Performance comparison: which is faster?
Core i5-9400 (Intel, 2019) and Core i5-8400 (Intel, 2018) are compared here. Compare not only scores, but also whether the motherboard can be reused and which GPU class is balanced with each CPU.
Overall performance: i5-9400 is about 5% faster
Both use the same LGA1151 socket, so they can be installed on the same motherboard. For games, performance balance with the GPU (guideline CPU:GPU = 0.9:1) matters more than CPU speed alone.
Relative performance score (higher is faster). Actual speed varies by workload, cooling, and memory configuration.
| Item | i5-9400 | i5-8400 |
|---|---|---|
| Performance Score | 10,500 | 10,000 |
| Generation | 9th Gen | 8th Gen |
| Socket | LGA1151 | LGA1151 |
| Release Year | 2019 | 2018 |
| Type | Desktop | Desktop |
| Compatible GPU Example | GeForce RTX 5050 | Radeon RX 6650 XT |
| If You Want To... | Recommended |
|---|---|
| Prioritize maximum speed for heavy work or a high-end GPU | i5-9400 |
| Upgrade while reusing the current motherboard | Either works (same LGA1151 socket) |
| Prioritize value and adequate performance | i5-8400 (the lower model is often sufficient) |
i5-9400 is about 5% higher by score (i5-9400: 10500 points / i5-8400: 10000 points). For gaming, the GPU tier usually matters more than a few percent of CPU difference. For CPU-heavy work such as video editing and streaming, choose the faster CPU.
i5-9400 is 9th Gen, while i5-8400 is 8th Gen.Both use the same LGA1151 socket, so they can be installed on the same motherboard.
Using our CPU:GPU = 0.9:1 guideline, GeForce RTX 5050 pairs well with i5-9400 and Radeon RX 6650 XT pairs well with i5-8400. If either GPU is too strong or too weak, one part holds the other back.
