Intel Core i5-11400F Review - The Best Rocket Lake 184

Intel Core i5-11400F Review - The Best Rocket Lake

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Value and Conclusion

  • The i5-11400F is priced at around $170.
  • Outstanding price/performance with power limit unlocked
  • Highly affordable 6c/12t option
  • Huge gains in low-threaded applications
  • Very competitively priced
  • Gaming performance "good enough"
  • PCI-Express 4.0
  • Compatible with existing Z490 motherboards
  • CPU cooler included
  • Support for AVX-512 and DLBoost
  • Worse energy efficiency than previous generation
  • High power consumption when unlocked
  • Lots of heat once power limit is unlocked
  • Multiplier locked
  • BCLK overclocking intentionally limited
  • Lacks Boost 3.0, Thermal Velocity Boost, and Adaptive Boost
  • Only minimal software support for AVX-512 and DLBoost
  • Gear 1 memory mode unable to run modern memory speeds
  • Many BIOS bugs
  • Only one PCIe 4.0 M.2 slot, other M.2 slots are PCIe 3.0
  • No integrated graphics
With their 11th generation processors, Intel is finally introducing a new architecture to replace the Skylake arch that has been dragged along since forever. At the same time, they're adding support for PCI-Express 4.0 and new instructions like DLBoost for Deep Learning and AVX-512 for SIMD calculations. At just $170, the Core i5-11400F is the company's most affordable Rocket Lake offering. The lower end of the spectrum, like Core i3 and Pentium, will be covered by Comet Lake refresh CPUs.

With our Rocket Lake reviews, we're introducing our new CPU Test Suite comprised of 38 (!) benchmarks that cover the whole spectrum of workloads, from consumer to scientific, content creation, and enterprise. The applications tested are a healthy mix of single-threaded, lightly-threaded, and fully multi-threaded workloads—just like you would encounter in real life. Averaged over all these tests, the six-core Core i5-11400F almost matches last generation's Core i5-10600K; it's also 7% faster than last generation's Core i5-10400F. On the AMD side, you have Ryzen 5 3600 and 3600X, which pretty much match the i5-11400F, and the Ryzen 5 5600X is 25% faster, at much higher cost, of course.

Performance results are a bit complicated though with the 11400F. Rocket Lake introduces a new memory controller, which has the ability to run in two modes: Gear 1 has the memory controller clock equal memory frequency and Gear 2 has the memory controller clock equal half the memory frequency. The consensus so far has been to always run Gear 1 unless you can achieve memory clocks well above DDR4-4500. That's why I did two runs at stock with Gear 1 and Gear 2, to get a feel for how much faster Gear 1 is than Gear 2. Turns out on the Core i5-11400F, Gear 1 is not faster than Gear 2. Look through the results, the difference is big enough not to be some random effect. At first, I thought this is an issue with my test setup, configuration, apps or something else. After trying various things to find the root cause, I realized that the CPU's power limit is the reason for the surprising performance difference. All modern Intel CPUs have Turbo Boost 2.0, which lets the CPU exceed its power limit for a few seconds while there is still power budget left—the goal is to average 65 W, not stay below 65 W at all times. With the memory controller working extra hard in Gear 1, at twice the operating frequency of Gear 2, it consumes A LOT more power: I measured between 5–10 W more depending on the workload—this is just to operate the memory controller at Gear 1. Everything else, memory chips, CPU IA core frequency, and voltages are identical. Obviously, these 10 W are part of the processor's power consumption and count towards its limits. On a processor with 65 W TDP, this is a significant cost—the CPU's cores can no longer boost as high, and the boost budget is exhausted sooner.

To test this theory, I ran another round of benchmarks, this time with the power limit raised to the maximum. Now the added power consumption from Gear 1 should no longer affect the processor's boosting abilities, and we should see Gear 1 faster than Gear 2. I included the whole dataset for you in the charts, which makes them a bit busier, but I found this discovery interesting enough to provide that much detail. Bottom line—if you plan on running a 65 W Rocket Lake CPU, do not bother with Gear 1 and run Gear 2 instead, which also lets you save some money on the memory modules. If you want to run Gear 1, you must absolutely raise the power limit or you will lose performance compared to Gear 2. The difference is 1.3% on average, with much bigger swings depending on the application. When running games, Gear 1 at the 65 W power limit can still come out on top because most games don't put enough load on the CPU to hit the 65 W TDP limit, or the workload is short enough to stay within the Turbo Boost 2.0 time window. So I guess for gaming, you could still do with 65 W in Gear 1.

Overall gaming performance is very decent with the Core i5-11400F; it beats all Ryzen 3000 processor and almost matches the Core i5-11600K. AMD's Zen 3 Ryzens are a bit faster, but differences are small,and probably not worth it considering AMD's higher cost. AMD's key problem here is the lack of a Ryzen 5 5600 non-X or quad-core Zen 3 processors. I'm sure with their single-threaded performance and 7 nm efficiency, smaller Zen 3 Ryzens could definitely become top choices for gamers.

What could bring big wins for Intel is the newfound love for AVX512 and DLBoost—extensions that have been available for years, but never made it to the desktop. At this time, software support for either of those instruction sets is extremely limited, and they are not useful. I am convinced that they can offer tangible benefits once adoption rates go up, though. Remember AVX—everybody said it's a useless technology that's not needed as we already have SSE; today, a lot of apps and games use AVX, also owing to excellent compiler support. Using these new instructions is often as simple as checking a box that tells the compiler it may optimize with AVX instructions—that's it. The hard work will be done by the compiler; you don't have to mess with hand-coded assembly instructions. Today, all this doesn't matter as consumers won't need AVX-512 for a couple of years at least. That said, Rocket Lake can be a cost-effective option for researchers and industry professionals who want to use these new instructions to speed up their calculations, but don't want to pay up for the expensive Xeons.

Just like their other recent desktop processors, Rocket Lake is fabricated on Intel's 14 nanometer process. The company does have a working 10 nm process, which is in production for Ice Lake, and everybody is wondering why they didn't use it for Rocket Lake. Silicon manufacturing has extremely long lead times, so I suspect they decided to continue using 14 nm well before AMD's Zen 3 came out to make sure their older fabs continue to see full use. The excellent yields on the mature 14 nm process certainly played a role in this business decision, too. The drawback of this aging technology is that power consumption is much higher than what AMD offers.

Energy efficiency has definitely suffered with Rocket Lake, even compared to Comet Lake, which wasn't impressive either. Looking at our power consumption results, we see the effects of Gear 1 vs. Gear 2, too, especially when the CPU is set to its default 65 W TDP. Even at 65 W, there's a noticeable loss in energy efficiency vs. last generation's Core i5-10400F—and that will cost you some of that awesome Cypress Cove performance improvement because the 11400F will run into its power limit sooner. Still, given decent cooling, the i5-11400F has a lot of potential, for which you should absolutely unlock its power limit.

While the Core i5-11400F does not support multiplier-based overclocking—it lacks the "K" suffix—you can still adjust the power limit freely on even the cheapest motherboards. If the BIOS does not have power limit options, ThrottleStop will let you change them from within Windows in real time. This could also be an approach handling the increased power consumption; just switch the power limit without rebooting when you need extra CPU horsepower and run at 65 W for light loads, like browsing and Office.

Multiplier-based overclocking really isn't worth it these days, especially when you take into account all the various boosting mechanisms that help eke out the last bits of performance, even at stock. BCLK-based overclocking is an alternative, but Intel has made sure to lock away the good stuff here too. The highest possible BCLK on the 11400F is 102.9 MHz—a little frequency counter inside the chip will detect 103 MHz and higher and stops the CPU for no reason other than limiting OC potential. Intel really needs to stop this segmentation BS and just give their customers more freedom, maybe that will help win back some loyalty.

While the Core i9-11900K has received Intel's full arsenal of boosting algorithms to increase the processor's clock frequencies, the Core i5-11400F only gets Turbo Boost 2.0. Don't get me wrong, even just that works really well as we reached 4.40 GHz with few CPU cores loaded, and held those quite nicely. Only with eight or more threads active did the CPU frequency drop below 4.00 GHz. Far above the 2.60 GHz base clock that seems to be more of a guaranteed minimum, possibly also for legal reasons, than a frequency you'll ever encounter in real life. I still wish Intel would have included their more advanced boost technologies on lesser SKUs.

Rocket Lake finally brings with it PCI-Express 4.0 support, which is an essential capability gamers demand these days even though it doesn't make that much of a difference, neither for graphics nor storage. With the much more modern platform, AMD is obviously capitalizing on Intel's shortcomings, even if it's just for marketing. While many pieces of the Rocket Lake puzzle are now running at PCI-Express 4.0, the chipset still puts out Gen 3 lanes, which means you're limited to one PCIe Gen 4 M.2 NVMe SSD; the other slots support Gen 3 only. This is certainly not a dealbreaker, especially for a value-oriented chip like the Core i5-11400F, but it's still worth mentioning.

What really displeases me is how tacked-together and unfinished the whole Rocket Lake platform feels. The BIOSes have numerous bugs that are completely obvious to anyone using them for more than 10 minutes. Maybe this is not Intel's fault, but since AMD introduced AGESA, a common-base software stack, things have gotten much better for the red team. POST times have always been good with Intel, but I'm now sometimes sitting at A2 (VGA) for 20 seconds with an occasional double boot when changing a BIOS setting, which we criticized AMD for in the past. This whole experience reminds me of the first generation of Ryzen.

Priced at $170, the Core i5-11400F is extremely affordable. I'd even go so far to say it's the best entry-level CPU on the market today. While you can find last generation's Core i5-10400F a little bit cheaper, application performance and resale value have me opting for the i5-11400F even though gaming performance is similar. I would definitely not buy Zen 2 over the Core i5-11400F, and AMD has failed to present any highly affordable Zen 3 option so far—I'm sure they will happily sell you the Ryzen 5 5600X instead. With an MSRP of $300, but out of stock most of the time, scalpers will take another $100 from you. Given this huge price difference, I can imagine a lot of people will be willing to overlook the Rocket Lake energy inefficiencies and platform complexities. A Ryzen 5 5600 does exist, but it is OEM only. Maybe the Core i5-11400F will help AMD remember "we love gamers," and bring the Ryzen 5 5600 to the DIY market, too. The Core i5-11400F definitely has enough gaming horsepower to feed any graphics card—the RTX 3080 ran great in our test system. Especially at higher resolutions are the differences between CPU choices small because games are more and more GPU limited. Given today's insane graphics card prices, every dollar you save on the processor will open up new GPU options for you.
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