Core i5-3475S vs Core i3-8121U

The Core i5-3475S packs 4 cores / 4 threads, while the Core i3-8121U offers 2 cores / 4 threads — the Core i5-3475S has 2 more cores. Boost clocks reach 3.6 GHz on the Core i5-3475S versus 3.2 GHz on the Core i3-8121U — a 11.8% clock advantage for the Core i5-3475S (base: 2.9 GHz vs 2.2 GHz). The Core i5-3475S uses the Ivy Bridge (2012−2013) architecture (22 nm), while the Core i3-8121U uses Coffee Lake-U (2018−2019) (10 nm). In PassMark, the Core i5-3475S scores 4,315 against the Core i3-8121U's 4,271 — a 1% lead for the Core i5-3475S. Geekbench 6 single-core — the metric most relevant to gaming — records 705 vs 1,178, a 50.2% lead for the Core i3-8121U that directly translates to higher frame rates. Multi-core Geekbench: 1,544 vs 2,250 (37.2% advantage for the Core i3-8121U). L3 cache: 6 MB (total) on the Core i5-3475S vs 4 MB (total) on the Core i3-8121U.

The Core i5-3475S uses the LGA1155 socket (PCIe 3.0), while the Core i3-8121U uses BGA1440 (PCIe 3.0) — making them incompatible on the same motherboard. Maximum memory speed reaches DDR3-1600 on the Core i5-3475S versus DDR4-2400 on the Core i3-8121U — the Core i3-8121U supports 28.6% faster memory, which can translate to measurable gains in memory-sensitive workloads. Both support up to 32 GB of RAM. Both feature 2-channel memory with ECC support. Both provide 16 PCIe lanes. Chipset compatibility: H61,B75,H77,Z75,Z77 (Core i5-3475S) and SoC (Core i3-8121U).

Neither processor supports overclocking. Only the Core i3-8121U supports AVX-512 instructions — important for machine learning and scientific applications. Both support VT-x, VT-d, EPT virtualization. The Core i5-3475S includes integrated graphics (HD Graphics 4000), while the Core i3-8121U requires a dedicated GPU. Primary use case: Core i5-3475S targets Budget, Core i3-8121U targets Productivity. Direct competitor: Core i5-3475S rivals FX-6300; Core i3-8121U rivals Core i3-8130U.