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Intel Core i7-5820K
The cheapest entry into Intel's X99 platform: six Haswell-E cores, twelve threads and quad-channel DDR4 for roughly the price of a mainstream quad-core, with the catch that it exposes only 28 PCIe lanes instead of 40. Realistically a used-only buy today, and only worth it if an X99 board and DDR4 kit are already on hand.
Pros
- 6C/12T with a fully unlocked multiplier; 4.3-4.5 GHz all-core was a routine overclock
- Quad-channel DDR4 gives it far more memory bandwidth than any contemporary mainstream chip
- 15 MB L3, identical to the much pricier i7-5930K
- 28 PCIe 3.0 lanes still allow a GPU at x16 plus an NVMe drive and a spare card
- X99 boards bring heavy VRMs, eight DIMM slots and lots of SATA/USB for very little used money
Cons
- 28 lanes rather than 40 — x16/x16 multi-GPU is off the table and some X99 boards disable slots accordingly
- 140 W TDP with no cooler included; needs a large tower cooler or an AIO
- 3.3 GHz base / 3.6 GHz turbo makes stock single-thread performance weak next to anything modern
- Haswell-era Spectre/Meltdown/MDS mitigations cost real performance and platform microcode support has ended
Below average
Computed from specs & benchmarks via our public methodology.
Full specifications
Everything we track for the Intel Core i7-5820K
General
- Announced
- 2014
- Socket
- LGA2011-v3
- Process
- 22 nm
- Base TDP
- 140 W
- Unlocked multiplier
- Yes
- Cooler included
- No
Cores & Clocks
- Cores
- 6
- Performance cores
- 6
- Efficiency cores
- 0
- Threads
- 12
- Base clock
- 3.3 GHz
- Boost clock
- 3.6 GHz
- L2 cache
- 1.5 MB
- L3 cache
- 15 MB
Memory
- Memory support
- DDR4-2133
- Max memory
- 64 GB
- Memory channels
- 4
Platform
- PCIe version
- 3
- CPU PCIe lanes
- 28
Benchmarks
- Cinebench R23 (single)
- 890Bottom 5%
- Cinebench R23 (multi)
- 6,400Bottom 14%
- PassMark
- 9,831Bottom 16%
- PassMark (single thread)
- 1,992Bottom 3%
Quick answers
Is the Intel Core i7-5820K good in 2026?
The Intel Core i7-5820K earns an Inno Score of 28.4/100 (“Below average”) based on its specs and benchmark results. The cheapest entry into Intel's X99 platform: six Haswell-E cores, twelve threads and quad-channel DDR4 for roughly the price of a mainstream quad-core, with the catch that it exposes only 28 PCIe lanes instead of 40. Realistically a used-only buy today, and only worth it if an X99 board and DDR4 kit are already on hand.
What are the key specs of the Intel Core i7-5820K?
Cores: 6 · Threads: 12 · Boost clock: 3.6 GHz · Socket: LGA2011-v3
What are the closest alternatives to the Intel Core i7-5820K?
Its closest rivals on InnoReviews are Intel Core i5-9400, AMD Ryzen 3 4300G, Intel Core i5-8500 — open the comparison pages for a spec-by-spec breakdown.
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