4 Cores for Ultrabooks: Core i7-8550U Overview

This was a big year for mobile Intel chips with low power consumption. For generations, we've been accepting performance improvements of less than 10% year over year, with Intel focusing on better efficiency and longer battery life. With AMD on its heels and launching its own ultra-portable processors in the near future, Intel has decided that the time for incremental improvements is over.

This is the first time that Intel's mobile chips with low power consumption have switched from a dual-core to a quad-core design. This was achieved while maintaining the same 15-watt TDP as previous U-series chips with low power consumption, which essentially allows for a big leap in performance without sacrificing battery life.

Before we look at the specific changes to the new Intel processors, let's take a quick look at the basics, especially the confusing line of Intel products for 2017.

These new mobile quad-core processors belong to the 8th generation from Intel, which consists of products from three different architectures: Coffee Lake, Cannon Lake and Kaby Lake Refresh. This is in stark contrast to the 7th generation products that all used the Kaby Lake architectures.

There are a number of reasons why Intel chose a three-architecture split for its 8th generation CPUs, but what really matters is the problems of Intel's process nodes, especially when transitioning to 10 nm. It is confusing for enthusiasts who like to immerse themselves in the architecture of Intel products, although most consumers only need to see the 8th generation branding to know that they are getting the latest CPUs in their respective categories.

Currently, the three architectures that make up the 8th generation of Intel are as follows:

  • Coffee Lake. These are 8th generation Intel CPUs for desktops and potentially future high performance laptops based on a second refinement of Intel's 14nm process (known as 14nm ++).
  • Cannon Lake. These 8th generation processors are scheduled for release in 2018 and consist of a 10nm tool shrink of the Coffee Lake architecture. It is not clear which parts will be included in the Cannon Lake line, although it is believed that they are mobile parts with low power consumption.
  • Kaby Lake Refresh. These are 8th generation Intel CPUs for laptops with low power consumption, which were built with the same process node of over 14 nm and largely the same architecture as Kaby Lake.

If you are interested in Coffee Lake chips for the desktop, you can read our review here. At the moment, however, we are discussing Kaby Lake Refresh or Kaby Lake-R for ultra-portable laptops.

As mentioned earlier, the main improvement this year to Intel's 15W parts of the U-series is the jump from two core processors with four threads with Kaby Lake to four core processors with eight threads with Kaby Lake Refresh. Doubling cores and threads is the only major change here, as Kaby Lake-R processors use the same microarchitecture (except for minor changes) and the same manufacturing node of over 14 nm + as last year's 7th generation mobile parts.

The low-power mobile chips from Intel have finally switched from a dual-core to a quad-core design for the first time

The compromise for more cores and threads in the same 15 W TDP is the fundamental frequency, which is generally lower. On the other hand, the turbo frequencies are higher, even the four-core turbo speeds, and the L3 cache can be practically increased: 8 MB for Core i7 parts and 6 MB for Core i5 parts. All Kaby Lake-R parts support LPDDR3 and DDR4 memory, with DDR4 support increasing from DDR4-2133 to DDR4-2400.

Spec Core i7-8550U Core i7-7500U Core i7-6500U Core i7-5500U
Cores / threads 4/8 2/4
Basic clock 1.8 GHz 2.7 GHz 2.5 GHz 2.4 GHz
1C Turbo Clock 4.0 GHz 3.5 GHz 3.1 GHz 3.0 GHz
2CTurbo clock 4.0 GHz 3.5 GHz 3.0 GHz 2.9 GHz
4C turbo clock 3.7 GHz N / A
GPU UHD 620 HD 620 HD 520 HD 5500
Max. GPU clock 1150 MHz 1050 MHz 1000 MHz
L3 cache 8 MB 4 MB
TDP 15W
Unit price $ 409 $ 393

In the graphics, the four Kaby Lake-R processors in this first version of the 8th generation use the Intel UHD 620 CPU, which is identical to the previously used HD 620. In other words, we still see 24 execution units with clock speeds of 1100 and 1150 MHz for Core i7 and i5 CPUs.

All in all, the Core ix-8x50U line is a direct upgrade of last year's Core ix-7x00U series. We have to wait a little longer for Intel to release the usual array of 15W and 28W CPUs of the U series with more powerful iris graphics and parts of the Y series with extremely low power consumption.

Of particular interest for this test is the Core i7-8550U, which is the direct successor to last year's Core i7-7500U. The i7-8550U is the second best Kaby Lake-R processor, with the flagship (for now) i7-8650U taking over the performance crown with slightly higher clocks.

As with all Kaby Lake-R processors, the main prize here is the jump from a 2C / 4T design to a 4C / 8T. The base clock speeds have been reduced from 2.7 to 1.8 GHz, so that two additional cores can be added to the same 15 W TDP. However, the boost frequencies have increased from 3.5 to 4.0 GHz for single and dual-core use and 3.7 GHz for all-core use, provided there is enough power and thermal headroom. The L3 cache is also 4 MB to 8 MB high.

On the GPU side, the GPU of the i7-8550U under the new name UHD 620 is almost the same as before, but up to 1150 MHz, which corresponds to a clock speed of 100 MHz, is clocked via the same 24 execution units.

It is interesting to note that prices have risen slightly over the previous year, although you cannot get off the shelf with a U-series chip. The i7-8550U now costs $ 409, up $ 16 from $ 393. This shouldn't have a significant impact on laptop pricing, but it's no real surprise that a larger CPU with more cores costs a little more.

This performance review of the Core i7-8550U was done on a Dell Inspiron 13 7000 2-in-1 that offers 1080p display with 16 GB DDR4-2400 RAM, powerful 512 GB M.2 SSD and a decent base platform for testing. The results on the next few pages are designed to give you a good idea of ​​how the i7-8550U works on a variety of devices, not just the laptop we've tested with.

In the last 12 months of laptop testing we've done with Kaby Lake, laptops with the same CPU can vary in performance benchmarks by up to five percent …

However, it is important to note that the exact performance data will vary slightly from device to device, as different laptops use different thermal solutions and have different performance goals. In the last 12 months of laptop testing we've done with Kaby Lake, laptops with the same CPU in the performance benchmarks can vary by up to five percent. So keep that in mind when we look at the performance of the Core i7-8550U.

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