plus the encryption and prime number tests. The i9-9900K wins compression, extended instructions, and random string sorting. That is 7 PassMark wins for the Ultra 5 125H and 3 for the i9-9900K, with the remaining tests split across other benchmark families.

The overall win count stands at 12 for the Ultra 5 125H and 5 for the i9-9900K. The average benchmark scores reinforce this: 27507 for the Ultra 5 125H versus 27097 for the i9-9900K. The i9-9900K's nearest rival in the database is the AMD Ryzen 7 5700G at 27051, a 0.2% gap. The Ultra 5 125H's nearest rival is the AMD Ryzen 7 5800 at 27535, a 0.1% gap. Both processors are competitive within their respective peer groups, but the Ultra 5 125H edges ahead in aggregate performance.