CPU Comparison
Intel Core i5-8400T vs Intel Core i9-9900T
A side-by-side comparison of specs, performance and value. The Intel Core i5-8400T is a low-power desktop processor belonging to the 8th generation Coffee Lake family. Released in April 2018, it is built on the 14nm process and features 6 cores and 6 threads. Unlike the standard i5-8400, the 'T' suffix denotes a reduced 35W TDP, making it ideal for small form factor (SFF) PCs and home theater setups. The base clock is set at 1.7 GHz, with a maximum turbo boost of 3.3 GHz. It includes 9 MB of Intel Smart Cache and supports dual-channel DDR4 memory up to 2666 MT/s. The integrated Intel UHD Graphics 630 handles basic display tasks. With 16 PCIe 3.0 lanes, it provides adequate expansion options. The i5-8400T is compatible with LGA 1151 sockets, though it requires 300-series chipsets for official support, offering a balance of efficiency and multi-core capability.
The Bottom Line
Overview & Launch
Specifications Compared
Performance Compared
Productivity
6 cores handle office tasks easily, though single-core is slower.
Strong multi-threaded capability for office applications and light creative work.
Gaming
Can handle light gaming, but low clocks limit high-refresh gaming.
Lower clocks limit high-refresh-rate gaming, but integrated graphics handle casual titles.
Virtualization
Good for 1-2 VMs, but lacks hyper-threading.
Sufficient for basic virtualization tasks, but not ideal for heavy VM workloads.
Efficiency
Outstanding efficiency with a 35W TDP.
Exceptional power efficiency is the primary design goal and key strength.
Specialized Performance
AI / ML
- No dedicated AI hardware.
- Low clocks make inference slow.
- No dedicated AI acceleration
- Only suitable for lightweight, CPU-based inference
Content Creation
Gaming
- Low base clock can cause stuttering in CPU-bound games.
- UHD 630 is only good for very light titles.
- Best paired with a low-end discrete GPU if gaming.
- Not intended for serious gaming
- Limited by low base and boost clocks
- UHD Graphics 630 suitable only for very light or older games
Industry Impact
Best CPU by Use Case
Target Audience
Strengths & Weaknesses
Pros
- Extremely low 35W TDP
- 6 cores for parallel tasks
- Runs very cool
- Good for small form factor builds
Cons
- Low base and boost clocks
- Locked multiplier
- No Hyper-Threading
- End-of-life platform
Pros
- Exceptionally low 35W TDP for quiet and cool operation
- Full 8-core/16-thread Coffee Lake performance
- Configurable down to 25W for embedded or low-power designs
- Integrated graphics for display output without a GPU
- Often available at a deep discount on the used market
Cons
- Significantly lower clock speeds than standard desktop CPUs
- Locked multiplier limits performance tuning
- On the older LGA1151 platform with no future upgrade path
- Discontinued, with limited availability and support
- Not competitive for gaming or performance-critical tasks
Competitors & Alternatives
Intel Core i5-8400T
- AMD Ryzen 5 2400GERival
Low Power Desktop
- Compare head-to-headIntel Core i5-8400Rival
Mainstream Desktop
- AMD Ryzen 5 2600ERival
Low Power Desktop
- Compare head-to-headIntel Core i5-7400TRival
Previous Gen Low Power
- AMD Ryzen 3 2200GERival
Budget Low Power
Slightly faster clocks, same TDP.
Compare head-to-head- AMD Ryzen 5 3400GEAlt
Better integrated graphics.
Much faster modern architecture.
Compare head-to-head- AMD Ryzen 5 5600GEAlt
Better efficiency and performance.
Slightly higher clocks if buying used.
Compare head-to-head
Intel Core i9-9900T
- AMD Ryzen 7 2700XRival
High-Performance Desktop
- Intel Core i7-9700TRival
Power-Optimized Desktop
- Compare head-to-headIntel Core i5-9500TRival
Power-Optimized Desktop
- AMD Ryzen 5 3400GERival
Power-Optimized Desktop APU
- Compare head-to-headIntel Core i9-9900Rival
Standard Desktop
Much higher performance for gaming and productivity, but requires better cooling and power.
Compare head-to-headFar superior performance, modern platform, and efficiency; a better new buy.
Compare head-to-head- AMD Ryzen 7 5700GAlt
Strong APU with better integrated graphics and comparable efficiency.
Excellent single-thread performance and efficiency for basic tasks on a modern platform.
Compare head-to-head- AMD Ryzen 5 5600Alt
Better overall performance and value on a more modern platform.
Our Verdict on Each
A highly efficient 6-core processor perfect for compact builds, though its low clock speeds limit performance compared to the standard 8400.
Best for: Building a quiet home server or retro gaming rig on a budget.
Read the full reviewA capable 8-core CPU that trades raw clock speed for significantly lower power consumption, ideal for specific use cases where efficiency and thermals matter more than maximum performance.
Best for: Building or upgrading a very quiet, small form factor PC where low power and heat are critical, and the CPU can be found at a significant discount.
Read the full reviewFrequently Asked Questions
Which is faster for gaming, Intel Core i5-8400T or Intel Core i9-9900T?
For gaming, the Intel Core i9-9900T leads with a gaming performance score of 70/100 among Intel Core i5-8400T and Intel Core i9-9900T.
Do Intel Core i5-8400T and Intel Core i9-9900T use the same socket?
No. They use different sockets (Intel Core i5-8400T: LGA 1151, Intel Core i9-9900T: FCLGA1151), so each needs a compatible motherboard.
Which has more cores?
The Intel Core i9-9900T has the most cores. Core counts: Intel Core i5-8400T (6 cores), Intel Core i9-9900T (8 cores).
Which is faster in multi-core benchmarks?
The Intel Core i9-9900T posts the highest multi-core benchmark score. Multi-core results: Intel Core i5-8400T (8,500), Intel Core i9-9900T (13,086). Benchmark figures are approximate and workload-dependent.