A Moderate Refresh

Intel announced its Core i5-9400 processors in January, but the chips only recently become available in significant quantities. The company also rolled out the rest of its Coffee Lake refresh models , six months after its initial salvo , a delay likely attributable to its ongoing 14nm production shortage.

As Intel struggles to satisfy demand for its chips, AMD has launched its Ryzen 3000-series processors. The updated Ryzen line-up employs a smaller 7nm process that should confer power and price benefits. It'll also wield the new Zen 2 microarchitecture, which is expected to boost performance while Intel remains mired in a derivative of the seven-year-old Skylake design. These chips have now taken our Best CPUs list by storm , so be sure to head there for a list of the latest leading processors.

Intel's lingering lack of 14nm capacity reverberates through every facet of the industry. To boost supply, the chip-maker decided to start selling CPUs that it would have otherwise deemed defective due to nonfunctional graphics units. As a result, we now have the F-series, which includes disabled graphics hardware, but is otherwise identical to the fully-featured Core processors we're more accustomed to.

That means the Core i5-9400F is nearly identical to the Core i5-9400. Both CPUs serve to replace the impressive Core i5-8400 , which was one of the most popular Coffee Lake models. Armed with 6C/6T and a slightly higher clock rate, the 9400s yield an incremental step forward over their predecessor.

Moreover, we're finally seeing the F-series' lower price kick in. The Core i5-9400F's ~$20 discount could be compelling for mid-range gamers who don't need integrated graphics.

Core i5-9400F and Core i5-9400

From an architectural standpoint, the Core i5-9400 and -9400F are essentially the same processor as the Core i5-8400, right down to their 14nm++ process, six physical cores, support for dual-channel DDR4-2666, and 65W TDP. The CPUs also drop into an LGA 1551 interface, and they are supported by existing 300-series motherboards with up-to-date BIOSes. They're multipler-locked, unfortunately, so they include Intel's flimsy stock cooling solution.

Again, the Core i5-9400F lacks integrated graphics, which isn't an issue for gamers who already use add-in GPUs. However, we find it interesting that Intel maintains the same $182 recommended price as its standard Core i5-9400.

Relative to the Core 5-8400, Intel boosts the -9400/-9400F's base frequency and Turbo Boost clock rate by 100 MHz, which should yield slight performance benefits. The Core i5-9400 models also include new baked-in silicon mitigations for the Meltdown vulnerability , along with a combination of hardware- and software-based mitigations for the Spectre and L1TF vulnerabilities. The overhead of software-based patches applied to older processors can reach as high as 10% in certain workloads. That impact is greatly reduced on newer processors. Compared to the Core i5-8400, we didn't measure any significant speed-ups beyond what we expected. However, optimized mitigations could help deliver more of a performance uplift to enthusiasts migrating from much older platforms.

With the launch of its Coffee Lake refresh, Intel finally switched to a solder-based thermal interface material (sTIM), improving heat transfer between its die and heat spreader. Interestingly, though, some Core i5-9400 models initially came with standard polymer-based thermal interface material (thermal grease), while others shipped with the more efficient sTIM. Intel tells us that depended on where each CPU was manufactured, though all Core i5-9400s now come with sTIM, while the locked F-series models continue to employ pTIM.

In either case, you can determine whether your CPU includes sTIM by checking its stepping. P0- and R0-stepping processors come with sTIM, while the U0 and B0 steppings utilize pTIM. Intel plans to stick with pTIM for all locked F-series models, like our U0-stepping Core i5-9400F.

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