Review: Intel Core i7 8700K CPU

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Review: Intel Core i7 8700K CPU

Intel’s 8th Generation Core CPU hits the Labs.

I can’t recall the last time I’ve seen so many new products to hit the market in such a short period of time. We can thank AMD for this, first with its release of the Ryzen CPU, then the unleashing of the Radeon RX Vega GPUs, and finally the uber-chip; the Threadripper. It’s quite incredible to see one company release so many products in such a short period of time, but it’s lit a fire under the butt of the rest of the industry. Nvidia hasn’t responded yet, but Intel certainly has. First its Core-X series of processors with more cores than an apple farm, and now the 8th Generation Core CPU. With two more cores than we’re used to, plus an increase in per-core performance, is it enough to win back the race of best value CPU on the market? 

What’s on the inside?

Formally codenamed Coffee Lake, the new 8th Gen Core CPU has a number of large changes compared to its predecessor. There are six new chips in the 8th Gen range.

As you can see, there’s been quite a price bump with these new CPUs. For example, the i7-8700K is replacing the i7-7700K, which currently retails for just $449 – that’s a hefty 30% increase. However, if overseas prices are to be taken as a reference, we can expect local prices to drop as more stock arrives, with the i7-8700K eventually retailing for around the $520 mark. Eventually most 8th Generation Core CPUs will only cost around 10% more than their existing counterparts.

The biggest difference the table above highlights is the increase in cores in the new i7 and i5 models, which now come with six cores (and twelve threads in the i7), which is a rather hefty increase over the prior generation. Even the i5 series gets the full six cores, but it lacks HyperThreading; it’s only once we hit the budget i3 chips that we move back to a quad-core CPU configuration. 

When it comes to rolling out a new CPU architecture, it’s normal for Intel to adopt the same design across all of its products. This changes in the 8th Gen Core CPUs, with a variety of architectures used across the product range. Right now they’re using the Coffee Lake architecture for the desktop, but we can expect Intel to move the range across to the Cannonlake design early next year, which promises to bring even faster IPC improvements to each core. Yet, the mobile version uses the Kaby Lake R design, an update on last year’s Kaby Lake architecture. This is obviously a sign that Intel is rushing its releases to keep up with AMD, but it makes for a confusing situation for consumers.

Intel vs AMD… again

So we’re seeing Intel slowly catching up to AMD when it comes to core count, but what else has changed with Coffee Lake? Well, it’s being built on an improvement of the 14nm FinFET process of the last generation, which Intel is calling 14nm++, and this has allowed Intel to give these chips quite a decent frequency boost. However, it’s worth noting that the top speeds listed are only when a single core is operating – we found that our i7-8700K stayed at 4.3GHz during benchmarking across all cores. Apparently only the i7 supports Turbo Boost as well, with the other chips missing out. 

These new chips also support per-core overclocking, so you can single out a solo core for overclocking attention, though we’ve seen this feature in earlier CPUs. You’ll still need to buy a K-class CPU to be able to overclock. The integrated GPU on each CPU is identical to Kaby Lake, though apparently frequencies have been increased, but Intel won’t disclose by how much. When it came to overclocking, we managed to hit a stable 4.7GHz, a decent boost over the default boost speed. We should point out that there’s no cooler included with these chips. We used the Corsair H105 AIO cooler to hit these results, but due to the low TDP of this range you won’t need extreme cooling to max out your CPU. 

One disappointment with the new CPUs is that they were previously rumoured to work with the Z270 chipset. Sadly this is no longer true – you’re going to need to buy a new Z370 motherboard if you want to run an 8th Gen Core CPU. This increases the cost of upgrading to the new platform immensely and is a real disappointment. Notice that it’s the Z370 chipset, whereas AMD has the X370. At least the Socket 1151 that it uses is compatible with existing coolers; it’s just a shame that the CPU won’t work with Z270 boards. The Z370 chipset runs DDR4 memory in dual channel mode at 2666MHz, a slight boost from the 2400MHz of the Z270. It also has up to 40 lanes of PCIe 3.0 for peripherals, and there’s built-in support for 4K HDR and Thunderbolt 3.0. Intel has included support for USB 3.1 Gen 1 in the Z370 chipset, so expect to see mobo makers add their own USB 3.1 Gen 2 controllers for additional bandwidth. 

Performance

Intel is claiming a performance boost of up to 40% over its prior mainstream CPU designs, which it says is the largest single increase between CPU generations in the company’s history. Thing is, it’s all due to those extra CPU cores; if your app isn’t multi-threaded, don’t expect anything like that. 

According to our Cinebench single-threaded score, the new i7-8700K scores 201, which is a mere 3% performance increase over the i7-7700K. So when it comes to applications that rely upon one or two cores, don’t expect those levels of performance increase at all. Having said that, when it came to single threaded performance, the i7-8700K basically beat everything, which is especially evident in our gaming tests. Unfortunately it didn’t do so well when it comes to multithreaded apps, where AMD’s Ryzen gave it a thorough beating. 

Best for Gamers

Unless you’re a serious multithreader, we have a new champion when it comes to single core performance. It’s not the fastest by the largest of margins though, and the added cost of a new motherboard doesn’t help matters. If Intel could have released this with Z270 compatibility it’d be a much more compelling argument to upgrade, but right now users are looking at $800 or so to make the switch. It is arguably the best gaming CPU on the market right now, especially once it’s given a good overclock, and yet AMD’s Ryzen points to the way of the future, which is multithreading. Yet that’s a solid year or two away before it becomes the norm, if not even longer, leaving consumers in a confusing place to be right now. 

Core i7 8700K
Verdict
"Unless you’re a serious multithreader, we have a new champion when it comes to single core performance."
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