Intel's Core i5-8400 marks the company's most affordable entry point into the new six-core goodness introduced with Coffee Lake. Compared to its bigger siblings, the processor lacks HyperThreading and an unlocked multiplier, but this is reflected in its price point, which at $190 essentially replaces the Core i5-7400, which only has four cores and four threads.

When averaged over our CPU test suite, which focuses on both single-threaded and multi-threaded workloads, the Core i5-8400 is more than 25% faster than the Core i5-7400 and also beats the 7600K by 15%. Against AMD's offerings, it wins the Ryzen 1600 fight with +5% but loses against the 1600X by a few percent. This puts it in a tight sandwich between AMD's offerings, which, depending on the work load, are faster (multi-threaded load) or slower (single-threaded). This means that it comes down to knowing what applications you use to make an informed buying decision.

For gaming, things are different. Here, the i5-8400 breezes past all AMD Ryzens thanks to its high per-thread performance and the boost clock of 4.0 GHz. I find it surprising that there is very little difference between the i5-8400, i5-8600K, and i7-8700K in gaming, even at the highly CPU-limited scenario of 720p. This suggests that today's games see limited gains from more than four cores. It is good news for gamers on a budget because a Core i5-8400 will be completely sufficient to not bottleneck even the fastest graphics cards.

Overclocking on the 8400 is limited due to the locked multiplier. It is still doable by changing the multiplier somewhat through adjustments to the CPU's Turbo settings, making the CPU boost to its highest single-core boost state even when multiple cores are in use. Unfortunately, that didn't work right at the time of testing. We could only achieve a x38 multiplier and not the x40 the boost can use out of the box. We combined the x38 multiplier with a 103 MHz BCLK for some extra performance, but the results are a bit disappointing. Averaged, the gains are in the single-digit percentages, which kinda makes them a waste of time in my opinion. The underlying reason here is that with our manual overclock, we are missing out on the last 200 MHz the boost will provide on its own when running untouched. Maybe this is a bug and motherboard vendors can address the issue with a new BIOS. On the other hand, it means that the Core i5-8400 out of the box will work at near its optimum, and you don't have to learn any overclocking concepts or fiddle with the BIOS if you are uncomfortable with doing so.

With a price of $190, the Core i5-8400 is the lowest-priced six-core you can buy from Intel, making it a decent choice for an affordable future-proof CPU that can drive multi-threaded workloads easily. For gamers, it's also an interesting option because at its price point - which is half that of the Core i7-8700K - you can get a six-core CPU that will run your games nearly as fast as the 8700K, with $200 saved to buy a GTX 1080 Ti instead of the GTX 1080 you would have had the money for instead.

Unfortunately, only Z370 motherboards are available at this time, which feature a lot of overclocking doodads, none of which are useful for the i5-8400. The ideal pairing in my opinion would be an affordable B360 motherboard, which I'd expect to be around $60 for another 50 bucks saved compared to a Z370 board. Of course, this will be rectified over time, as B360 boards will come out at some point in the future. For now, it opens up a lot of ground for AMD Ryzen offerings, which can be more cost-effective in terms of platform cost, with better multi-threaded performance and unlocked multipliers, though they do fall behind in single-threaded workloads and gaming.