CPU Comparison
Core i5-6400 vs Intel Core i5-6600
A side-by-side comparison of specs, performance and value. The Intel Core i5-6400 is a 6th generation desktop processor launched in July 2015 as part of the Skylake architecture. Designed for the LGA 1151 socket, it brought the 14nm manufacturing process to the mainstream market. This quad-core processor operates at a base frequency of 2.7 GHz and boosts up to 3.3 GHz. Unlike its predecessor, the 6400 natively supports DDR4 memory alongside DDR3L, offering a transitional platform for motherboard manufacturers. It features 6MB of L3 cache and a modest 65W TDP, making it highly energy efficient for its time. The inclusion of Intel HD Graphics 530 provided competent integrated graphics for non-gaming workloads. While it lacked an unlocked multiplier, it became a favorite for budget builders and system integrators. Its reliable quad-core performance made it a staple in office PCs and budget gaming rigs when paired with a dedicated GPU, serving as a workhorse for years before multi-threading demands outpaced its capabilities.
The Bottom Line
Overview & Launch
Specifications Compared
Performance Compared
Productivity
Sufficient for basic office applications and web browsing, but struggles with heavy multitasking.
Fast single-core makes everyday tasks snappy, but multi-threaded work is slow.
Gaming
Severely bottlenecks modern GPUs. Only playable in older or very light eSports titles.
Good 1080p performance in older games, but severe stuttering in modern CPU-heavy titles.
Virtualization
Limited to very light virtualization due to 4 threads.
Inadequate for running multiple VMs due to 4 threads.
Efficiency
Efficient for its time, but superseded by modern 10nm/Intel 7 processes.
65W TDP provides a great balance of performance and power draw.
Specialized Performance
AI / ML
- No AI acceleration
- Insufficient threads for modern AI workloads
- No AI hardware acceleration
- 4 threads are insufficient for modern AI workloads
Content Creation
Gaming
- Low base clock limits frame rates
- 4 cores cause stuttering in modern games
- Acceptable only for retro gaming
- 3.9 GHz turbo provides solid single-core grunt
- Lacks the threads for modern open-world games
- Will bottleneck mid-range modern GPUs at 1080p
Industry Impact
Best CPU by Use Case
Target Audience
Strengths & Weaknesses
Pros
- Low 65W TDP for easy cooling
- Supports both DDR4 and DDR3L memory
- Solid single-core performance for its generation
- Includes HD Graphics 530 for display tasks
Cons
- Only 4 cores and 4 threads
- Low base clock of 2.7 GHz
- Locked multiplier prevents overclocking
- Not supported by Windows 11
Pros
- High 3.9 GHz single-core turbo
- Solid 3.6 GHz all-core turbo
- 65W TDP is easy to cool
- Included a decent stock cooler
Cons
- Only 4 threads without Hyper-Threading
- Locked multiplier
- End-of-life platform with no upgrade path
- Struggles in modern multi-threaded workloads
Competitors & Alternatives
Core i5-6400
- AMD FX-8350Rival
Desktop
- Compare head-to-headIntel Core i5-6500Rival
Desktop
- AMD FX-6300Rival
Desktop
- Intel Core i3-6100Rival
Desktop
- AMD Ryzen 5 1400Rival
Desktop
Vastly better performance and platform for a similar budget.
Compare head-to-head- AMD Ryzen 5 3600Alt
More cores and threads for better multi-threaded workloads.
Slight performance bump on the same socket if upgrading cheaply.
Compare head-to-headHyper-threading on the same socket for better multi-core performance.
Compare head-to-head- AMD Ryzen 5 2600Alt
Modern alternative with more threads and better upgrade path.
Intel Core i5-6600
- AMD FX-8370Rival
Mainstream Desktop
- Compare head-to-headIntel Core i5-6600KRival
Enthusiast Desktop
- Compare head-to-headIntel Core i5-4690Rival
Previous Gen
- AMD FX-6350Rival
Budget Desktop
- Compare head-to-headIntel Core i7-4790Rival
High-End Previous Gen
Modern budget king that obliterates the i5-6600 in single-core and multi-core.
Compare head-to-head- AMD Ryzen 5 5600Alt
6 cores/12 threads, much better for gaming and productivity today.
- Intel Core i5-12400FAlt
The direct modern equivalent with 12 threads and superior IPC.
- AMD Ryzen 5 3600Alt
Older generation but still vastly superior in multi-threaded tasks.
Cheap 6-core/12-thread option on the used market.
Compare head-to-head
Our Verdict on Each
The Core i5-6400 was a fantastic budget CPU in 2015, but its 4-core/4-thread design and low clock speeds make it heavily outdated for modern gaming and productivity.
Best for: Building a retro gaming PC or basic office machine from used parts
Read the full reviewThe i5-6600 was the ultimate locked gaming chip of 2015, boasting high boost clocks, though modern users will find its 4-thread design a major bottleneck.
Best for: The i5-6600 is a solid drop-in upgrade if you are currently running a Pentium or i3 on an LGA 1151 motherboard and can get this chip for dirt cheap. It offers a noticeable bump in single-core speed and cache over lower-tier Skylake chips, making your system feel much snappier for daily use and older games. It’s also a decent holdover chip if your main CPU died and you need a cheap replacement. However, buying this to build a new system is a mistake. Modern budget chips like the i3-12100F offer vastly superior single-thread and multi-thread performance, alongside modern platform features. Do not overspend on this legacy hardware; your money is better saved for a modern platform overhaul.
Read the full reviewFrequently Asked Questions
Which is better, Core i5-6400 or Intel Core i5-6600?
Based on our editorial ratings, the Intel Core i5-6600 comes out ahead with a score of 7.2/10. That said, the best choice depends on your workload — check the spec and performance breakdown above for gaming, productivity and efficiency differences.
Which is faster for gaming, Core i5-6400 or Intel Core i5-6600?
For gaming, the Intel Core i5-6600 leads with a gaming performance score of 60/100 among Core i5-6400 and Intel Core i5-6600.
Do Core i5-6400 and Intel Core i5-6600 use the same socket?
Yes — all of these CPUs use the LGA 1151 socket, so they share compatible motherboards.
Which is faster in multi-core benchmarks?
The Intel Core i5-6600 posts the highest multi-core benchmark score. Multi-core results: Intel Core i5-6600 (5,600). Benchmark figures are approximate and workload-dependent.