Saturday, February 11


A Moment Of Zen

Back in 2011, AMD released Bulldozer, the follow-up to their well-regarded Athlon and Phenom processors which were getting a bit long in the tooth.  Bulldozer changed the traditional design AMD had used, of four or six independent cores, two four modules containing two cores each, with some shared resources like caches and schedulers.

This was not a roaring success, for a number of reasons:
  • AMD could not hit their frequency targets within their power targets.  They've had a 5GHz chip for years, but it's a 220W monster, and they've had low-power chips, but they're slow.
  • Although the shared resources made for smaller cores and good multi-threaded throughput, single-threaded performance was significantly behind Intel's chips, and that matters both for common business applications and for gaming.
  • AMD's plans were to use future process improvements - 20nm planar and then 14nm FinFET - to increase the number of cores and reduce power consumption.  But the 20nm planar process was an industry-wide failure, and AMD's high-end CPUs have been stuck at 32nm for five years.  Intel alone escaped this because they spent the extra money to go to FinFET in their 22nm process.
AMD quickly realised that they had a non-flying turkey on their hands and they needed to do something about it.  In fact, they did two things: A series of updates to Bulldozer that gradually improved performance (though never quite enough), and at the same time, a crash project to build an all-new no-compromise CPU with none of Bulldozer's limitations.

That new processor was called Zen - now branded Ryzen - and it's about to hit the computer market like a brick through a fish tank.

It's eight cores again, but unlike Bulldozer, Zen cores don't share resources.  Instead, each Zen core can run two threads, the same Intel's hyperthreading, so the eight-core chip looks to your operating system like sixteen cores.

It will compete with Intel's $1099 eight-core i7 6900K, and it will cost around $319, and use half the power of the Intel chip.

They'll also be shipping six-core and four-core chips to compete with Intel's Core i5 and i3, and a 32-core monster called Naples for servers, and a mid-range 16-core version called Snowy Owl.

Later this year they'll add a desktop chip with integrated graphics faster than the Playstation 4 (though not as fast as the Playstation Pro).

They have a new socket for these chips, AM4, which supports all versions of their desktop CPUs, from 4 to 8 cores, with or without integrated graphics.

Official launch is expected at GDC 2017, which starts February 27.  Since that's very soon now, it means devices must already be shipping to distributors, and that means that AMD's previously tight control over detailed specs and prices has sprung a thousand leaks in the past week.

On other thing to note: The R7 1700 model  - the $320 8-core version, running at around 3.1GHz with a 3.7GHz turbo clock - is a 65W part, where Intel's 6900K is a 140W part.  What's more, it ships with AMD's excellent Wraith cooler, designed for their existing 125W chips, and its clock speeds are completely unlocked for overclocking.  That should make it a very popular part for enthusiasts.

It also means that AMD could plausibly ship even more cores if they want to.  Even with 8 cores, the chip is estimated to only be around 220mm2; 12 cores would be less than 300mm2 and run at less than 95W at the same clock speeds, and would completely obliterate Intel's mainstream desktop parts in any multi-threaded workload.

Intel has had the desktop CPU market to itself for five years and progress has slowed to a crawl, but it looks like we're about to get five Christmases all at once.

Posted by: Pixy Misa at 11:31 PM | Comments (5) | Add Comment | Trackbacks (Suck)
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1 So add the cost of a new motherboard for the new socket too....

Posted by: Mauser at Sunday, February 12 2017 06:20 AM (5Ktpu)

2 Necessary, though.  AMD's existing motherboards only supported older DDR3 memory, and the new socket allows for more PCIe lanes, more video outputs, and built-in I/O for USB 3, SATA, and Ethernet.

Also, Intel sell different (and expensive) motherboards for their 8-core CPUs, and change sockets every 2-3 years anyway.

AMD have been much better at this; for 10 years they've supported compatibility between one degree of difference in motherboard and CPU versions.  So an AM2+ CPU would work in an older AM2 socket, and an AM3 CPU works in an AM3+ socket.  Not true this time - this is a brand new design with about 400 extra pins - but should work whenever AM4+ ships.

Posted by: Pixy Misa at Sunday, February 12 2017 06:38 AM (PiXy!)

3 If this new line is even close to what the benchmarks say it's going to put some serious hurt on Intel.  There's speculation Intel's already running scared by pulling the 8th-gen Core chips from 2018 into 2H2017.
With the lead time on chip design, all these look like they're likely to be is Kaby Lake rev 2, that is, a couple hundred MHz faster (based on the claim of a ~15% improvement, which is roughly comparable to KL's increase over Skylake (entirely due to clock speed increases; at the same speed, SL and KL perform essentially identically.)
AMD must've been working on this for a LONG time, even before they started talking about Zen.
It's almost time for me to upgrade my home desktop.  I had been going back and forth between a 5820K and a 7700K (I want the additional cores for things like VMing, but I also want a small case (currently loving the look of the NZXT Manta) but there's only one Mini ITX X99 motherboard, and it seems to be a crapshoot: if it works, it's great, but a LOT of people have serious problems with it) but now I'm going to hold off until sites like AnandTech (I saw you commenting there yesterday, Pixy) and HardOCP get their hands on Ryzens and test them.  I am training myself to admit I don't NEED the absolute fastest single-core performance for nearly anything I do.

Posted by: Rick C at Monday, February 13 2017 10:14 AM (ITnFO)

4 Yeah, they started work on Zen mid 2012.  It takes a while to build a whole new CPU.

According to Wikipedia, quad-core chips will start at $129, six-core at $220, and eight-core at $319.  Top of the line eight-core 4GHz model is $499.

Posted by: Pixy Misa at Monday, February 13 2017 01:31 PM (PiXy!)

5 Based on early Passmark benchmarks, the R7 1700X has 87% of the single-threaded performanced of the i7 6700K (2046 vs. 2343). The 1800X should work out to about 92%.  The 7700K is a bit faster, but not hugely so.

It looks like AMD are where they needed to be. The FX-8350 suffered from nearly 40% slower single-threaded performance, and limited multi-threaded scaling despite having eight cores. Zen seems to have fixed both the single-threaded performance and the multi-threaded scaling.

Motherboard pricing has started showing up too, essentially in line with Intel's mainstream boards, but a lot cheaper than the boards for their eight-core chips.

Posted by: Pixy Misa at Tuesday, February 14 2017 10:06 AM (PiXy!)

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Apple pies are delicious. But never mind apple pies. What colour is a green orange?

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