Intel Core i9-9900KS vs Intel Xeon E-2356G Comparison

Head-to-Head Benchmarks

The benchmark data shows a clear overall winner, but not without a notable exception. Across the eight shared tests, the Intel Core i9-9900KS takes seven wins, with the Intel Xeon E-2356G securing a single, significant victory. The most dramatic difference is in Geekbench multicore, where the i9-9900KS scores 9,771 against the Xeon's 7,213, a 35.5% advantage. This is a substantial margin, reflecting the i9's higher thread count and core count in a test that scales heavily with parallel processing.

In the Cinebench suite, the i9-9900KS consistently leads by a narrow but uniform margin. In Cinebench R23 multicore, it scores 16,446 versus 15,632, a 5.2% difference, which mirrors the same delta seen in R20 multicore (6,907 vs 6,565) and R15 multicore (1,657 vs 1,575). The single-core Cinebench results follow the same pattern: R23 single-core shows 2,321 vs 2,206 (5.2% ahead), R20 single-core shows 974 vs 926 (5.2% ahead), and R15 single-core shows 233 vs 222 (5% ahead). These are consistent, small wins that indicate the i9-9900KS has a slight edge in lightly threaded workstation tasks, even though both CPUs boost to 5.00 GHz.

The Xeon's lone victory comes in Geekbench single-core, where it scores 2,044 against the i9's 1,715, a 16.1% advantage. This is a striking reversal. The Xeon's newer architecture, Rocket Lake, delivers a significant IPC improvement in this specific test, despite having a lower base clock of 3.20 GHz compared to 4.00 GHz. This result suggests that for applications that are purely single-threaded and sensitive to architectural efficiency, the Xeon is the better choice, even if it lags in multi-threaded scenarios.

Overall, the average benchmark scores reflect this split. The i9-9900KS has an average score of 4,738, placing it at the 59th percentile of all CPUs, while the Xeon E-2356G averages 4,548, at the 58th percentile. The i9 sits just 0.1% above the Intel Core i7-6950X (4,734) and 0.6% above the Intel Core i9-10900E (4,708), while the Xeon is essentially tied with the Intel Core i7-10700KF (4,547) and 0.1% ahead of the Intel Core i5-1340P (4,545).

Architecture Differences

The two processors represent different Intel design philosophies and eras. The i9-9900KS is built on Coffee Lake, specifically the Coffee Lake-R refresh, using a 14 nm process node from Intel. Its die size is 180 mm². The Xeon E-2356G is a Rocket Lake part, belonging to the Rocket Lake-E generation, also on a 14 nm node but with a significantly larger die at 276 mm². Both are manufactured by Intel, but the newer architecture of the Xeon delivers different core-level characteristics.

The core configurations diverge sharply. The i9-9900KS has 8 cores and 16 threads, while the Xeon has 6 cores and 12 threads. The i9's cache layout is 64 KB of L1 and 256 KB of L2 per core, with 16 MB of shared L3. The Xeon offers 80 KB of L1 and 512 KB of L2 per core, but only 12 MB of shared L3. This means the Xeon has more cache per core, but less total L3, which is relevant for workloads that exceed the smaller shared pool. The Xeon's larger per-core L2 is a likely contributor to its Geekbench single-core win.

Memory support is another differentiator. Both support DDR4 and dual-channel memory, but the Xeon's memory bandwidth is rated at 51.2 GB/s, higher than the i9's 42.7 GB/s. The Xeon also supports ECC memory, a critical feature for server and workstation stability, which the i9 lacks. The Xeon further advances in PCIe support, offering Gen 4 with 20 lanes from the CPU, while the i9 is limited to Gen 3 with 16 lanes. Integrated graphics also differ: the i9 uses UHD 630, while the Xeon ships with UHD Graphics P750. The Xeon has a locked multiplier, while the i9-9900KS is multiplier unlocked, a feature aimed at enthusiasts. The market segments reflect this split: the i9 is a desktop part, while the Xeon is designated for server and workstation use.

FAQ

Q: Which CPU has more cores and threads?

A: The Intel Core i9-9900KS has 8 cores and 16 threads. The Intel Xeon E-2356G has 6 cores and 12 threads.

Q: What is the biggest performance gap between the two in the recorded benchmarks?

A: The largest delta is in Geekbench multicore, where the i9-9900KS scores 9,771 compared to the Xeon's 7,213, which is a 35.5% advantage for the i9.

Q: Does the Xeon E-2356G win any benchmark?

A: Yes, it wins Geekbench single-core. It scores 2,044 against the i9's 1,715, a 16.1% advantage.

Q: Which processor supports ECC memory?

A: The Intel Xeon E-2356G supports ECC memory. The Intel Core i9-9900KS does not.

Q: How do the boost clocks compare?

A: Both CPUs have a boost clock of 5.00 GHz. The base clocks differ, with the i9 at 4.00 GHz and the Xeon at 3.20 GHz.

Q: What is the difference in PCIe support?

A: The Xeon E-2356G provides PCIe Gen 4 with 20 lanes from the CPU. The i9-9900KS provides PCIe Gen 3 with 16 lanes from the CPU.

Specification Differences

The two processors differ across nearly every major specification category. The i9-9900KS uses the Intel Socket 1151, while the Xeon E-2356G uses the Intel Socket 1200. The i9 is based on Coffee Lake architecture with a 180 mm² die, while the Xeon is based on Rocket Lake with a 276 mm² die. The core counts are 8 vs 6, and thread counts are 16 vs 12. Base clocks are 4.00 GHz for the i9 and 3.20 GHz for the Xeon, though both boost to 5.00 GHz. The i9 has a TDP of 127 W, while the Xeon is rated at 80 W.

Cache hierarchies are different: the i9 has 64 KB L1 and 256 KB L2 per core with 16 MB shared L3, while the Xeon has 80 KB L1 and 512 KB L2 per core with 12 MB shared L3. Memory bandwidth is higher on the Xeon at 51.2 GB/s versus 42.7 GB/s for the i9. ECC memory support is present only on the Xeon. PCIe generation and lane counts differ, with the Xeon offering Gen 4 with 20 lanes and the i9 offering Gen 3 with 16 lanes. Integrated graphics are UHD 630 on the i9 and UHD Graphics P750 on the Xeon. The i9 has an unlocked multiplier; the Xeon does not. The i9 is end-of-life, while the Xeon is active in production. The release dates are 2019-10-27 for the i9 and 2021-09-07 for the Xeon. The part numbers are SRG1Q for the i9 and SRKN2 for the Xeon.

Where Each One Wins

The Intel Core i9-9900KS is the clear winner for multi-threaded workloads. Its 35.5% lead in Geekbench multicore and consistent 5.2% advantage across all Cinebench multicore tests make it the superior choice for rendering, video encoding, and other tasks that use all available cores. The data shows it also wins every single-core Cinebench test, so it is not just about thread count; it holds a slight edge in those tasks as well. For a desktop user who prioritizes raw throughput in CPU-heavy applications, the i9's 8-core, 16-thread configuration delivers more performance.

The Intel Xeon E-2356G wins in one specific area: Geekbench single-core. Its 16.1% advantage there indicates that the Rocket Lake architecture has a meaningful IPC improvement that shines in workloads that are heavily dependent on a single thread. This could include certain legacy applications, some scripting workloads, or tasks that are not well parallelized. Additionally, the Xeon offers features that matter outside of raw benchmark scores: ECC memory support, higher memory bandwidth, PCIe Gen 4, and a lower TDP of 80 W. For a server or workstation environment where stability and data integrity are paramount, these features outweigh the multi-core performance deficit.

The Verdict

Based strictly on the benchmark data, the Intel Core i9-9900KS is the faster processor for most compute tasks. It wins 7 out of 8 head-to-head tests, including all multi-core and all Cinebench single-core tests. The 5.2% lead in Cinebench R23 multi-core (16,446 vs 15,632) and the dominant 35.5% lead in Geekbench multicore (9,771 vs 7,213) make it the pick for users who need maximum thread throughput. The i9 also has a higher average benchmark score of 4,738 versus 4,548 for the Xeon, and it sits at a 59th percentile versus the Xeon's 58th.

However, the Xeon E-2356G is not without reason for selection. Its 16.1% win in Geekbench single-core shows that it is the better choice for purely single-threaded performance, a rare but real scenario. More importantly, the Xeon's platform features, specifically ECC memory support, PCIe Gen 4, and higher memory bandwidth, make it the appropriate choice for a workstation or server where data integrity and modern I/O are required. The lower TDP of 80 W also makes it easier to cool in dense systems. The i9's launch MSRP was $513, while the Xeon's was $311, but the decision should rest on workload: pick the i9 for raw multi-core desktop performance, pick the Xeon for single-thread sensitivity and server-grade features.