Introduction

Intel last week debuted the 11th Gen Core "Rocket Lake" desktop processor family, and we had launch-day reviews of the Core i9-11900K flagship and the mid-range Core i5-11600K. Today, we bring you the Core i5-11400F, probably the most interesting model in the whole stack. The often-ignored SKU among Intel desktop processors for many past generations, the Core i5-xx400 is also its most popular among gamers. Popular chips of this kind included the i5-8400, i5-9400F, and i5-10400F.

These chips feature the entire Core i5 feature set at prices below $200, albeit lower clock speeds and locked overclocking. Even within these, Intel introduced a sub-segment of chips that lack integrated graphics, denoted by the "F" in the model number, which shaves a further $15–$20 off the price. The Core i5-11400F starts at just $160, which is an impressive value proposition for gamers who use graphics cards and don't need the iGPU anyway.



The new "Rocket Lake" microarchitecture brings four key changes that make it the company's first major innovation for the client desktop in several years. First, Intel is introducing the new "Cypress Cove" CPU core that promises an IPC gain of up to 19% over the previous generation. Next up is the new UHD 750 integrated graphics powered by the Intel Xe LP graphics architecture, promising up to a 50% performance uplift over the UHD 650 Gen9.5 iGPU of the previous generation. Thirdly, the much needed update to the processor's I/O, including PCI-Express 4.0 for graphics and a CPU-attached NVMe slot, and lastly, an updated memory controller that allows much higher memory overclocking potential because of the introduction of Gear 2 mode.

The Core i5-11400F comes with a permanently disabled iGPU and a locked multiplier. Intel has still enabled support for memory frequencies of up to DDR4-3200, which is now possible on even the mid-tier H570 and B560 motherboard chipsets. The i5-11400F is a 6-core/12-thread processor clocked at 2.60 GHz, with up to 4.40 GHz Turbo Boost. Each of the processor's six Cypress Cove CPU cores include 512 KB dedicated L2 cache, and the cores share 12 MB of L3 cache. Intel is rating the processor's TDP at 65 W, just like the other non-K SKUs, although it is possible to tweak these power limits—adjusting PL1 and PL2 is not considered "overclocking" by Intel, so it is not locked.

At $170, the Core i5-11400F has no real competitor from AMD. The Ryzen 5 3600 starts at around $200, and the company didn't (yet?) bother with cheaper Ryzen 5 SKUs based on "Zen 3." In this review, we take the i5-11400F for a spin to show you if it is really all you need for a mid-priced, contemporary gaming rig.

We present several data sets in our Core i5-11400F review: "Gear 1" and "Gear 2" show performance results for the processor operating at stock, with the default power limit setting active and respecting a 65 W TDP. Next up, we have two runs with the power limit setting raised to the maximum: "Max Power Limit / Gear 1" and "Max Power Limit / Gear 2." Last but not least, signifying the maximum performance you can possible achieve on this CPU, we have a "Max Power + Max BCLK" run, which operates at 102.9 MHz BCLK—the maximum allowed by the processor, at Gear 1 DDR4-3733 since the memory controller won't run higher.

Unboxing and Photography

The Core i5-11400F ships in a simple paperboard box, with a small cutout to see the processor. The box contains the processor, a cooler, a case-badge, and documentation.


With the 11th Gen Core series, Intel is including its upgraded stock fan-heatsink with all non-K SKUs, Core i5 and upward. These coolers were introduced last year with the 10th generation. The heatsink features black anodized aluminium fins, a solid copper core base plate, and an improved fan. The cooler is rated to handle thermal loads of up to 95 W, which should be just about enough for the non-K processors running at stock speeds.


The processor is based on the same Socket LGA1200 package as 10th Gen Comet Lake and will work on not just Intel 500-series chipset motherboards, but also older 400-series ones, with a BIOS update.


Intel's Socket LGA1200 uses the same mounting-hole layout as the older LGA115x configuration, giving you a huge choice in coolers. Just be sure it can handle a TDP of at least 65 W.

The Rocket Lake Microarchitecture

The new Rocket Lake microarchitecture forms the bedrock of Intel's 11th Gen Core desktop processor family. The architecture aims to introduce some of Intel's latest CPU and iGPU architectures to the desktop platform. It also brings Deep Learning Boost AI acceleration to this form factor, and AVX-512. With Rocket Lake, Intel aims to introduce their first double-digit, single-threaded CPU performance gains in five years, and a massive iGPU performance gain over the previous generation.


The Rocket Lake-S die is built on what is hopefully the final refinement of Intel's 14 nm silicon fabrication process. Why Intel didn't go with 10 nm SuperFin is anyone's guess. The company still seems to be transitioning between 14 nm and 10 nm-class nodes and is currently prioritizing mobile and enterprise processors with the new node. The price Intel pays for sticking with 14 nm does not just consist of power/thermal costs rivaling 10th Gen Comet Lake. CPU cores are also limited to a maximum of eight since the LGA1200 package has limited fiberglass substrate area.

Rocket Lake combines five key design enhancements over the previous generation. These are the new Cypress Cove CPU core, new Gen12 Xe LP integrated graphics, new Gaussian Network Accelerator (GNA) 2.0—a hardware component that enables the Deep Learning Boost (DLBoost) AI acceleration feature—AVX-512, and, lastly, the updated platform I/O that introduces PCI-Express 4.0, along with a chipset bus with double the width over the previous generation.

Cypress Cove

The new Cypress Cove CPU core is a back-port of the "Sunny Cove" core found in Ice Lake processors, to the 14 nm silicon fabrication node. Sunny Cove was originally designed for Intel's 10 nm node. Intel hasn't released core architecture documentation specific to Cypress Cove, but we can extrapolate from what precious little information Intel put out for Sunny Cove.


A CPU core has essentially three components—the front-end, a part that understands the nature of the work and allocates the right hardware resources to get it done; the Execution stage, where the actual number-crunching happens; and the Load/Store stage, which interfaces this work done/to-be-done with the memory system through the processor's cache hierarchy. Intel appears to have directed its engineering efforts toward improving the Execution and Load/Store stages.


There are numerical increases in key components that make up the Execution stage of the core: 25% more allocation width and execution ports, 33% more AGUs, and an additional Store unit in Load/Store. These changes enable support for newer instruction sets—prominently, 512-bit AVX (or AVX-512). Rocket Lake being a client microarchitecture, receives a truncated version of AVX-512 with only those instructions that are relevant to the client segment. The cache sub-system receives a much needed update with the L1 Data cache being enlarged to 48 KB (from 32 KB on Skylake) and the L2 cache being doubled in size to 512 KB. At 16 MB, the L3 cache size hasn't been changed from the previous-generation 8-core parts.

Intel Xe Graphics

The next major component is the Intel Iris Xe integrated graphics solution based on the latest Gen12 Xe LP graphics architecture. This is the same exact technology as in the Tiger Lake iGPUs, but with a slight difference. While the Tiger Lake iGPU gets 96 execution units as shown in the slide above, the Rocket Lake iGPU only has 48. This was probably done to conserve silicon real-estate on the 14 nm die. Intel attempted to make up for the deficit in EUs compared to Tiger Lake by running the iGPU at higher engine clocks and a more generous power budget than the 15-watt Tiger Lake chips launched so far. In any case, Intel claims that the iGPU on Rocket Lake performs up to 50% faster than the Gen9.5 solution found in Comet Lake. Intel updated the media engine of the iGPU to now offer hardware-acceleration of 10-bit AV1 and 12-bit HEVC video formats.

AVX-512

With this generation, Intel is introducing the new AVX-512 instruction set. This evolution of AVX and AVX2 helps accelerate SIMD workloads—similar operations on a lot of data at the same time. The whole AVX-512 instruction set is a vast set of instructions, not all of which are relevant to the client PC use case. Intel has hence truncated the instruction set, with only certain instructions available to client platforms such as Rocket Lake and Ice Lake, while enterprise/HPC products, such as Xeon Scalar processors and Xeon Phi, have different instructions. Since Cypress Cove is derived from Sunny Cove (and not "Willow Cove"), it features Foundational (F), Conflict-Detect (CD), Vector Propulsion Count (VPOPCNTDQ), Vector Length (VL), BFloat16, Vector-AES, etc., but not the Vector Intersect (VP2INTERSECT) instruction Willow Cove supports.

Gaussian Network Accelerator

Next up is GNA 2.0, the hardware component that enables DLBoost, Intel's ambitious new client processor feature that brings AI capabilities to the processor to speed up certain creativity apps that can leverage them. AI-accelerated video and image manipulation has made great strides on smartphones for the past 3+ years, and Intel sees an opportunity for it on the PC, too. DLBoost debuted in 2019 with the 10th Gen Ice Lake mobile processors, and is coming to desktop with Rocket Lake. Intel claims that it accelerates deep-learning neural net building/training by up to six times compared to native x86 machine code, which can help offload the CPU cores.