Processors/Comparison
15 specifications
Intel Core i3-14100F vs Intel Core i5-8400
On paper, the Intel Core i5-8400 has more cores (6 against 4), the Intel Core i3-14100F boosts higher, and the Intel Core i3-14100F carries more L3 cache. 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 i3-14100F
Intel · Raptor Lake Refresh (14th gen) · Desktop
Intel Core i5-8400
Intel · Coffee Lake (8th gen) · 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.
7 years apart
The Core i3-14100F (Raptor Lake Refresh (14th gen), 2024) is 7 years newer than the Core i5-8400 (Coffee Lake (8th gen), 2017). That matters more than any single row in the table, because a newer design usually does more work in each clock cycle. Clock speeds are only a fair comparison between chips of the same generation; across a gap this wide, a lower number on the newer chip can still be the faster core.
Cores and threads
This pair splits: the Core i5-8400 has more cores (6 against 4) while the Core i3-14100F runs more threads (8 against 6). That happens when one design runs two threads on every core and the other does not, or mixes large and small cores. A second thread on a core adds roughly a quarter to a third of a core's work, not a whole one, so 6 full cores and 8 threads on 4 cores land closer together than either number suggests. Work that spreads across everything, such as rendering, compiling and video export, is where the difference shows; which side wins it depends on how fast each core is, which a specification sheet does not say.
Boost clock
The Core i3-14100F boosts to 4.7 GHz against 4 GHz, 18 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.
Cache
The Core i3-14100F carries 12 MB of L3 cache against 9 MB. Cache is fast memory on the chip, and a larger one means the cores wait on main memory less often. Games, large spreadsheets and compiling respond to it; rendering and video export, which stream through data in order, respond much less.
Power and cooling
The Core i5-8400 is rated at 65 W against 58 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 i5-8400; the Core i3-14100F 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, FCLGA1700 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.
Graphics on the chip
The Core i5-8400 includes Intel UHD Graphics 630; the Core i3-14100F has no graphics of its own and will not show a picture without a graphics card. For a build with a card that changes nothing. For an office machine, a home server, or while waiting for a card, it decides the question.
Which to pick, on paper
- Rendering, compiling, video export
- Core i3-14100F
- 8 threads against 6. Work that uses every thread scales with how many there are.
- A quiet or compact build
- Core i3-14100F
- 58 W against 65 W: less heat to move, so a smaller cooler and slower fans.
- No graphics card
- Core i5-8400
- It has Intel UHD Graphics 630 on the chip. The other needs a card to display anything.
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 i3-14100F better than the Core i5-8400?
- The Core i3-14100F is the newer design by 7 years, which usually means faster cores. By need, on the specifications: rendering, compiling, video export: the Core i3-14100F; a quiet or compact build: the Core i3-14100F; no graphics card: the Core i5-8400. 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 i3-14100F and the Core i5-8400 use the same socket?
- No. The Core i3-14100F uses FCLGA1700 and the Core i5-8400 uses FCLGA1151, so switching means a new motherboard.
- Does the Core i3-14100F or the Core i5-8400 have integrated graphics?
- Only the Core i5-8400, which has Intel UHD Graphics 630. The Core i3-14100F needs a graphics card to show a picture.
- Which runs hotter, the Core i3-14100F or the Core i5-8400?
- The Core i5-8400 is rated at 65 W against 58 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 i3-14100F vs Intel Core i3-14100
- Intel Core i3-14100F vs AMD Ryzen 5 1600
- Intel Core i3-14100F vs AMD FX-6300
- Intel Core i3-14100F vs Intel Core i7-6850K
- Intel Core i3-14100F vs AMD Ryzen 3 3300X
- Intel Core i5-8400 vs Intel Core i7-6850K
- Intel Core i5-8400 vs Intel Core i5-8500
- Intel Core i5-8400 vs Intel Core i5-9400F
- Intel Core i5-8400 vs AMD Ryzen 5 2600
- Intel Core i5-8400 vs AMD Ryzen 5 1600
- Intel Core i5-8400 vs Intel Core i3-14100
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.