Intel Core i9-7900X vs Intel Core i9-9820X Comparison

The Intel Core i9-7900X and Intel Core i9-9820X are near-identical on paper, but benchmark data shows the older 7th Gen part consistently edges out its 9th Gen successor. In six head-to-head Cinebench tests, the i9-7900X wins every single one, with margins ranging from 1.2% to 1.4%. Both processors share the same 10-core, 20-thread configuration, 14 nm process, and Skylake-X architecture, but the i9-7900X’s higher 4.50 GHz boost clock and its smaller 14 MB L3 cache prove decisive. The i9-9820X does counter with a larger 16.5 MB L3 cache and a lower launch MSRP, but it cannot translate those advantages into a single benchmark victory.

FAQ

Q: Which CPU is faster in multi-core workloads?

A: The Intel Core i9-7900X wins all three multi-core Cinebench tests. It scores 1782 in R15, 7425 in R20, and 17680 in R23, versus the i9-9820X’s 1759, 7332, and 17459 respectively. The largest multi-core margin is 1.3% in both R15 and R20.

Q: Is there any single-core performance difference?

A: Yes, the i9-7900X leads in every single-core test. It scores 251 in R15, 1048 in R20, and 2496 in R23. The i9-9820X trails with 248, 1034, and 2464. The biggest single-core gap is 1.4% in Cinebench R20.

Q: Do both CPUs have the same core and thread counts?

A: Yes, both processors feature exactly 10 cores and 20 threads. This identical configuration means the benchmark differences stem from clock speeds and cache design rather than core count.

Q: How do their cache sizes compare?

A: The i9-7900X has 64 KB of L1 per core, 1 MB of L2 per core, and 14 MB of shared L3 cache. The i9-9820X has the same L1 and L2 per core but a larger 16.5 MB of shared L3 cache, giving it 2.5 MB more total L3.

Q: Which CPU has a higher boost clock?

A: The i9-7900X boosts to 4.50 GHz, while the i9-9820X tops out at 4.20 GHz. The i9-7900X’s 0.30 GHz advantage aligns with its consistent single-core wins.

Q: What are the launch prices for each?

A: The i9-7900X had a launch MSRP of $999, while the i9-9820X launched at $889. The i9-9820X is the lower-priced part at launch, despite arriving later.

The Verdict

The data points to a clear, if narrow, verdict: the Intel Core i9-7900X is the superior processor for raw performance. It wins 6 out of 6 head-to-head benchmarks, with every victory falling between 1.2% and 1.4%. This consistency across all Cinebench versions—R15, R20, and R23—indicates a fundamental performance edge, not a workload-specific anomaly. The i9-7900X’s higher boost clock of 4.50 GHz versus 4.20 GHz on the i9-9820X is the likely driver, translating directly into both single-core and multi-core dominance.

For users prioritizing maximum benchmark scores, the i9-7900X is the unambiguous choice. Its 17680 Cinebench R23 multi-core score and 2496 single-core score are the highest figures in this comparison. However, the i9-9820X is not without merit. Its 16.5 MB L3 cache is 2.5 MB larger, and it launched at $889, which is $110 less than the i9-7900X’s $999 launch MSRP. If cache capacity or launch price are critical factors, the i9-9820X offers a slight structural advantage, but it cannot overcome the performance deficit in any benchmark test.

The verdict is straightforward: the i9-7900X wins on performance, period. The i9-9820X is the alternative for those who value a larger L3 cache and a lower launch price, accepting a 1.2% to 1.4% performance penalty.

Head-to-Head Benchmarks

The head-to-head data shows a clean sweep for the Intel Core i9-7900X. In Cinebench R15 multi-core, the i9-7900X scores 1782 against 1759 for the i9-9820X, a 1.3% lead. The single-core R15 test is closer, 251 versus 248, for a 1.2% margin. Moving to Cinebench R20, the i9-7900X posts 7425 multi-core and 1048 single-core, while the i9-9820X manages 7332 and 1034. These differences translate to 1.3% and 1.4% deltas, respectively—the largest single-core gap in the entire comparison.

The most recent Cinebench R23 results reinforce the pattern. The i9-7900X scores 17680 multi-core and 2496 single-core, beating the i9-9820X’s 17459 and 2464. Both R23 deltas sit at exactly 1.3%. Notably, the i9-9820X never wins a single test, and its closest performance is in R15 single-core, where it trails by only 3 points. The average benchmark score further confirms the hierarchy: the i9-7900X holds an average of 5120, while the i9-9820X averages 5049.

The margins are small but uniform. Every multi-core test shows a 1.3% delta, and every single-core test falls between 1.2% and 1.4%. This consistency suggests the i9-7900X’s clock speed advantage is the sole differentiator, as both chips share identical core counts, threads, and process node.

Specification Differences

The core specifications are largely identical, but three fields differ. The most impactful is the boost clock: the i9-7900X reaches 4.50 GHz, while the i9-9820X peaks at 4.20 GHz. This 0.30 GHz difference is the primary driver of the i9-7900X’s benchmark sweep. The base clocks are the same at 3.30 GHz for both.

The L3 cache also differs. The i9-7900X has 14 MB shared, while the i9-9820X has 16.5 MB shared—a 2.5 MB advantage for the newer part. Both share the same L1 (64 KB per core) and L2 (1 MB per core) caches.

The thermal design power (TDP) is another distinction. The i9-7900X is rated at 140 W, whereas the i9-9820X draws 165 W. This means the i9-9820X consumes more power despite delivering lower performance. The launch MSRP also differs: the i9-7900X was $999, and the i9-9820X was $889. The part numbers and release dates round out the differences, with the i9-7900X being SR3L2 released on 2017-06-25, and the i9-9820X being SREZ8 released on 2018-10-18.

Architecture Differences

Both processors share the same fundamental architecture: Skylake, specifically the Skylake-X codename, built on Intel’s 14 nm process. Both are desktop parts using the Intel Socket 2066 and support DDR4 memory over a quad-channel bus with 85.3 GB/s bandwidth. Neither supports ECC memory, and both offer PCIe Gen 3 with 44 lanes from the CPU.

The generation labels differ, though the silicon is nearly identical. The i9-7900X is classified as Core i9 X-Series 7th Gen, while the i9-9820X is Core i9 X-Series 9th Gen. This generational naming does not translate into architectural improvements in the benchmark data. The cache hierarchy is the only structural difference: the i9-9820X adds 2.5 MB of shared L3 cache, bringing its total to 16.5 MB versus 14 MB on the i9-7900X. Both chips have unlocked multipliers, and neither includes integrated graphics. Both are end-of-life products, with the i9-7900X using part number SR3L2 and the i9-9820X using SREZ8.

Where Each One Wins

The Intel Core i9-7900X wins in every measurable performance category. It is the choice for any workload where benchmark scores matter, including multi-threaded rendering, video encoding, and heavy compilation tasks. Its 17680 Cinebench R23 multi-core score is the highest in this comparison, and its single-core scores are similarly superior. The i9-7900X also wins on power efficiency, with a 140 W TDP versus 165 W for the i9-9820X, meaning it achieves higher scores while drawing less power.

The Intel Core i9-9820X has no benchmark wins, but it does hold advantages in two non-performance areas. Its 16.5 MB L3 cache is larger, which could theoretically benefit workloads with high cache reuse, though the data does not show any test where this translates into a win. It also launched at a lower MSRP of $889 versus $999 for the i9-7900X, making it the more affordable option at launch. For users who prioritize cache capacity or launch price over raw benchmark output, the i9-9820X is the only logical pick. For everyone else, the i9-7900X is the definitive winner across all six head-to-head tests.