Core 2 Quad Q8400 vs Core 2 Duo SP9400

The Core 2 Quad Q8400 packs 4 cores / 4 threads, while the Core 2 Duo SP9400 offers 2 cores / 2 threads — the Core 2 Quad Q8400 has 2 more cores. Boost clocks reach 0.67 GHz on the Core 2 Quad Q8400 versus 2.4 GHz on the Core 2 Duo SP9400 — a 112.7% clock advantage for the Core 2 Duo SP9400 (base: 2.66 GHz vs 2.4 GHz). The Core 2 Quad Q8400 uses the Yorkfield (2007−2009) architecture (45 nm), while the Core 2 Duo SP9400 uses Penryn (2008−2011) (45 nm). In PassMark, the Core 2 Quad Q8400 scores 2,076 against the Core 2 Duo SP9400's 2,083 — a 0.3% lead for the Core 2 Duo SP9400. Geekbench 6 single-core — the metric most relevant to gaming — records 369 vs 340, a 8.2% lead for the Core 2 Quad Q8400 that directly translates to higher frame rates. Multi-core Geekbench: 1,155 vs 600 (63.2% advantage for the Core 2 Quad Q8400). L3 cache: 0 kB on the Core 2 Quad Q8400 vs 6 MB L2 Cache on the Core 2 Duo SP9400.

The Core 2 Quad Q8400 uses the LGA775 socket (PCIe 1.1), while the Core 2 Duo SP9400 uses BGA956 (PCIe 1.1) — making them incompatible on the same motherboard. Maximum memory speed reaches DDR3 1333 MHz on the Core 2 Quad Q8400 versus DDR3-1066 on the Core 2 Duo SP9400 — the Core 2 Quad Q8400 supports 200% faster memory, which can translate to measurable gains in memory-sensitive workloads. The Core 2 Quad Q8400 supports up to 16 GB of RAM compared to 8 GB — 66.7% more capacity for professional workloads. Both feature 2-channel memory with ECC support. Chipset compatibility: Intel P45,Intel G41,Intel Q45,Intel X48,Intel G31 (Core 2 Quad Q8400) and GS45 (Core 2 Duo SP9400).

Neither processor supports overclocking. Virtualization support: true (Core 2 Quad Q8400) vs VT-x (Core 2 Duo SP9400). Primary use case: Core 2 Quad Q8400 targets Desktop, Core 2 Duo SP9400 targets Budget. Direct competitor: Core 2 Duo SP9400 rivals Athlon II X2 245e.