Performance comparison: which is faster?
Core i5-8400 (Intel, 2018) and Core i7-5775C (Intel, 2015) 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: i5-8400 is about 5.3% faster
The sockets differ (LGA1151 / LGA1150), so switching requires a motherboard replacement. 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 | i5-8400 | i7-5775C |
|---|---|---|
| Performance Score | 10,000 | 9,500 |
| Generation | 8th Gen | 5th Gen |
| Socket | LGA1151 | LGA1150 |
| Release Year | 2018 | 2015 |
| Type | Desktop | Desktop |
| Compatible GPU Example | Radeon RX 6650 XT | Intel Arc A580 8GB |
| If You Want To... | Recommended |
|---|---|
| Prioritize maximum speed for heavy work or a high-end GPU | i5-8400 |
| Upgrade while reusing the current motherboard | Choose the CPU matching your motherboard socket |
| Prioritize value and adequate performance | i7-5775C (the lower model is often sufficient) |
i5-8400 is about 5.3% higher by score (i5-8400: 10000 points / i7-5775C: 9500 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.
i5-8400 is 8th Gen, while i7-5775C is 5th Gen.The sockets differ (LGA1151 / LGA1150), so switching requires a motherboard replacement.
Using our CPU:GPU = 0.9:1 guideline, Radeon RX 6650 XT pairs well with i5-8400 and Intel Arc A580 8GB pairs well with i7-5775C. If either GPU is too strong or too weak, one part holds the other back.
