Talking 12nm and Zen+

One of the highlights of the Ryzen 2000-series launch is that these processors use GlobalFoundries’ 12LP manufacturing process, compared to the 14LPP process used for the first generation of Ryzen processors. Both AMD and GlobalFoundries have discussed the differences in the processes, however it is worth understanding that each company has different goals: AMD only needs to promote what helps its products, whereas GlobalFoundries is a semiconductor foundry with many clients and might promote ideal-scenario numbers. Earlier this year we were invited to GlobalFoundries Fab 8 in upstate New York to visit the clean room, and had a chance to interview Dr. Gary Patton, the CTO.

The Future of Silicon: An Exclusive Interview with Dr. Gary Patton, CTO of GlobalFoundries

In that interview, several interesting items came to light. First, that the CTO doesn’t necessarily have to care much about what certain processes are called: their customers know the performance of a given process regardless of the advertised ‘nm’ number based on the development tools given to them. Second, that 12LP is a series of minor tweaks to 14LPP, relating to performance bumps and improvements that come from a partial optical shrink and a slight change in manufacturing rules in the middle-line and back-end of the manufacturing process. In the past this might not have been so news worthy, however GF’s customers want to take advantage of the improved process.

Overall, GlobalFoundries has stated that its 12LP process offers a 10% performance improvement and a 15% circuit density improvement over 14LPP.

This has been interpreted in many ways, such as an extra 10% frequency at the same power, or lower power for the same frequency, and an opportunity to build smaller chips.

As part of today’s launch, AMD has clarified what the move to 12LP has meant for the Ryzen 2000-series:

  1. Top Clock Speeds lifted by ~250 MHz (~6%)
  2. All-core overclocks around 4.2 GHz
  3. ~50 mV core voltage reduction

AMD goes on to explain that at the same frequency, its new Ryzen 2000-series processors draw around 11% less power than the Ryzen 1000-series. The claims also state that this translates to +16% performance at the same power. These claims are a little muddled, as AMD has other new technologies in the 2000-series which will affect performance as well.

One interesting element is that although GF claims that there is a 15% density improvement, AMD is stating that these processors have the same die size and transistor count as the previous generation. Ultimately this seems in opposition to common sense – surely AMD would want to use smaller dies to get more chips per wafer?

Ultimately, the new processors are almost carbon copies of the old ones, both in terms of design and microarchitecture. AMD is calling the design of the cores as ‘Zen+’ to differentiate them to the previous generation ‘Zen’ design, and it mostly comes down to how the microarchitecture features are laid out on the silicon. When discussing with AMD, the best way to explain it is that some of the design of the key features has not moved – they just take up less area, leaving more dark silicon between other features.

Here is a very crude representation of features attached to a data path. On the left is the 14LPP design, and each of the six features has a specific size and connects to the bus. Between each of the features is the dark silicon – unused silicon that is either seen as useless, or can be used as a thermal buffer between high-energy parts. On the right is the representation of the 12LP design – each of the features have been reduced in size, putting more dark silicon between themselves (the white boxes show the original size of the feature). In this context, the number of transistors is the same, and the die size is the same. But if anything in the design was thermally limited by the close proximity of two features, there is now more distance between them such that they should interfere with each other less.

For reference, AMD lists the die-size of these new parts as 213mm2, containing 4.8 billion transistors, identical to the first generation silicon design. AMD confirmed that they are using 9T transistor libraries, also the same as the previous generation, although GlobalFoundries offers a 7.5T design as well.

So is Zen+ a New Microarchitecture, or Process Node Change?

Ultimately, nothing about most of the Zen+ physical design layout is new. Aside from the manufacturing process node change and likely minor adjustments, the rest of the adjustments are in firmware and support:

  • Cache latency adjustments leading to +3% IPC
  • Increased DRAM Frequency Support to DDR4-2933
  • Better voltage/frequency curves, leading to +10% performance overall
  • Better Boost Performance with Precision Boost 2
  • Better Thermal Response with XFR2
New CPUs, New Process, New Competition Improvements to the Cache Hierarchy: Lower Latency = Higher IPC
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  • Marlin1975 - Thursday, April 19, 2018 - link

    Looks good, guess AMD will replace my Intel system next.

    Just waiting for GPU and memory prices to fall.
    Reply
  • 3DoubleD - Thursday, April 19, 2018 - link

    Agreed... the waiting continues Reply
  • WorldWithoutMadness - Thursday, April 19, 2018 - link

    Lol, you might even wait until Zen 2 comes out next year or even later. Reply
  • Dragonstongue - Thursday, April 26, 2018 - link

    should be out next year as AMD has been very much on the ball with Ryzen launches more or less to the DAY they claimed would launch which is very nice...basically what they are promising for product delivery they are doing what they say IMO, not to mention TSMC recently announced volume production of their 7nm, so that likely means GloFo will be very soon to follow, and AMD can use TSMC just the same :) Reply
  • t.s - Tuesday, July 31, 2018 - link

    What @WWM want to say is: You can wait forever for the RAM price to go down, rather than when ryzen 2 out. Reply
  • StevoLincolnite - Thursday, April 19, 2018 - link

    I still haven't felt limited by my old 3930K yet.

    Can't wait to see what Zen 2 brings and how Intel counters that.
    Reply
  • mapesdhs - Friday, April 20, 2018 - link

    If you ever do fancy a bit more oomph in the meantime (and assuming IPC is less important than threaded performance, eg. HandBrake is more important than PDF loading), a decent temporary sideways step for X79 is a XEON E5-2697 v2 (IB-EP). An oc'd 3930K is quicker for single-threaded of course, but for multithreaded the XEON does very well, easily beating an oc'd 3930K, and the XEON has native PCIe 3.0 so no need to bother with the not entirely stable forced NVIDIA tool. See my results (for FireFox, set Page Style to No Style in the View menu):

    http://www.sgidepot.co.uk/misc/tests-jj.txt
    Reply
  • mapesdhs - Monday, April 23, 2018 - link

    Correction, I meant the 2680 v2. Reply
  • Samus - Friday, April 20, 2018 - link

    I never felt limited by my i5-4670k either, especially mildly overclocked to 4.0GHz.

    Until I build a new PC around the same old components because the MSI Z97 motherboard (thanks MSI) failed (it was 4 years old but still...) so I picked up a new i3-8350k + ASRock Z270 at Microcenter bundled together for $200 a month ago, and it's a joke how much faster it is than my old i5.

    First off, it's noticeably faster, at STOCK, than the max stable overclock I could get on my old i5. Granted I replaced the RAM too, but still 16GB, now PC4-2400 instead of PC3-2133. Doubt it makes a huge difference.

    Where things are noticeably faster comes down to boot times, app launches and gaming. All of this is on the same Intel SSD730 480GB SATA3 I've had for years. I didn't even do a fresh install, I just dropped it in and let Windows 10 rebuild the HAL, and reactivated with my product key.

    Even on paper, the 8th gen i3's are faster than previous gen i5's. The i3 stock is still faster than the 4th gen i5 mildly overclocked.

    I wish I waited. It's compelling (although more expensive) to build an AMD Ryzen 2 now. It really wasn't before, but now that performance is slightly better and prices are slightly lower, it would be worth the gamble.
    Reply
  • gglaw - Saturday, April 21, 2018 - link

    i think there's something wrong with your old Haswell setup if the difference is that noticeable. I have every generation of Intel I7 or I5 except Coffee Lake running in 2 rooms attached to each other, and I can't even notice a significant difference from my SANDY 2600k system with a SATA 850 Evo Pro sitting literally right next to my Kaby I7 with a 960 EVO NVMe SSD. I want to convince myself how much better the newer one is, but it just isn't. And this is 5 generations apart for the CPU's/mobos and using one of the fastest SSD's ever made compared to a SATA drive, although about the fastest SATA drive there is. Coffee Lake is faster than Kaby but so tiny between the equivalent I7 to I7, I can't see myself noticing a major difference.

    In the same room across from these 2 is my first Ryzen build, the 1800X also with an 960 EVO SSD. Again, I can barely convince myself it's a different system than the Sandy 2600k with SATA SSD. I have your exact Haswell I5 too, and it feels fast as hell still. Especially for app launches and gaming. The only time I notice major differences between these systems is when I'm encoding videos or running synthetic benchmarks. Just for the thrill of a new flagship release I just ordered the 2700X too and it'll be sitting next to the 1800X for another side by side experience. It'll be fun to setup but I'm pretty convinced I won't be able to tell the 2 systems apart when not benchmarking.

    Reply

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