Intel Coffee Lake
A solid step forward for Intel, but if you were hoping for Ryzen to be blasted from the water then look away
Intel has been on the back foot in 2017. The momentum has all been with its old rival AMD, whose Ryzen CPUs have offered more raw processing power than Intel’s Kaby Lake desktop chips – at lower prices.
But the processor business moves quickly. Intel’s new eighthgeneration desktop chips – dubbed Coffee Lake – bring more cores and higher clock speeds than ever before. Can Coffee Lake topple Ryzen and win back the CPU crown for Intel?
Inside Coffee Lake
First, the bad news: if you’ve been waiting for Intel’s promised move to a 10nm manufacturing process, you’re in for a disappointment, because Coffee Lake isn’t it. Intel has promised that the first 10nm processors will trickle out “in a low volume product” before the end of 2017, but its mainstream chips will remain – for a third year running – at 14nm.
Indeed, architecturally speaking, Coffee Lake chips are almost identical to their Kaby Lake and Skylake predecessors, with both CPU and GPU using the same core logic as before. However, a few key changes to the packaging make Coffee Lake a notable step up from the last generation.
The first is the number of cores you get. Six new chips have been announced ( see the table opposite), and all of them feature more physical cores than their Kaby Lake predecessors. The new Core i7 models have been bumped up from four cores to six, with Intel’s Hyper-Threading technology allowing them to handle 12 processes at once. The new Core i5 chips also have six cores, but no Hyper-Threading, and the Core i3 models have seen their core count doubled from two to four.
To help keep all those cores fed with instructions and data, the new chips also have bigger caches than the old Kaby Lake models. Last-generation Core i3 chips had either 3MB or 4MB of L3 “smart” cache; that’s now been extended to 6MB. Core i5 models are up from 6MB to 9MB, and Core i7 chips are raised from 8MB to 12MB.
On top of this, progressive refinements to the 14nm manufacturing process allow Coffee Lake chips to run at higher clock speeds than their forebears. The top-end Core i7-8700K has a stock speed of 3.7GHz and a maximum Turbo Boost speed of 4.7GHz, up from the 4.5GHz of last year’s model. Those speeds are unlocked too, so you can push higher if you wish.
These changes come at a cost, though, in the shape of upgraded power demands. As a result, even though Coffee Lake chips use the familiar LGA 1151 socket, they won’t work in older motherboards designed for Skylake and Kaby Lake: you’ll need a board based on the new 300-series chipset.
Speed tests
“Intel’s new eighthgeneration desktop chips, dubbed Coffee Lake, bring more cores and higher clock speeds than ever”
Intel’s processors have always had the edge over AMD when it comes to single-threaded tasks. The question is whether Coffee Lake’s extra cores and speed enhancements are enough to close the gap in multithreaded workloads too. To find out just what the new chips are capable of, we first tested the top-tier Core i7-8700K, which sells for around £360. For this we used our regular desktop benchmarks, running on Windows 10 64-bit with 8GB of DDR4-2400 RAM. With the CPU at stock speeds, we saw scores of 163 for image editing, 202 for video editing and 226 for multitasking, for an overall score of 208. That’s a lot of power, and a real step up from Kaby Lake: systems based on the last-generation Core i7-7700K have tended to score around 180 overall. However, it’s not enough to unseat AMD. Systems based on the high-end Ryzen 7 1800X CPU typically attain overall scores of 270 and up. And while that’s admittedly a more expensive chip, even the Ryzen 7 1700 outpaced the Core i7, with an overall score of 240 – and that chip costs nearly £100 less. To see if the Intel chip could catch up, we then tried overclocking. A new feature in the 300-series chipset allows you to set
the maximum Turbo Boost ratio for each core individually, so if you have the time and the inclination you can experiment and run every core at the absolute fastest speed it can stably support. For simplicity, though, we set all cores to the same frequency.
Even then, we were pleasantly surprised to see our test CPU remain stable at speeds up to 5.1GHz – and that’s using a stock Intel air cooler. Sadly, thermal throttling quickly kicked in, meaning we saw almost no real improvement in performance: the overall benchmark score merely ticked up to 212. It looks like you’ll have to resort to a pricey liquid cooling system to get a significant performance uplift.
Finally, we also tested the midrange Core i5-8400. At £173, this costs around half the price of the unlocked Core i7 – and it delivers a lot more than half the power, giving us an overall benchmark score of 162. That’s good, but again it’s not a Ryzen-beater. The closest AMD rival we’ve tested is the £218 Ryzen 5 1600X ( see issue 275,
p75), which achieved a much higher overall benchmark of 210.
Upgraded graphics
While the graphics processor in the new Coffee Lake chips is fundamentally the same as the one in last year’s Kaby Lake chips, it’s been updated with native support for HDR 4K video – hence the name upgrade from “HD Graphics” to “UHD Graphics”. The clock speeds have been nudged upwards as well, making it the most powerful integrated GPU Intel has yet produced.
That doesn’t mean you can use it to play high-end 3D games, however – at least, not without dialling the detail settings right down. To get Metro Last Light: Redux up to a playable frame rate, we had to reduce the screen resolution to 720p and disable motion blur and anti-aliasing. Even then it chugged along at 36fps.
Still, let’s not forget that AMD’s Ryzen CPUs don’t include built-in graphics at all. So the GPU is definitely a point in Intel’s favour if you don’t already have a graphics card, or if you’re looking to build a simple, low-power system for desktop role.
The verdict
Intel’s new Coffee Lake chips are certainly more powerful than their predecessors – the extra cores and higher clock speeds see to that. However, AMD’s Ryzen chips still undeniably deliver more bang per buck – and even if you’re already using a recent Intel processor, the need for a new chipset means you can’t save money by keeping your existing motherboard.
That doesn’t mean that Coffee Lake is a duff product, however. There’s ample power here to tear through almost any task, and once the launch period is over, we wouldn’t be surprised to see a price drop to bring Coffee Lake into line with Ryzen. If that happens it will be a very tempting alternative.