Intel takes on AMD’s Ryzen with Rocket Lake S and the Core i9-11900K

Intel debuted its next-generation 11th-gen “Rocket Lake S” desktop Core chips at CES 2021 on Monday, boasting that its flagship Core i9-11900K processor offers a 19 percent performance improvement over the prior generation, and with gaming performance that rivals AMD’s most powerful Ryzen chip.

Intel’s Core i9-11900K does take a step back: Intel’s 10th-gen Core i9-10900K offered 10 cores and 20 threads. The new i9-11900K wields just 8 cores and 16 threads instead, at turbo speeds up to 5.3 GHz (single core) and a slower 4.8GHz (all cores) than the i9-10900K offered. It’s also a 14-nanometer chip. But there are subtle, significant improvements, too: a new, wider, 8-lane DMI interface between the processor and chipset, and an increased 20 lanes of PCIe 4.0 off the CPU for GPUs and SSD storage, matching the PCIe 4.0 capabilities that AMD has offered for the last two Ryzen generations. All told, Intel’s promising up to a 19 percent IPC (instruction per clock) improvement and a 50 percent boost in integrated graphics performance, thanks to the new, integrated Xe GPU core.

Intel said that the Core i9-11900K will be available later this quarter, at an undisclosed price. Fortunately, though a new 500-series motherboard chipset will be launched alongside it, the i9-11900K will be backwards-compatible with existing 400-series motherboards. 

Intel 11th gen desktop Intel

A summary of Intel’s new Rocket Lake-S platform.

Rocket Lake…but in 14nm

Many of the features of Rocket Lake-S have been known since last October, when Intel confirmed the existence of Rocket Lake and its new CPU architecture, code-named Cypress Cove. What we didn’t know was whether the new chip would embrace Intel’s latest 10nm process or be manufactured on the relatively ancient 14nm line. Well, now we know: it’s a 14nm chip, which also explains the drop in core count, acknowledged Brandt Guttridge, Intel’s senior director of the Desktop Products Group. The Cypress Cove CPU core originally designed for 10nm was backported to the 14nm technology, he said.

“I think one of the questions many of you might have right away is, Why are you going from ten to eight cores? “ Guttridge said. “The answer to that question really goes back to…our focus was on maximizing real world performance, which is a combination of frequency and IPC [instructions per clock]. So as we looked at the microarchitecture, we ported the 10nm design for both the CPU and the graphics back to the 14nm manufacturing node. As the 10nm design has smaller transistors and the 14nm is a bit larger set, the maximum core count we could fit on Rocket Lake was eight.”

Intel core i9 11900k overview Intel

This is as much as we know of the details of the Core i9-11900K.

The other factor influencing Intel’s choice was that moving to 14nm allowed the company to take advantage of the SuperFIN transistor that Intel added to Tiger Lake. Last year, Ruth Brain, an Intel fellow specializing in technology development and interconnects, said the sum total of all of the intranode improvements made in the 14nm generations would be equaled by the one intranode performance increase from Ice Lake to Tiger Lake, via SuperFIN. 

“That trade off we got was that 19 percent IPC gain… and the 50 percent graphics improvement,” Guttridge said. “So again, the focus here was on maximizing performance for for the end users in the real world.” 

Intel didn’t specify whether Rocket Lake S formally includes DMI 4.0, though Guttridge confirmed that the interface now doubles the available lanes from four to eight. The Direct Media Interface connects the CPU and north bridge of the chipset to the PCH or south bridge. Intel’s Skylake processor, equipped with DMI 3.0, was the first to include a total of four lanes. Guttridge confirmed that Rocket Lake S provides eight lanes, doubling the bandwidth, which means that Intel has kept the link speed constant. 

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