Intel Core i9-12900E vs Intel Core i9-9940X Comparison

Head-to-Head Benchmarks

The benchmark data presents a surprisingly consistent picture across most tests, with the Intel Core i9-9940X taking seven of eight head-to-head wins. In Cinebench R15, the 9940X scores 2400 versus 2371 for the 12900E in multi-core, a 1.2% margin, and edges out the 12900E in single-core by the same 1.2% (338 vs 334). The pattern holds in Cinebench R20, where the 9940X posts 10000 against 9882 multi-core and 1411 against 1394 single-core, again a 1.2% advantage. Cinebench R23 shows the same narrow lead: 23810 vs 23529 multi-core and 3361 vs 3321 single-core, all at exactly 1.2% delta.

Geekbench multi-core follows suit with the 9940X at 10466 versus 10280, a slightly larger 1.8% gap. The one decisive reversal comes in Geekbench single-core, where the 12900E delivers 1775 against the 9940X's 1468 — a 17.3% swing in favor of the newer chip. That is a substantial margin, not a rounding error, and it signals a fundamental difference in how each processor handles lightly threaded workloads.

Looking at average benchmark scores, the 9940X sits at 6657 and the 12900E at 6611, placing both in the 62nd percentile of all CPUs. The nearest-rival data reinforces how close these two are overall: the 9940X is 0.7% ahead of the 12900E, while the 12900E is 0.4% behind the Intel Core i5-13400E and 0.1% ahead of both the Intel Core i9-10940X and the Intel Pentium Gold G6405. For context, the 9940X's closest competitor, the AMD Ryzen Threadripper 2950X, sits just 0.1% behind it. These are all tightly clustered results, but the head-to-head numbers show the 9940X winning every Cinebench iteration by an identical 1.2% — a remarkably consistent margin that suggests a stable architectural advantage in that workload.

Architecture Differences

The two CPUs come from different design eras and philosophies. The 9940X uses the Skylake-X architecture on a 14 nm process, with a die size of 484 mm². It has 14 cores and 28 threads, with a base clock of 3.30 GHz and a boost clock of 4.50 GHz. The 12900E uses Alder Lake-S on a 10 nm process, with a smaller 215 mm² die. It packs 16 cores but only 24 threads, indicating a hybrid design that relies on efficiency cores without hyper-threading on all of them. Its base clock drops to 2.30 GHz, but the boost clock rises to 5.00 GHz.

Cache layouts differ substantially. The 9940X allocates 64 KB of L1 per core, 1 MB of L2 per core, and 19.25 MB of shared L3. The 12900E uses 80 KB of L1 per core, 1.25 MB of L2 per core, and 30 MB of shared L3. The larger L3 on the 12900E is notable, as is the smaller die size — less than half the physical area of the 9940X.

Memory support splits them further. The 9940X runs DDR4 on a quad-channel bus, delivering 85.3 GB/s of memory bandwidth. The 12900E supports both DDR4 and DDR5, but uses a dual-channel bus, with no bandwidth figure listed. PCIe connectivity also differs: the 9940X offers Gen 3 with 44 CPU lanes, while the 12900E provides Gen 5 with 20 CPU lanes. The 12900E includes integrated graphics (UHD Graphics 770), whereas the 9940X has none. Both are unlocked for overclocking, and neither supports ECC memory.

The sockets and platforms are completely incompatible. The 9940X uses Intel Socket 2066, the 12900E uses Intel Socket 1700. The 9940X is end-of-life, released in 2018, while the 12900E is active, released in 2022. TDP tells a stark story: the 9940X draws 165 W, the 12900E just 65 W.

FAQ

Q: Which CPU wins more benchmark tests?

A: The Intel Core i9-9940X wins seven of eight head-to-head tests, including all six Cinebench R15, R20, and R23 runs, plus Geekbench multi-core. The Intel Core i9-12900E wins only Geekbench single-core.

Q: How large is the single-core performance gap?

A: In Geekbench single-core, the 12900E scores 1775 versus 1468 for the 9940X, a 17.3% advantage. That is the only test where the delta exceeds 1.8%, making it the standout difference between the two.

Q: Are these CPUs similar in overall performance?

A: Yes. The 9940X has an average benchmark score of 6657, and the 12900E sits at 6611. The 9940X is 0.7% ahead of the 12900E in the nearest-rivals comparison, and both rank in the 62nd percentile of all CPUs.

Q: What are the core and thread counts?

A: The 9940X has 14 cores and 28 threads. The 12900E has 16 cores but only 24 threads, meaning it has more physical cores yet fewer threads overall.

Q: Do they use the same memory configuration?

A: No. The 9940X uses quad-channel DDR4 with 85.3 GB/s bandwidth. The 12900E uses dual-channel DDR4 or DDR5, with no bandwidth figure provided.

Q: Which CPU has integrated graphics?

A: Only the 12900E, which includes UHD Graphics 770. The 9940X has no integrated graphics, so it requires a discrete GPU for display output.

Specification Differences

| Specification | Intel Core i9-9940X | Intel Core i9-12900E |

|---|---|---|

| Cores | 14 | 16 |

| Threads | 28 | 24 |

| Base Clock | 3.30 GHz | 2.30 GHz |

| Boost Clock | 4.50 GHz | 5.00 GHz |

| TDP | 165 W | 65 W |

| Socket | Intel Socket 2066 | Intel Socket 1700 |

| Architecture | Skylake | Alder Lake |

| Process Node | 14 nm | 10 nm |

| Die Size | 484 mm² | 215 mm² |

| L1 Cache | 64 KB (per core) | 80 KB (per core) |

| L2 Cache | 1 MB (per core) | 1.25 MB (per core) |

| L3 Cache | 19.25 MB (shared) | 30 MB (shared) |

| Memory Support | DDR4 | DDR4, DDR5 |

| Memory Bus | Quad-channel | Dual-channel |

| Memory Bandwidth | 85.3 GB/s | Not listed |

| PCIe | Gen 3, 44 Lanes | Gen 5, 20 Lanes |

| Integrated Graphics | None | UHD Graphics 770 |

| Production Status | End-of-life | Active |

| Release Date | 2018-10-18 | 2022-01-03 |

| Part Number | SREZ5 | SRL6B |

The Verdict

The data points to a clear split based on workload type. The 9940X holds a narrow but consistent lead in every Cinebench test, winning multi-core and single-core alike by 1.2%. It also wins Geekbench multi-core by 1.8%. If your work is heavily threaded rendering or encoding, the 9940X is the safer pick based on raw scores alone. However, the 12900E crushes it in Geekbench single-core with a 17.3% margin, which points to substantially better per-thread performance in that specific test.

The 12900E also offers practical advantages that the benchmark scores do not capture. It has a 65 W TDP versus 165 W, a much smaller die, and active production status. The 9940X is end-of-life. For a new build, the 12900E's modern platform with DDR5 support and integrated graphics makes it easier to live with day to day. The 9940X's quad-channel memory and 44 PCIe Gen 3 lanes are legacy strengths, but they come at a cost in power and platform longevity.

Consider the launch MSRP: the 9940X was $1387, while the 12900E was $494. That difference is not a performance recommendation by itself, but it contextualizes the 9940X as a premium HEDT part from 2018 and the 12900E as a mainstream part from 2022. The average benchmark scores differ by only 0.7%, so the 9940X's historical price premium bought a modest overall advantage.

Where Each One Wins

Intel Core i9-9940X: Choose this for multi-threaded rendering and encoding workloads where Cinebench scores matter most. It wins every Cinebench R15, R20, and R23 test, albeit by a slim 1.2% margin. Its quad-channel memory bus and 44 PCIe Gen 3 lanes also suit workstation-style configurations that need high memory bandwidth and many expansion slots. If you already own a Socket 2066 platform, the 9940X's 28 threads and 7-of-8 benchmark wins justify keeping it in service.

Intel Core i9-12900E: Choose this for lightly threaded applications and general desktop use where Geekbench single-core performance translates to real-world responsiveness. The 17.3% lead in that test is the largest gap between the two chips by a wide margin. Its 16 cores and 30 MB of L3 cache provide strong multi-threaded output close to the 9940X, while the 65 W TDP makes it far easier to cool and power. The integrated UHD Graphics 770 means it can run without a discrete GPU for basic tasks, and DDR5 support future-proofs the memory subsystem. Active production status and a modern Socket 1700 platform make it the more practical long-term choice.