Core i5-2500K vs Core i5-6400T

Both the Core i5-2500K and Core i5-6400T share an identical 4-core/4-thread configuration. Boost clocks reach 3.7 GHz on the Core i5-2500K versus 2.8 GHz on the Core i5-6400T — a 27.7% clock advantage for the Core i5-2500K (base: 3.3 GHz vs 2.2 GHz). The Core i5-2500K uses the Sandy Bridge (2011−2013) architecture (32 nm), while the Core i5-6400T uses Skylake (2015−2016) (14 nm). In PassMark, the Core i5-2500K scores 4,141 against the Core i5-6400T's 4,243 — a 2.4% lead for the Core i5-6400T. Cinebench R23 multi-core: 3,200 vs 2,200 (37% advantage for the Core i5-2500K). Geekbench 6 single-core — the metric most relevant to gaming — records 684 vs 950, a 32.6% lead for the Core i5-6400T that directly translates to higher frame rates. Multi-core Geekbench: 2,032 vs 2,600 (24.5% advantage for the Core i5-6400T). L3 cache: 6 MB (total) on the Core i5-2500K vs 6 MB on the Core i5-6400T.

The Core i5-2500K uses the LGA1155 socket (PCIe 2.0), while the Core i5-6400T uses LGA1151 (PCIe 3.0) — making them incompatible on the same motherboard. Maximum memory speed reaches DDR3-1333 on the Core i5-2500K versus DDR4-2133 on the Core i5-6400T — the Core i5-6400T supports 28.6% faster memory, which can translate to measurable gains in memory-sensitive workloads. The Core i5-6400T supports up to 64 GB of RAM compared to 32 GB — 66.7% more capacity for professional workloads. Both feature 2-channel memory with ECC support. Both provide 16 PCIe lanes. Chipset compatibility: P67,Z68,Z77 (Core i5-2500K) and H110,B150,H170,Z170,Z270 (Core i5-6400T).

Only the Core i5-2500K has an unlocked multiplier for overclocking — a significant advantage for enthusiasts seeking extra performance. Virtualization support: VT-x (Core i5-2500K) vs VT-x, VT-d (Core i5-6400T). Both include integrated graphics — HD Graphics 3000 (Core i5-2500K) and HD 530 (Core i5-6400T) — useful as a fallback for troubleshooting or display output without a dedicated GPU. Primary use case: Core i5-2500K targets Gaming, Core i5-6400T targets Budget. Direct competitor: Core i5-2500K rivals FX-6300; Core i5-6400T rivals Core i3-7100.

The Core i5-2500K launched at $225 MSRP, while the Core i5-6400T debuted at $192. At current prices ($35 vs $40), the Core i5-2500K is $5 cheaper. In terms of value (PassMark points per dollar), the Core i5-2500K delivers 118.3 pts/$ vs 106.1 pts/$ for the Core i5-6400T — making the Core i5-2500K the 10.9% better value option.