Intel Core i7-11700K Review: Blasting Off with Rocket Lake

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The march on performance with desktop platforms has unique challenges compared to other platforms. Peak single thread throughput is often considered the Holy Grail, with a fast follow up of good multi-core and all-core performance given the nature of how desktop platforms are used with background processes and multiple concurrent applications. In order to bring its best single core performance to the desktop market, Intel had to redesign its 10nm product on 14nm, which combines the high throughput of the design with the high frequency of 14nm. These redesigned Cypress Cove cores form the basis of Intel’s new 11[sup]th[/sup] Gen Desktop Processor Family, Rocket Lake. Today we are reviewing the Core i7-11700K, an eight-core processor with hyperthreading able to boost up to 5.0 GHz.

Notice

The official launch date for these processors, and full reviews, is March 30[sup]th[/sup]. We are currently under NDA with Intel for the information that has been provided by Intel, and will publish that information in due course. However, as noted in a number of press outlets, some units have already been sold at retail before that sales date. Units obtained by that method are not under NDA by definition, and we obtained the Core i7-11700K for this review at retail, and as such we are not under NDA for any information we have obtained through using this processor.
Before publishing this review, we gave Intel advance notice to respond to us having a full review ahead of the formal release. Our email seemingly generated some excitement inside (and to our surprise, outside) Intel, but we received a response from Intel stating that they had no comment to offer.

Rocket Lake We Know About

Core i9-11900K and Core i7-11700K

Back at the start of the year, during CES, Intel disclosed product information about its lead halo product on the Rocket Lake platform, the Core i9-11900K. This includes some microarchitecture details, as well as core count, frequency, memory, graphics, and features relating to IO and the chipset. With our review here today, we can add the 11700K to that data with what we can probe from the processor.

The differences between the two Rocket Lake processors, based on available information, are slim. The main difference is that the Core i9 is known to have Intel’s Thermal Velocity Boost technology, however the Core i7 does not – this means the peak frequency is only 5.0 GHz, not 5.3 GHz. The all core frequency is only 200 MHz different.

We can see that the new design is an amalgam of new technologies, by comparing Rocket Lake to Comet Lake, Ice Lake, and Tiger Lake .There are obviously some differences between the notebook and desktop parts, most noticeably that the new platform at the high-end has only eight cores, two fewer than Comet Lake.

This is because Intel found 8 cores to be the best balance of die area, power consumption, performance, and cost. Several times I’ve seen Intel spokespeople say the reason for 8 cores being ‘the most we could fit’, although that’s categorically false. More cores can be added, but overall they would run at a lower frequency for the same power, the interconnect might not scale, or the die size/yield would raise the price too much. The phrase ‘the most we could fit’, by all technical understanding, is a steaming pile. It needs additional qualifiers, or to simply say 'the best fit given die area, yield, and cost'.

Additional improvements over Comet Lake include AVX512 units, support for 20 PCIe 4.0 lanes, and faster memory. With the new chipsets, Intel has already disclosed that the Rocket Lake platform will have native USB 3.2 Gen 2x2 (20 Gbps), and with the Z590 motherboards, a double bandwidth link from CPU to the chipset, moving from DMI x4 to DMI x8, effectively a PCIe 3.0 x8 link.

Rocket Lake on 14nm: The Best of a Bad Situation

The delays around the viability of Intel’s 10nm manufacturing have been well documented. To date, the company has launched several products on its 10nm process for notebooks, such as Cannon Lake, Ice Lake, Jasper Lake, Elkhart Lake, and Tiger Lake. There have been other non-consumer products, such as Agilex FPGAs and Snow Ridge 5G SoCs, and Intel has confirmed that its 10nm server products ‘Ice Lake Xeon Scalable’, are currently in volume production for a late Q1 launch.

The one product line missing from that list is the desktop and enthusiast segments that typically use socketed processors paired with discrete graphics. Intel has always committed to launching desktop processors on its 10nm process, however we are yet to see the results of their efforts. The issues Intel is having with 10nm have never been fully elaborated on, with Intel instead opting to promote some of the improvements made, such as its new SuperFin technology, which is in Tiger Lake and the next-generation server platform beyond Ice Lake Xeon Scalable (for those keeping track, that would be Sapphire Rapids). The 10nm improvements so far has enabled Intel to launch notebook processors and server processors, both of which have lower power-per-core than a typical desktop offering.

As 10nm has not been able to meet the standards required for desktop-level performance, rather than leave a potential 3 year gap in the desktop product family, Intel has been in a holding pattern releasing slightly upgraded versions of Skylake on slightly improved variants of 14nm. The first two members of the Skylake family, Skylake and Kaby Lake were released as expected. While waiting, we saw Intel release Coffee Lake, Coffee Lake Refresh, and Comet Lake.

Each of these afforded minor updates in frequency, or core count, or power, but very little in the way of fundamental microarchitectural improvement. The goal all along was to move to 10nm with the same architecture as the mobile Ice Lake processors, but that wasn’t feasible due to manufacturing limitations limiting how well the processors scaled to desktop level power.

• Skylake, Core 6th Gen in August 2015
  
• Kaby Lake, Core 7th Gen in January 2017
  
• Coffee Lake, Core 8th Gen in October 2017
  
• Coffee Lake Refresh, Core 9th Gen in October 2018
  
• Comet Lake, Core 10th Gen in April 2020
  
• Rocket Lake, Core 11th Gen in March 2021
  

With previous generations, Intel traditionally had either upgraded the process node technology, or updated the microarchitecture – a process that Intel called Tick-Tock. Originally Intel was set to perform a normal ‘Tick’ after Kaby Lake, and have Cannon Lake with the same effective Skylake microarchitecture move to 10nm. Cannon Lake ending up only as a laptop processor with no working graphics in a small number of notebooks in China as it was a hot mess (as shown in our review). As a result, Intel refocused its 10nm for notebook processors hoping that advances would also be applicable to desktop, but the company had to release minor upgrades on desktop from Coffee Lake onwards to keep the product line going.

This meant that at some level Intel knew that it would have to combine both a new architecture and a new process node jump into one product cycle. At some point however, Intel realized that the intercept point with having a new microarchitecture and the jump for the desktop to 10nm was very blurry, and somewhat intangible, and at a time when its main competitor was starting to make noise about a new product that could reach parity in single core performance. In order to keep these important product lines going, drastic measures would have to be taken.

After many meetings with many biscuits, we presume, the decision was made that Intel would take the core microarchitecture design from 10nm Ice Lake, which couldn’t reach high enough frequencies under desktop power, and repackage that design for the more dependable 14nm node which could reach the required absolute performance numbers. This is known as a ‘backport’.
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