Processors/Comparison
15 specifications
Intel Core i5-2500K vs Intel Core i5-6600K
On paper, the Intel Core i5-6600K boosts higher. Specifications describe what each chip is designed to do; how much of that either one holds under continuous load is a separate question.
Intel Core i5-2500K
Intel · Core 2nd generation · Desktop
Intel Core i5-6600K
Intel · Core 6th generation · Desktop
Cores and clocks
Cache and power
Platform
A check marks the higher figure only on rows where higher is unambiguously better. Rows without one are not ties; they are specifications where “better” has no meaning.
Reading the table
What the difference means.
Boost clock
The Core i5-6600K boosts to 3.9 GHz against 3.7 GHz, 5 percent higher. Across generations it is not a guide to speed on its own, for the reason above. Boost is also a peak: it is held for seconds to minutes, on one or two cores, while the cooling and the power limit allow. What either chip settles at under a long load is lower, and it depends on the cooler and the motherboard as much as the chip.
Power and cooling
The Core i5-2500K is rated at 95 W against 91 W. The rating is the heat the cooler has to move for the chip to hold its speed, and modern chips draw well above it in short bursts. A competent tower cooler suits the Core i5-2500K; the Core i5-6600K is easier to keep quiet and fits smaller cases. A chip whose cooling falls short does not fail. It slows down, and it does so after the first minute, which is why short benchmarks miss it.
Platform
They use different sockets, LGA1155 and FCLGA1151, so moving from one to the other means a new motherboard. For an upgrade, that cost belongs in the comparison; for a new build, the newer platform is the one with later chips still to come.
Manufacturing process
The Core i5-6600K is built on a 14 nm process against 32 nm. A finer process generally does the same work for less power. The names are marketing labels rather than measurements, though, and they are not comparable between manufacturers, so treat the row as a sign of how recent the design is and no more.
Which to pick, on paper
- A quiet or compact build
- Core i5-6600K
- 91 W against 95 W: less heat to move, so a smaller cooler and slower fans.
What no table says
How much of its speed a processor keeps after the first minute depends on the cooling and the power limit of the machine it is in. If you own one of these, measure it: the test is free and runs in this browser.
Questions
- Is the Core i5-2500K better than the Core i5-6600K?
- By need, on the specifications: a quiet or compact build: the Core i5-6600K. No specification says how much speed either one keeps under a long load; that depends on the cooling and the power limit of the machine it is in, and it is what a sustained test measures.
- Do the Core i5-2500K and the Core i5-6600K use the same socket?
- No. The Core i5-2500K uses LGA1155 and the Core i5-6600K uses FCLGA1151, so switching means a new motherboard.
- Does the Core i5-2500K or the Core i5-6600K have integrated graphics?
- Both do: Intel HD Graphics 3000 on the Core i5-2500K and Intel HD Graphics 530 on the Core i5-6600K.
- Which runs hotter, the Core i5-2500K or the Core i5-6600K?
- The Core i5-2500K is rated at 95 W against 91 W, so it produces more heat under load and needs the larger cooler. How hot either one actually runs depends on the cooler and the case more than on the chip.
More comparisons
- Intel Core i5-2500K vs AMD FX-4100
- Intel Core i5-2500K vs Intel Core i5-4690
- Intel Core i5-2500K vs Intel Core i5-6600
- Intel Core i5-2500K vs AMD Ryzen 3 1200
- Intel Core i5-2500K vs AMD Ryzen 5 1400
- Intel Core i5-6600K vs Intel Core i5-4690
- Intel Core i5-6600K vs Intel Core i5-6600
- Intel Core i5-6600K vs AMD FX-4100
- Intel Core i5-6600K vs Intel Core i7-4770
- Intel Core i5-6600K vs Intel Core i7-4770K
- Intel Core i5-6600K vs AMD A8-6600K with Radeon HD 8570D
Every figure on this table is a design target. None of it is a measurement.
Nothing above describes how a processor behaves twenty minutes into a sustained workload, which is where two chips with nearly identical specifications routinely diverge. A boost clock is a ceiling the vendor permits, not a rate the chip sustains, and whether it holds depends on the cooling, the case, the power profile and the room. None of those appear on a specification sheet.
We deliberately do not reduce these figures to a single score. A composite invented from specifications would look authoritative and measure nothing, and choosing the weights would be choosing the winner.