Ryzen review: AMD is back

AMD's vaunted Ryzen CPU is a multithreaded monster with one glaring weakness.

Admit it. You love underdog tales. The Cleveland Cavaliers coming back from a 3-1 deficit against the Golden State Warriors. The New York Giants defeating the 18-0 New England Patriots, and the Average Joes beating the heavily favored Purple Cobras in the dodgeball finals.

Well, you can now add AMD’s highly anticipated Ryzen CPU to that list of epic comebacks in history. Yes, disbeliever, AMD’s Ryzen almost—almost—lives up to the hype. What’s more, it delivers the goods at an unbeatable price: $499 for the highest-end Ryzen 7 1800X, half the cost of its closest Intel competitor.

But before AMD fanboys run off to rub it into Intel fanboys’ faces, there’s a very important thing you need to know about this CPU and its puzzling Jekyll and Hyde performance. For some, we dare say, it might even be a deal breaker. Read on.

ryzen 2 Gordon Mah Ung

The boxed Ryzen 7 1800X and Ryzen 7 1700X won't come with stocker coolers.

What Ryzen is

We can’t get into a review of Ryzen without first recalling the tragic circumstances that came before it: AMD’s Bulldozer and Vishera CPUs sold under the FX brand. Intended as a competitive comeback to Intel’s own epic comeback chips—the Core 2 and Core i7—AMD’s FX series instead went down in flames performance-wise.

The failure of Bulldozer and Vishera left AMD languishing for years, all but abandoning the high end and nursing itself on an ARM CPU for servers. In fact, the last time AMD had a truly competitive CPU, people still listened to INXS, the Weakest Link was a thing, and George W. Bush was president. The technical term for that is: a hell of a long time ago.

Ryzen is nothing like its star-crossed predecessors though. The FX CPUs used a technique called clustered multithreading (CMT) that shared key components of the chip; they were built on an uncompetitive 32nm, and later 28nm, process; and the 8-core versions more often than not lost to Intel’s 4-core chips.

As anyone who has wallowed in failure only to return knows, tragedy and loss only make an underdog story sweeter. With Ryzen, AMD rebooted its CPU design and tossed aside the CMT design and even adopted a technique from Intel’s playbook called simultaneous multithreading (SMT), which virtualizes CPU resources.

ryzen die shot 1 AMD

AMD’s new Ryzen CPU does away with the shared cores of the FX line in favor of stand-alone cores with simultaneous multithreading.

Whereas AMD’s design once had every two cores share resources, each Ryzen core is now a distinct entity built into a four core complex. In the shot below two core complexes makeup an 8-core Ryzen chip.

ryzen core complex AMD

Each Zen core complex is made up of four individual CPUs. Two of these complexes make up the 8-core Ryen chip in the preceding image.

Also gone are the 32nm process of Bulldozer and the 28nm process of Vishera. Ryzen CPUs are built on a state-of-the-art 14nm process by AMD’s spun-off fab Global Foundries. In short, the core design seems to have set the stage for an AMD return to glory.

ryzen models IDG

AMD’s Ryzen 7 lineup compared to Intel’s CPUs.

Ryzen: Heavy-duty CPU, light-duty chipset

It should be pointed out that Ryzen’s chipset isn’t exactly heavy duty. Because Ryzen is more of a system-on-chip (SoC) than a CPU, it contains many interface features on-chip, which are augmented by a particular AM4 socket chipset (to learn more about the various chipsets, see our guide to choosing an AM4 motherboard.) The upshot is that while Ryzen provides up to eight physical cores, the surrounding infrastructure is more consumer-oriented. Ryzen has 24 PCIe lanes total, 16 of which are dedicated to the GPU. If you go with the highest-end motherboard chipset, the X370, in order to run two video cards, that single x16 is split into two x8 connections. The remaining PCIe lanes can be used by the motherboard maker for NVMe or other I/O options. That’s not much different than what Intel does with the current Core i7-7700K, which also has 16 lanes of PCIe for the GPU. While Intel’s highest-end consumer Z270 chipset appears to have a lot more I/O with up to 24 lanes of PCIe of its own, a bottleneck between the consumer-grade chipset and CPU keep it from being utilized.

For most people there is still plenty of speed on tap with Ryzen and Core i7-7700K. But for those who need insane numbers of PCIe lanes, for, say, multiple NVMe drives that will be used simultaneously, Intel’s Broadwell-E and its X99 chipset have the advantage.

Broadwell-E (and Haswell-E) feature up to 40 lanes of PCIe directly wired to the CPU plus an additional eight lanes of PCIe in the X99 chipset. But again, for the vast majority of consumers, even prosumers, that’s overkill.

ryzen 4 Gordon Mah Ung

In order of appearance: AMD’s FX, an AMD Ryzen, an Intel Core i7-5960X, and an Intel dual-core Kaby Lake CPU.

How fast is it? There’s only one way to find out

If you haven’t followed the news, AMD has already said Ryzen exceeds its goal of a 40 percent increase over previous designs—in fact, it has hit a 52 percent increase in clock-for-clock performance over the Piledriver cores. But no one cares about that. The only thing you want to know is how it does against Intel.

How we tested

For the benchmark-o-rama I set up four separate PCs. All featured clean installs of the latest version of 64-bit Windows 10. Each of the PCs was also built using the same SSD and GPU, and the latest BIOS was used on each board.

I turned to what we believe are Ryzen’s natural competitors: Intel’s $1,089 8-core Broadwell-E Core i7-6900K; the $441 6-core Broadwell-E Core i7-6800K; and the $349 4-core Kaby Lake Core i7-7700K. And, although its well beyond its prime, I also included an 8-core AMD FX-8370, which is currently the top Vishera-based CPU you can get without wading into the crazy range (meaning AMD’s insane FX-9590 chip that only works with a handful of motherboards due to its excessive power consumption).

For the pair of Broadwell-E processors, I tested on an Asus X99 Deluxe II board. I used an Asus Z270 Maximus IX Code for the Kaby Lake chip. I paired the Vishera with an ASRock 990FX Killer. The Ryzen CPUs were tested with an Asus Crosshair VI Hero board. 

I used a Founders Edition GeForce GTX 1080 on all of the builds and the clock speeds were checked for consistency.

ryzen bacik Gordon Mah Ung

The AMD FX on the lower left has more pins than the AMD Ryzen on the lower right. The two Intel chips above put the pins in the socket.

RAM configuration

I opted to test each with 32GB of RAM with the memory controllers fully loaded using standard JEDEC-speed RAM. On the Ryzen and Kaby Lake systems, that meant four DIMMs of DDR4/2133 for a total of 32GB of RAM. The Broadwell-E systems were stuffed with eight DIMMS of DDR4/2133 for a total of 32GB RAM. The FX CPU had four DDR3/1600 DIMMS in it for a total of 32GB of RAM. The Ryzen, Kaby Lake, and FX machines were in dual-channel mode, whereas the Broadwell-E box was in quad-channel mode.

Cooling configuration

One final disclosure: I expected  to test all the builds using closed-loop coolers. But because AMD didn’t send me a CLC for Ryzen until late into testing, I had to test all the PCs using air cooling. AMD fans might suspect this of hobbling the Ryzen parts, which have a mode called eXtended Frequency Range (XFR) that allows the chip to clock up to the capabilities of the cooler.

I should add here that XFR only really adds up to 100MHz to the chip’s speeds today. The Ryzen 7 1800X on XFR, for example, would hit 4.1GHz over its Precision Boost speed of a 4GHz. The Noctua air cooler I used is itself fairly burly cooler and I did see XFR speeds kicking in on occasion.

OK, ready for some testing? Then read on

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Gordon Mah Ung

Gordon Mah Ung

PC World (US online)
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