Intel Core i9-13900KF vs Intel Core Ultra 7 255HX Comparison

The Intel Core Ultra 7 255HX and Intel Core i9-13900KF represent two distinct approaches to high-performance computing: one is a modern, power-efficient mobile processor built on a leading-edge node, while the other is a high-core-count desktop flagship from a previous generation. The benchmark data reveals a clear performance hierarchy, but the reasons behind the results are rooted in fundamental architectural differences that go far beyond simple core counts.

Head-to-Head Benchmarks

The head-to-head comparison is decisively lopsided, with the Intel Core i9-13900KF winning 15 of the 17 benchmark tests. The most dramatic victories for the desktop part come in single-threaded workloads. In Cinebench R23 single-core, the i9-13900KF scores 6897 points against the Ultra 7's 2163, a staggering 68.6% advantage. Similarly, in Cinebench R15 single-core, the i9-13900KF leads with 695 points versus 327, a 52.9% gap. These results indicate that the older architecture, despite its larger process node, delivers significantly higher per-core performance, likely due to higher boost clocks and a more mature design tuned for raw frequency.

Multi-threaded performance also favors the i9-13900KF, though the margins are smaller. In Cinebench R23 multi-core, the i9-13900KF scores 48855 versus 32612 for the Ultra 7, a 33.2% lead. The gap narrows in Cinebench R20 multi-core, where the i9-13900KF wins with 20519 points against 17187 (16.2% ahead). Interestingly, in Cinebench R15 multi-core, the two are nearly identical, with the i9-13900KF scoring 4924 and the Ultra 7 scoring 4916, a negligible 0.2% difference. This suggests that the Ultra 7's 20 cores and 20 threads can hold their own in certain lightly-threaded multi-core scenarios, but the i9-13900KF's additional 4 cores and 12 threads (24/32 versus 20/20) become decisive in heavier sustained workloads.

The PassMark suite paints a similar picture. The i9-13900KF dominates integer math (206859 vs 127126, 38.5% ahead), data compression (786218 vs 515143, 34.5% ahead), and random string sorting (86510 vs 62591, 27.6% ahead). It also wins in multithread (57729 vs 48234, 16.4% ahead), data encryption (46186 vs 39499, 14.5% ahead), extended instructions (46084 vs 41247, 10.5% ahead), and physics (2956 vs 2926, 1% ahead). Single-thread scores are virtually tied, with the i9-13900KF at 4584 and the Ultra 7 at 4562, a 0.5% margin that is within noise.

The Ultra 7 255HX does manage two wins, and they are noteworthy. In PassMark find prime numbers, it scores 400 against the i9-13900KF's 225, a commanding 77.8% lead. This test is highly sensitive to cache architecture and branch prediction, suggesting the Arrow Lake design has a particular strength in this specific workload. The second win is in floating-point math, where the Ultra 7 scores 160624 versus 150869, a 6.5% advantage. This indicates that the newer architecture's FPU pipeline is more efficient, even at lower clock speeds.

Architecture Differences

The performance gap is explained by the radically different designs. The Intel Core Ultra 7 255HX is built on a 3nm process at TSMC, while the Intel Core i9-13900KF uses Intel's 10nm node. This node advantage allows the Ultra 7 to pack 17,800 million transistors into a 243 mm² die, whereas the i9-13900KF's die is 257 mm² with a different transistor count. The Ultra 7 features 20 cores and 20 threads, all presumably using a unified architecture, while the i9-13900KF has 24 cores and 32 threads, implying a hybrid configuration with performance and efficiency cores (given the thread count disparity).

Cache hierarchies differ substantially. The Ultra 7 has a larger L1 cache at 192 KB per core and L2 at 3 MB per core, compared to 80 KB and 2 MB per core for the i9-13900KF. However, the i9-13900KF has a larger shared L3 cache at 36 MB versus 30 MB on the Ultra 7. The smaller per-core caches on the desktop part are compensated by the higher thread count and clock speeds. The i9-13900KF also has a higher base clock (3.00 GHz vs 2.40 GHz) and boost clock (5.80 GHz vs 5.20 GHz), directly contributing to its single-thread dominance.

The platform targets are completely different. The Ultra 7 is a mobile part on the Intel BGA 2114 socket, with a 55W TDP, while the i9-13900KF is a desktop part on the Intel Socket 1700 with a 125W TDP. The Ultra 7 supports only DDR5 memory with a dual-channel bus and 102.4 GB/s bandwidth, while the i9-13900KF supports both DDR4 and DDR5. The Ultra 7 includes integrated graphics (Arc Xe-LPG Graphics 64EU), while the i9-13900KF has none, requiring a discrete GPU. The Ultra 7 lacks ECC memory support, while the i9-13900KF supports it.

FAQ

Q: Which processor has a higher single-core score in Cinebench R23?

A: The Intel Core i9-13900KF is dramatically ahead, scoring 6897 points compared to the Core Ultra 7 255HX's 2163 points, a 68.6% lead.

Q: Are there any workloads where the Core Ultra 7 255HX wins?

A: Yes, the Ultra 7 wins two tests: PassMark find prime numbers (400 vs 225, a 77.8% lead) and PassMark floating-point math (160624 vs 150869, a 6.5% lead).

Q: What is the core and thread difference between the two?

A: The Core Ultra 7 255HX has 20 cores and 20 threads, while the Core i9-13900KF has 24 cores and 32 threads.

Q: How does the memory support differ?

A: The Core Ultra 7 255HX supports only DDR5 memory with a dual-channel bus and 102.4 GB/s bandwidth. The Core i9-13900KF supports both DDR4 and DDR5 memory.

Q: Do both processors have integrated graphics?

A: No. The Core Ultra 7 255HX includes Arc Xe-LPG Graphics 64EU, while the Core i9-13900KF has no integrated graphics.

Q: Which processor has a larger L3 cache?

A: The Intel Core i9-13900KF has a 36 MB shared L3 cache, while the Core Ultra 7 255HX has a 30 MB shared L3 cache.

The Verdict

The data is unambiguous: the Intel Core i9-13900KF is the superior processor in nearly every benchmark. It wins 15 of the 17 head-to-head tests, with particularly decisive margins in single-threaded Cinebench tests (52.9% to 68.6% ahead) and multi-threaded Cinebench R23 (33.2% ahead). Its 24 cores and 32 threads, combined with higher boost clocks, make it a more powerful part for both productivity and mainstream computing tasks. The Core Ultra 7 255HX's wins in find prime numbers and floating-point math are notable but isolated, indicating a specialized strength rather than general-purpose superiority.

However, the verdict is not simply "buy the i9." The Core Ultra 7 255HX is a mobile processor with a 55W TDP, designed for laptops, while the i9-13900KF is a desktop processor with a 125W TDP. The Ultra 7's integrated graphics and lower power draw make it viable for portable systems, but its performance is significantly lower. The i9-13900KF, with a launch MSRP of $564, targets desktop users who prioritize raw performance above all else. For a desktop user seeking maximum compute capability, the i9-13900KF is the clear choice. For a mobile user, the Ultra 7 offers a balance of performance and efficiency, but it will not match the desktop part's output.

Specification Differences

The two processors differ on several key specifications. The Core Ultra 7 255HX has 20 cores and 20 threads, while the Core i9-13900KF has 24 cores and 32 threads. The base clock is 2.40 GHz for the Ultra 7 versus 3.00 GHz for the i9-13900KF, and the boost clock is 5.20 GHz versus 5.80 GHz. The TDP is 55W versus 125W. The Ultra 7 is on the Intel BGA 2114 socket, while the i9-13900KF uses the Intel Socket 1700. The process node is 3nm (TSMC) for the Ultra 7 versus 10nm (Intel) for the i9-13900KF. The L1 cache is 192 KB per core for the Ultra 7 versus 80 KB per core, and L2 is 3 MB per core versus 2 MB per core. The L3 cache is 30 MB shared versus 36 MB shared. Memory support is DDR5 only for the Ultra 7 versus DDR4 and DDR5 for the i9-13900KF. The Ultra 7 has a memory bandwidth of 102.4 GB/s (the i9-13900KF's is not listed). ECC memory is false for the Ultra 7 and true for the i9-13900KF. The Ultra 7 includes integrated Arc Xe-LPG Graphics 64EU, while the i9-13900KF has none. The Ultra 7 has a part number SRVFG, and the i9-13900KF has SRMBJ.

Where Each One Wins

The Intel Core i9-13900KF is the winner for nearly all desktop-centric workloads. It excels in single-threaded tasks like web browsing, office applications, and legacy software that rely on high clock speeds, as shown by its massive Cinebench R23 single-core lead (6897 vs 2163). It is also the stronger multi-threaded part, winning Cinebench R23 multi-core by 33.2% and PassMark multithread by 16.4%, making it suited for video editing, 3D rendering, and compilation. Its wins in integer math (38.5% ahead) and data compression (34.5% ahead) reinforce its suitability for database and file-handling tasks. The i9-13900KF also wins in data encryption, extended instructions, and random string sorting, indicating broad dominance.

The Intel Core Ultra 7 255HX is the winner in two specific scenarios. First, it wins PassMark find prime numbers by 77.8%, a test that often stresses cache hierarchy and branch prediction; this could translate to advantages in certain scientific computing or cryptographic workloads. Second, it wins PassMark floating-point math by 6.5%, suggesting a more efficient FPU for tasks like scientific simulations or signal processing. Beyond these, the Ultra 7's integrated graphics provide a functional advantage for mobile systems where a discrete GPU is not present, and its lower TDP (55W vs 125W) makes it the only viable choice for battery-powered laptops. The near-tie in Cinebench R15 multi-core (4916 vs 4924) shows that the Ultra 7 can be competitive in lighter multi-threaded bursts, but it cannot sustain that performance against the i9's extra cores and threads.