Quick Verdict
A legendary value CPU that forced the market to adopt 6 cores as the standard. Excellent for budget gaming, though lacking Hyper-Threading.
Overview
Launch
Oct 5th, 2017
Status
End-of-lifeGeneration
Core i5 (Coffee Lake)
Market
Desktop
The Intel Core i5-8400 is a landmark mainstream desktop processor that fundamentally shifted the budget CPU market by bringing six physical cores to the i5 tier for the first time.
The Core i5-8400 delivers 6 physical cores operating up to 4.0 GHz, paired with UHD Graphics 630. It became the definitive choice for budget builders, offering enough single-core speed for modern games and daily tasks without breaking the bank.
Specifications
Performance
Handles office tasks and moderate programming workloads efficiently.
Good for basic VMs, but 6 threads limit heavy parallel virtualization.
Capable of smooth 1080p gaming when paired with a mid-range discrete GPU.
Balanced performance within a standard 65W power envelope.
- •Excellent for budget gaming builds
- •Handles eSports titles flawlessly
- •May bottleneck high-end modern GPUs at 1080p
- •No AI-specific hardware
- •CPU inference is slow due to lack of threads
Architecture
14 nm
Process Node
Coffee Lake
Codename
6C / 6T
Core Config
9 MB
L3 Cache
65 W
TDP
Architecture Overview
The Core i5-8400 leverages the Coffee Lake microarchitecture, manufactured on Intel's mature 14nm process node. At its core, it utilizes a 6-core layout arranged around a ring bus topology, ensuring low-latency communication between the processing cores, the 9MB L3 SmartCache, and the system agent. Unlike higher-tier i7 models of the same generation, the i5-8400 omits Hyper-Threading, meaning it processes one thread per core, which slightly limits its parallel processing efficiency compared to SMT-enabled competitors. The integrated Intel UHD Graphics 630 consists of 24 Execution Units and shares the system's dual-channel DDR4-2666 memory. For expansion, the CPU provides 16 PCIe 3.0 lanes directly to the processor, perfectly adequate for a single discrete graphics card and an NVMe SSD. Intel also retained crucial architectural features like AVX2 for vector math, AES-NI for hardware encryption, and VT-x/VT-d for virtualization. This architecture prioritized raw core count and predictable clock speeds over complex threading.
CPU Design
6 cores, 6 threads (no Hyper-Threading).
Memory Subsystem
Dual-channel DDR4-2666.
PCIe & I/O
16 PCIe 3.0 lanes.
Overclocking
Locked multiplier.
- Two additional physical cores
- Improved multi-threaded performance
- Better minimum frame rates in gaming
Key Highlights
- Disruptive price-to-performance ratio
- 6 physical cores for modern gaming
- Includes integrated UHD Graphics 630
- Standard 65W TDP is easy to cool
- Wide compatibility with 300-series motherboards
- No Hyper-Threading (only 6 threads)
- Locked multiplier prevents overclocking
- End-of-life platform (LGA 1151)
- Officially limited to DDR4-2666
- Not supported by Windows 11 officially
History
Launched on October 5th, 2017, the Core i5-8400 arrived at a highly competitive time in the CPU market. AMD's Ryzen 5 1600 was offering 6 cores and 12 threads at a similar price point, putting immense pressure on Intel's traditional i5 lineup. In a rapid response, Intel released the Coffee Lake generation, making 6 cores the new standard for mainstream users.
The i5-8400 became the de facto choice for countless pre-built office PCs and budget gaming rigs, largely due to its predictable performance, robust single-core speeds, and widespread OEM adoption. It represented a transitional phase for Intel, as the company maximized the potential of its 14nm node while simultaneously preparing for future lithography advancements. While enthusiasts debated its lack of Hyper-Threading, the broader consumer market embraced the i5-8400 for its reliability and value, making it one of the most ubiquitous and impactful processors of its era.
Improvements over Previous Generation
- Two additional physical cores
- Improved multi-threaded performance
- Better minimum frame rates in gaming
Alternatives & Competitors
Should You Buy It?
Recommended for the right buyer
Upgrading an older LGA 1151 system on a budget, or building an office/HTPC machine.
Avoid if…
- Building a new PC from scratch (newer platforms offer better value)
- Doing heavy 3D rendering or video editing
- Requiring high-refresh-rate gaming with top-tier GPUs
Use Cases
Interesting Facts
The i5-8400 was the first mainstream i5 processor to feature 6 physical cores.
It launched at just $182, forcing AMD to adjust Ryzen pricing.
Includes Intel UHD Graphics 630, allowing it to function without a dedicated GPU.
Uses the FC-LGA1151 package and part number SLAPL.
Features a die size of 154 mm².
Officially supports DDR4-2666 memory in dual-channel mode.
The 8th Gen lineup physically changed the LGA 1151 socket pinout to prevent use on older 100/200 series boards.
Features 16 PCIe 3.0 lanes for direct GPU and NVMe connectivity.
Has a base clock of 2.8 GHz and a max turbo of 4.0 GHz.
Can run Windows 11 despite lacking official support.
People Also Ask
Is the Intel Core i5-8400 good for gaming?
Yes, it is still capable for 1080p budget gaming when paired with a mid-range GPU.
Does the i5-8400 have Hyper-Threading?
No, it has 6 physical cores but only 6 threads, meaning no Hyper-Threading.
Can you overclock the i5-8400?
No, the multiplier is locked. Only BCLK overclocking is possible on certain motherboards, which is not recommended.
What is the max turbo frequency of the i5-8400?
The maximum turbo frequency is 4.0 GHz.
Does the i5-8400 have integrated graphics?
Yes, it includes the Intel UHD Graphics 630.
What socket does the i5-8400 use?
It uses the Intel Socket 1151 (LGA 1151).
What RAM speed does the i5-8400 support?
It officially supports DDR4-2666 memory in dual-channel mode.
Does the i5-8400 support Windows 11?
Officially no, but it can run Windows 11 via registry workarounds.
What was the launch price of the i5-8400?
It launched at $182.
Can the i5-8400 work on a 200-series motherboard?
Not officially. Intel changed the electrical pinout, though hardware hackers have modified boards to work.
Frequently Asked Questions
Does the i5-8400 come with a cooler?
Yes, retail boxed versions include a standard Intel stock cooler.
Can the i5-8400 run 4K video?
Yes, it can decode and play 4K video smoothly using the integrated UHD Graphics 630.
What motherboards support the i5-8400?
It is compatible with Intel 300-series chipset motherboards (Z390, B360, H310, etc.).
Does the i5-8400 support PCIe 4.0?
No, it only supports PCIe 3.0.
What is the cache size of the i5-8400?
It has a 9 MB L3 SmartCache.
Is the i5-8400 good for streaming?
It can handle basic streaming, but the lack of threads may cause stuttering in CPU-heavy games.
What is the base clock of the i5-8400?
The base clock is 2.8 GHz.
Can the i5-8400 run AutoCAD?
Yes, it is perfectly capable of running 2D AutoCAD and moderate 3D modeling.
Does the i5-8400 support ECC memory?
No, the i5-8400 does not support Error-Correcting Code (ECC) memory.
What is the part number for the i5-8400?
The part number is SLAPL.