Intel Core i3-8109U vs Intel Core i3-8121U Comparison

FAQ

Q: Which processor has the higher boost clock, and by how much?

A: The Intel Core i3-8109U boosts to 3.60 GHz, which is 0.40 GHz higher than the Intel Core i3-8121U's 3.20 GHz boost. The 8109U also has a higher base clock at 3.00 GHz versus 2.20 GHz.

Q: Does the i3-8121U have integrated graphics?

A: No, the database lists the i3-8121U with no integrated graphics. The i3-8109U, in contrast, includes Iris Pro Plus integrated graphics, which is a significant feature difference for systems without a discrete GPU.

Q: Which chip has the better multi-core Cinebench R23 score?

A: The i3-8121U edges ahead with a Cinebench R23 multi-core score of 3637 versus 3544 for the i3-8109U, a 2.6% difference. However, the i3-8109U wins in Geekbench multi-core with 2454 against 2215, a 10.8% margin.

Q: Are these processors the same in terms of core and thread counts?

A: Yes, both have 2 cores and 4 threads. They also share identical L1 cache (64 KB per core), L2 cache (256 KB per core), and L3 cache (4 MB shared). Both support DDR4 memory and do not support ECC memory.

Q: What is the manufacturing node difference?

A: The i3-8109U is built on Intel's 14 nm process with a die size of 123 mm². The i3-8121U uses Intel's 10 nm process with a die size of 70.52 mm², making it a smaller and newer fabrication node.

Q: Which processor has the higher single-core Cinebench R15 score?

A: The i3-8109U dominates this specific test with a score of 138.65 versus just 51 for the i3-8121U, representing a 171.9% advantage. This is an outlier compared to other single-core results where the gap is much smaller.

Architecture Differences

The two chips share a common heritage in Intel's Core i3 lineup, but their underlying architectures diverge significantly. The i3-8109U is based on Kaby Lake, specifically the Kaby Lake-R refresh, fabricated on Intel's 14 nm process. The i3-8121U, however, is built on Cannon Lake, which marks Intel's first generation on the 10 nm node. This architectural shift is reflected in the die sizes: the 8109U measures 123 mm², while the 8121U comes in at a more compact 70.52 mm².

Despite the node difference, both processors maintain identical cache hierarchies: 64 KB of L1 per core, 256 KB of L2 per core, and 4 MB of shared L3 cache. Neither chip supports ECC memory, and both are unlocked from a multiplier perspective, though neither has an unlocked multiplier. The memory support is DDR4 for both, but the 8121U is the only one with a specified memory bus (dual-channel) and a quantified memory bandwidth of 38.4 GB/s. The 8121U also explicitly lists PCIe Gen 3 with 16 lanes (CPU only), a detail absent for the 8109U.

Integrated graphics present a major differentiator: the 8109U includes Iris Pro Plus, while the 8121U has no integrated graphics at all. This makes the 8121U dependent on a discrete GPU, whereas the 8109U can operate in thinner, lighter systems without one. The socket types also differ, with the 8109U using Intel BGA 1356 and the 8121U using Intel BGA 1440, meaning they are not drop-in interchangeable on the same motherboard.

The production status also differs: the 8109U is listed as Active, while the 8121U is End-of-life. The release dates are close, with the 8109U launching on April 4, 2018, and the 8121U on May 4, 2018. The 8121U has a part number (SRCVC) recorded, while the 8109U does not. The TDP gap is notable: 28 watts for the 8109U versus 15 watts for the 8121U, which has implications for thermal design and battery life in portable systems.

Head-to-Head Benchmarks

The benchmark data reveals a split personality between these two processors. The i3-8121U wins the majority of the head-to-head tests, claiming 5 of the 8 comparisons, but the margins are often narrow. In Cinebench R15 multi-core, the 8121U scores 366 versus 357 for the 8109U, a 2.5% lead. The R20 multi-core test shows 1527 against 1488, a 2.6% edge. The R23 multi-core follows the same pattern: 3637 versus 3544, again a 2.6% difference. Even in Cinebench R20 single-core, the 8121U manages a slim win: 215 versus 210, a 2.3% margin. The R23 single-core goes similarly, with 513 against 500, a 2.5% lead.

The i3-8109U, however, secures decisive victories in other tests. The Geekbench multi-core score is 2454 against 2215, a substantial 10.8% advantage. The Geekbench single-core score is 1188 versus 1149, a 3.4% lead. The most striking result is the Cinebench R15 single-core test, where the 8109U scores 138.65 against a mere 51 for the 8121U. That is a 171.9% difference, which is so anomalous that it suggests either a measurement anomaly or a very specific workload condition. The database records this as a win for the 8109U, but the magnitude is far outside the pattern of other single-core tests.

Interpreting these results requires caution. The Cinebench family of tests generally favors the 8121U, while the Geekbench suite favors the 8109U. The average benchmark scores reflect this: the 8109U has an average score of 1235, while the 8121U sits at 1209. Both processors occupy the 34th percentile among all CPUs, indicating they are in the same performance tier overall. The nearest rivals for the 8109U include the Intel Pentium Gold G6600 at an identical average score of 1235, the Intel Core i7-3610QM at 1244, and the Intel Core i5-2500 at 1220. The 8121U's nearest rivals include the Intel Xeon D-1520 at 1209, the Intel Xeon E5645 at 1211, and the Intel Core i3-7300T at 1211. This places both chips in similar company, despite their architectural differences.

The Verdict

The data suggests that neither processor is a clear overall winner, and the choice depends heavily on the intended workload. The i3-8121U has the edge in Cinebench multi-core tests, winning all three versions by roughly 2.5% to 2.6%. It also wins Cinebench R20 and R23 single-core by similar margins. If the primary use case involves rendering or CPU-heavy multi-threaded tasks as measured by Cinebench, the 8121U is the better pick.

The i3-8109U, however, wins in Geekbench multi-core by a substantial 10.8% and in Geekbench single-core by 3.4%. It also has the vast Cinebench R15 single-core lead of 171.9%, although this result is so skewed that it should be weighted cautiously. For general computing tasks, system responsiveness, or workloads that align with Geekbench's methodology, the 8109U appears stronger.

The average benchmark scores tilt slightly toward the 8109U: 1235 versus 1209, a difference of about 2.1%. Both sit at the 34th percentile, meaning they are comparable to a broad swath of CPUs in the database. The 8109U also carries the advantage of integrated graphics, which makes it a more self-contained solution for laptops without discrete GPUs. The 8121U, with its lower 15-watt TDP, is the more power-efficient option, but it requires a separate graphics solution.

For buyers, the 8109U is the safer all-around choice for mobile systems where integrated graphics matter and where Geekbench-style workloads dominate. The 8121U is the pick for those prioritizing Cinebench multi-core performance and lower power consumption, provided a discrete GPU is already planned. The 8109U remains in active production, while the 8121U is end-of-life, which may affect long-term availability and driver support.

Specification Differences

The two processors differ in several key specifications. The base clock is 3.00 GHz for the 8109U versus 2.20 GHz for the 8121U. The boost clock is 3.60 GHz versus 3.20 GHz. The TDP is 28 watts for the 8109U and 15 watts for the 8121U. The socket is Intel BGA 1356 for the 8109U and Intel BGA 1440 for the 8121U. The architecture is Kaby Lake for the 8109U and Cannon Lake for the 8121U, with corresponding codenames of Kaby Lake-R and Cannon Lake. The process node is 14 nm for the 8109U and 10 nm for the 8121U. The die size is 123 mm² for the 8109U and 70.52 mm² for the 8121U.

The 8109U has Iris Pro Plus integrated graphics, while the 8121U has none. The 8121U specifies a dual-channel memory bus and 38.4 GB/s memory bandwidth, details not recorded for the 8109U. The 8121U also lists PCIe Gen 3 with 16 lanes (CPU only), while the 8109U has no PCIe information. The production status is Active for the 8109U and End-of-life for the 8121U. The 8121U has a part number (SRCVC), while the 8109U does not. Both have identical cache sizes, core and thread counts, memory support type (DDR4), and ECC capability (false). Neither has a launch MSRP recorded in the database.

Where Each One Wins

The i3-8109U wins in Geekbench multi-core (2454 versus 2215, a 10.8% advantage) and Geekbench single-core (1188 versus 1149, a 3.4% advantage). It also wins the Cinebench R15 single-core test by an enormous margin (138.65 versus 51, a 171.9% lead), though the reliability of this specific result is questionable given its outlier nature. The 8109U also carries integrated graphics, making it the better choice for systems without a dedicated GPU. Its higher base and boost clocks (3.00 GHz and 3.60 GHz) suggest better responsiveness in clock-sensitive workloads, which aligns with its Geekbench single-core win.

The i3-8121U wins in all three Cinebench multi-core tests: R15 (366 versus 357, a 2.5% lead), R20 (1527 versus 1488, a 2.6% lead), and R23 (3637 versus 3544, a 2.6% lead). It also wins in Cinebench R20 single-core (215 versus 210, a 2.3% lead) and Cinebench R23 single-core (513 versus 500, a 2.5% lead). The 8121U's lower 15-watt TDP makes it the more power-efficient option, which is advantageous in thermally constrained laptops. Its 10 nm process node and smaller die size (70.52 mm²) indicate a more modern manufacturing approach, and its explicit dual-channel memory support with 38.4 GB/s bandwidth may benefit memory-sensitive applications.

The overall win count favors the 8121U at 5 wins versus 3 for the 8109U, but the average benchmark score favors the 8109U (1235 versus 1209). This divergence suggests the 8121U excels in the Cinebench family while the 8109U dominates Geekbench. Use-case selection should follow these benchmark patterns: Cinebench-heavy workloads (rendering, multi-threaded content creation) lean toward the 8121U, while general productivity, system responsiveness, and Geekbench-aligned tasks favor the 8109U. The 8109U's integrated graphics also make it the more versatile option for everyday mobile use, while the 8121U's end-of-life status and lack of graphics limit its appeal for new designs.