Official Intel 7th-gen Kaby Lake Review: One big change makes up for smaller ones

Don’t dismiss Intel’s newest CPU with a meh just yet. There’s more to the chip than you expect.

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The back of a Kaby Lake CPU.

The IPCs have it

CPU nerds like to talk about IPC, or instructions per cycle of a CPU. It’s one way to gauge efficiency at a given clock speed. I took the performance of each CPU running the CineBench R15 test in single-threaded mode with Turbo Boost switched off on all of the CPUs. As I said with the Skylake Core i7-6700K review, it’s a pretty sobering wakeup call to see just how slowly IPC is inching along in modern CPUs. 

kaby lake cinebench locked at 2.5ghz ipc PCWorld

With all five CPUs locked at 2.5GHz, you can see the efficiency of each has only slowly increased.

The good news for modern processors is IPC isn’t the only place you can pick up performance. Clock speed, core count and ability to hold Turbo Boost speeds longer (thanks to improved manufacturing) have all added up to better performance. Here’s that reminder seen in the first chart we ran from Cinebench R15, when each CPU is allowed to run unfettered rather than locked down to a fixed frequency. 

kaby lake cinebench multi threaded PCWorld

Clock speeds, core count and process keeps performance moving along.

Overclocking performance

Many of the early unsanctioned reviews of Kaby Lake gave it a black mark for generating excessive heat when overclocked.

I myself have always been reluctant to offer judgment about the overall overclocking performance of an entire CPU series when working with a sample of one. Combine that with new motherboards, new BIOSes and the dizzying amount of mistakes a reviewer can make, and you can see why I think it’s unfair to decide on an entire line based on one CPU and early motherboards.

Still, in an attempt to get a feel for how Kaby Lake will overclock for most, I spoke to two PC OEMs and a motherboard maker who have been trying to overclock the CPU for far longer and with far more samples.

The Kaby Lake results they’ve seen were quite good. Many of their chips hit 5GHz or got very close.

Motherboard maker Asus in fact, will feature overclocking profiles that should make overclocking a lot simpler. 

"Through rigorous testing, ASUS engineers have fine-tuned a profile that allows Kaby Lake CPUs to overclock to 5GHz with an 80 percent success rate," the company said.

maximus ix hero 3d 1 Asus

Asus said its new Z270 motherboards should be able to overclock Intel's new 7th generation Kaby Lake CPUs to 5GHz with an 80 percent success rate.

This is actually a great sign for practical overclockers because 5GHz overclocks haven’t been seen since the days of the Core i5-2500K and Core i7-2600K. Both of which could seemingly run at 4.5GHz on air or 5GHz with liquid cooling.

You can’t say the same about the CPUs that followed Sandy Bridge. Ivy Bridge, and Haswell both hit walls at 4.5GHz for most people. Devil’s Canyon was supposed to break the 4.5GHz barrier but all we got were chips that could get closer to 4.5GHz but not surpass it. Broadwell didn’t count (it didn’t ship in great volume), and Skylake also hit that same invisible barrier at 4.5GHz.

With its massaged 14nm process, Kaby Lake finally seems to break that magical barrier. To prove it, I had Digital Storm and Falcon Northwest send two production PCs that could break the 4.5GHz barrier.  Both did. The Digital Storm system, for example, was able to withstand almost four hours of continuous Handbrake encodes with all cores locked at 5GHz without issue. The Falcon Northwest machine could hit 5GHz in a small-form-factor box.

kaby lake cinebench multi threaded oc PCWorld

Here’s what you should expect from a Kaby Lake running at 5GHz.

Running at 5GHz, the Kaby Lake will match a six-core Ivy Bridge-E in performance. In single-threaded applications at 5GHz, the results are even more impressive.

kaby lake cinebench single threaded oc PCWorld

A Kaby Lake running at 5GHz in single-threaded tasks will be tough to beat.

Does this mean your chip will hit 5GHz? No. Remember, it’s always been a lottery system with overclocking results, but the word from experienced boutique PC builders and Asus is far more promising than it's been in a long time.

As much as everyone wants to be a hater, it’s looking very much like Kaby Lake, for those who want to go there, can break 4.5GHz at last.

Umm, how much again?

So we have an official, sanctioned view of just how a desktop Kaby Lake performs. Now, what everyone wants to know is how much. There is, again, more disappointment.

The initial prices the press was given for Kaby Lake CPUs would have made the Core i7-7700K, at $305, the cheapest Core i7 “K” CPU the company has ever produced. It was low enough that I mapped out the price of the chip in a chart and was prepared to write that the CPU price war had already begun with AMD over its upcoming Ryzen

kaby lake pricing PCWorld

The initial price of the Core i7-7700K we were given would have been the cheapest Core i7 “K” CPU in history. Unfortunately, that turned out to be wrong.

Alas, it was all wrong. Intel updated its price sheets, increasing the price to $339. That’s the same price as the Haswell, Devil’s Canyon and Skylake Core i7 chips launched at.

In defense of Intel, every new chip in the price list went up by $34 to $63. Even laptop CPUs, where Intel essentially has no competition from AMD today, increased. So maybe this was truly just an across-the-Excel formula error and not a reason that's spelled Ryzen. Clearly, though, the price war with AMD isn’t kicking off with Kaby Lake.


So let’s sum it up. In laptops, the performance bump is very decent, with perhaps 20 percent or more going from just Broadwell to Kaby Lake. 

Desktops aren’t constrained by thermals and battery life the way laptops are, so the performance difference between the generations is far less. The one really big difference between previous chips is the greatly improved video engine. To performance-oriented desktop users, though, integrated graphics—outside of NUC-style mini-PC’s—is unimportant.

The price, though equal to Skylake, is a little disappointing for those who expected it to be cheaper, but it’s not like you’re paying more for less performance. Instead, you’re paying the same price to get a little better performance.

Kaby Lake is better and faster, but despite the greater overclocking potential, you can see why, for most DIYers, it’s a little bit of a yawn. Still, some builders should consider it, and I break down the decision tree CPU by CPU below.

kaby lake Gordon Mah Ung

Kaby Lake is a drop-in replacement for Skylake. I’m just not sure anyone should or would do that.

If I had a Core i7-6700K system: I wouldn’t upgrade to Kaby Lake, and I don’t think Intel expects you to unless you want to help prop up the company’s bottom line. There’s just absolutely nothing compelling that would warrant it on a discrete graphics system right now. If Intel’s Optane emerges as a game changer, then you'd consider a move.

If I were going to build a new Core i7-6700K system: I wouldn’t. Instead, I’d build one using the new Core 7-7700K. Even if you don’t intend to overclock it at first, the stock clock is already higher, and prices will be the same once initially demand settles down. The simple math is Kaby Lake is better, so there’s no reason to buy Skylake today.

If I had a Core i7-4770K or Core i7-4790K system: I probably wouldn’t upgrade. The Core i7-4770K is still quite a powerful and useful CPU. The only reason would be the need for more M.2 or U.2 storage options, or if you want to be ready for Optane.

If I had a Core i7-4960X or Core i7-3960X system: The results are pretty clear for these elderly CPUs: Even a once mighty six-core CPU can now be matched by Intel’s new Core i7-7700K chip in some workloads. However, if you were the kind of person who bought a six-core Sandy Bridge-E or Ivy Bridge-E, you care about core count for a reason. It makes far more sense to buy into Intel’s Broadwell-E platform to run a six-core or eight-core CPU. Or just wait to see if AMD’s Ryzen can give you the core counts and performance you need.

If I had a Core i7-3770K or Core i7-2600K: Look, there’s nothing wrong with the classic Core i7-3770K or Core i7-2600K in actual CPU performance. The problem is your chipset. The Z77 chipset only has two SATA 6Gbps ports, and good luck trying to run a modern M.2 NVMe drive in them. These platforms are about as creaky as a Pontiac Grand Am with 275,000 miles on the odometer and a leaky transmission. It’s basically time to upgrade, and Kaby Lake would be fine for both.

If I had a Core i5: You can get by with a quad-core without Hyper-Threading but anecdotal reports from many say the days of a quad-core only CPU are drawing to a close. And if you have to upgrade your Sandy Bridge or Ivy Bridge Core i5 chip (or even Haswell or Skylake) it probably makes sense to upgrade all the way to a new Kaby Lake CPU.

If I had an AMD FX-9590: Well yes, an upgrade to Kaby Lake for your AMD “eight-core” would be a very nice but let’s face it, there’s a reason you’re rolling one of AMD’s top CPUs—you’re an AMD fan. Just wait to see if AMD’s Ryzen materializes and offers the price-to-performance ratio people are hoping for so you can continue to fly the white, black and green flag. If Ryzen does falter out the gate (unlikely) then yes, a shiny Kaby Lake might be in your future.

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