PCIe 4.0 to hit 16 GT/s; base spec due in 2014-2015

As the first PCI Express 3.0-compatible motherboards slowly begin to seep into the marketplace, the next major revision of the interconnect is already in the works. PCI-SIG, which is responsible for developing the PCI Express spec, has announced some preliminary details about PCIe 4.0.

For starters, PCI-SIG says it has decided on a transfer rate of 16 GT/s for the next-generation interconnect. A feasability study purportedly showed that 16 GT/s can be achieved over copper wires, at roughly the same power levels as PCIe 3.0, using chips fabbed with “mainstream silicon process technology.” The speed increase won’t compromise backward-compatibility with previous iterations of the PCIe spec, either, so today’s PCIe devices should work just fine in PCIe 4.0 slots (and vice versa).

PCI-SIG doesn’t mention which encoding scheme the upcoming standard will use. Assuming the same 128b/130b system as with PCIe 3.0, a 16 GT/s peak transfer rate would translate into per-lane, per-direction bandwidth of just under 2GB/sβ€”a two-fold increase over the PCIe 3.0 standard, and nearly four times as fast as PCIe 2.0. You’d be looking at about 31.5GB/s per direction for a PCIe 4.0 x16 slot.

While the transfer rate increase is the biggest news, PCI-SIG’s priorities also include reducing power consumption and keeping costs in check. The group says it plans to “investigate advancements in active and idle power optimizations” with PCIe 4.0. In addition, PCI-SIG expects the upcoming spec to “address the many applications pushing for increased bandwidth at a low cost”β€”including, it says, desktops, notebooks, and tablets. PCIe 4.0 looks poised to become just as much of a mainstream interconnect as current iterations of the standard.

The bad news is that you’ll have to wait a few more years for PCIe 4.0-enhanced devices. PCI-SIG doesn’t plan to have the specification completed before “the 2014-2015 timeframe,” and it may take at least another year until the first compliant products hit stores. For reference, the PCIe 3.0 base spec was made public just over a year ago. Although some of today’s motherboards are compatible with it, I’m not aware of any commercial devices that actually take advantage of PCIe 3.0’s higher bandwidth ceiling right now.

Comments closed
    • sschaem
    • 8 years ago

    It was a big fight back in 2002 to get nvidia, ATI, Intel and Microsoft to improve link performance.. what a long way we have come.

    And yep, it was Techreport that cracked the case : [url<]https://techreport.com/articles.x/3977[/url<]

    • Anarchist
    • 8 years ago

    soon … the concept of motherboard may become obsolete …

    • Arclight
    • 8 years ago

    Yawn, we all know PCI-E 6.1 is the real deal.

    • Anomymous Gerbil
    • 8 years ago

    Remember when motherboard makers had trouble designing boards that would work at 25MHz (or 33MHz, etc), e.g. back in the days of DX2/50 CPUs?

    It seems somewhat miraculous that it was once bleeding-edge engineering to get reliable 25MHz signalling on mobo traces, yet soon we’re talking about 640 times faster than that.

    • ronch
    • 8 years ago

    By the time this hits the market I hope the ‘can it run crysis’ crap people ask will have died and never resurrected.

    • Krogoth
    • 8 years ago

    PCIe 3.0 still doesn’t matter for normal desktops. There’s still no killer application for normal desktops that demands more bandwidth then what PCIe 1.0 can muster.

    PCIe 2.0 is just starting to show-up in non-video cards……

    It will be still a while for non-video PCIe 3.0 cards to show up. The only area where it will have tangible benefits are high-end SSD cards.

      • TREE
      • 8 years ago

      Actually I disagree with this. Games that utilise streaming architectures are at their limits with pci express. The available bandwidth between the GPU and system memory is much smaller than that of a modern day console, which utilise Rambus designed system bus, and and can be one of the major performance limitations on a PC. Furthermore the latency of sending data across the PCI-E bus is somewhat slow once compared to consoles.

      The PC with all it’s powerful hardware is going to need to switch to a more expensive, but but faster lower latency bus than PCI-E in future. Otherwise games will keep on stuttering in a lot of cases as they’re already starting to do…

        • bcronce
        • 8 years ago

        Most high end GPUs can barely take advantage of even 8x PCIe2 links. There have been benchmarks where they used a 4x PCIe2 with a 5870 and it had only about a 10% increase going to 8x and sub 2% going to 16x.

        Bandwidth isn’t the issue, it’s latency, but there isn’t much they can do about that.

        I’ll never turn down more speed though.

      • Geistbar
      • 8 years ago

      I think it’s worth noting that due to the way PCIe is handled, there is virtually zero consumer hassle over updated versions. If you combine that with PCI-SIG staying ahead of the necessary transfer rates, it’s caused about 8 years of stability with the standard- something very impressive.

      Or, looking at it another way. Sure, they could stop updating the speed now. All that means is that when devices start to need the increased bandwidth, it isn’t available at all, because they waited until it was needed. All other things being equal, I would much rather have part of my computer faster than it needs to be than have it slower than it needs to be.

        • Bensam123
        • 8 years ago

        Yup, once they start down the ‘lets slow down and wait for things to catch up’ it’s all proverbially down hill from there. It’s not necessary that it’s infeasible to slow things down, but rather it triggers a lethargic mindset and people become stuck in their ways or lack of them.

        I’d prefer progress over lack of progress any day. As long as there is no real downside I don’t see why they can’t keep doing this. They’re even making things backwards compatible with everything else. Remember when ISA was replaced by PCI which they got a AGP slot in addition to that and then was replaced by PCI-E? We still have PCI slots lingering around. You can throw the PCI-X slot in there and all it’s weird versions too if you want to.

        This is why I really abhor where things are going with video games. Not to use this as a stepping stone, but the lethargy of lack of graphical updates is relatively the same thing there. While bad games were made with good graphics, we now have bad graphics with bad games. It then turns into a chicken and an egg problem. Who should make a change first?

      • bcronce
      • 8 years ago

      Less of an issue of improving the performance of a 16x slot as trying to improve the performance of 1x links. With memresistors coming out in a few years, by the time PCIe4 makes it way out, I wouldn’t doubt 1GB/sec+ SSDs using 1x PCIe links over cables.

        • Farting Bob
        • 8 years ago

        [quote<]With memresistors coming out in a few years[/quote<] Luckily for us though memresistors have been 2-3 years away from the last decade, so we've probably got another 8-10 years of them nearly coming out.

          • bcronce
          • 8 years ago

          memresistor based SSDs have been announced for 2013 and DDR3 memory for 2014. They are in the process of making the machines to mass-produce.

          A company won’t spend hundreds of millions of dollars on fab equipment unless they think they’re ready.

          • MadManOriginal
          • 8 years ago

          Memristors were purely theoretical until 2008, that was when HP was the first company to produce working memristors [i<]at all[/i<]. So they haven't been '2-3 years away for the last decade' they didn't even physically exist until 3 years ago.

      • MadManOriginal
      • 8 years ago

      You should have just upvoted post #7 and replied with a simple ‘+1’ post.

    • shank15217
    • 8 years ago

    Mellanox Connect-X 3 cards supports PCI-E 3.0 specs and they are available now, I know cause we own a couple.

    [url<]http://www.mellanox.com/related-docs/prod_adapter_cards/ConnectX3_VPI_Card.pdf[/url<]

      • indeego
      • 8 years ago

      Support doesn’t mean saturate. What devices do you have that saturate 31.5+ GB/s off those cards?

        • Waco
        • 8 years ago

        ~16 GB/s before overhead on PCIe 3.0. I, for one, would be happy to have PCIe 3.0 in every server I work with ASAP. The cards I’ve worked with max out a PCIe 2.0 x16 slot without even breaking a sweat.

          • indeego
          • 8 years ago

          [url=http://www.pcisig.com/news_room/faqs/pcie3.0_faq/#EQ2<]Oh.[/url<]

    • Hattig
    • 8 years ago

    2016: PCIe 5.0 to his 32GT/s; base spec due in 2019-2020.

    As the first PCI Express 4.0-compatible motherboards slowly begin to seep into the marketplace, the next major revision of the interconnect is already in the works. PCI-SIG, which is responsible for developing the PCI Express spec, has announced some preliminary details about PCIe 5.0.

      • chuckula
      • 8 years ago

      We have to go back… TO THE FUTURE!

      • entropy13
      • 8 years ago

      This would be the final reincarnation of the PCIe. After that it would be the HyperPort, which could be “adjustable”, depending on its intended use. The HyperPorts would essentially be at x16 by default, but could be extended to x32, or reduced to x8 and x4. We are talking physically “adjustable” slots here. This would be due around 2024.

    • merkill
    • 8 years ago

    sure we cant use this bandwith atm
    But if motherboardmakers can put in 8x instead of 16x and save a bit of cash , without loosing performance that means cheaper mobos for us all πŸ™‚

    So higher bandwith per lane is always welcome , if we can use it great , if not then fewer lanes get the job done and cash saved πŸ™‚

      • Farting Bob
      • 8 years ago

      16x will always be the standard (along with a few 1x thrown in) mobo’s have, from the most expensive to the cheapest. Their are people out there who would see “8x PCIE 4.0” as rubbish compared to “16x 3.0”. And board makers wont take that risk. The few pence saved by only using an 8x slot will not be worth losing even a single sale over.

        • OneArmedScissor
        • 8 years ago

        Before you know it, laptop cards will be outselling desktop cards, at which point the format will be up in the air.

        It’s highly possibly they could move to connecting with a PCIe cable, as is intended to be done with storage.

    • gmskking
    • 8 years ago

    Thanks, update me again in 3 years.

    • spigzone
    • 8 years ago

    Man, I can’t wait to surf the internet with a PCIe 4.0 motherboard/32 core 6GB/s Fusion chip/Radeon 9990 GPU/Sata IV 4TB SSD combo!!!!!

      • dpaus
      • 8 years ago

      Meh… Krogoth not impressed.

    • barich
    • 8 years ago

    I like the theoretical backwards/forwards compatibility with PCIe. Not requiring new slots/new cards is nice.

    Except when it doesn’t work, like when PCIe 2.1 cards won’t work with the Radeon Xpress 200 chipset. I’m sure I’m one of a very small number of people trying to install a Radeon 5670 in that old of a computer, but it was dual-core and had 4 GB of RAM, so it would have run modern games relatively decently had the card worked.

    • ModernPrimitive
    • 8 years ago

    Whew… worse than waiting on the next DC Comic to Big Screen work of art…. πŸ˜‰

    • chuckula
    • 8 years ago

    Yawn… wake me up when it can do 100 GKT/s (Giga Krogoth Trolls / second)

      • NeelyCam
      • 8 years ago

      So, now that Yawn got the SSD prices down to $1/GB, you expect this?

      Let the poor guy have a break for a change..

        • Meadows
        • 8 years ago

        I wasn’t going to minus you down, but I noticed you had a positive score, so I felt compelled.

          • theonespork
          • 8 years ago

          You just can’t keep the NeelyCam down, but I shall sheepishly follow suit and eliminate his current +1. Sadly, I don’t even know why…

          • entropy13
          • 8 years ago

          What you and theonespork did doesn’t seem to be working. LOL

            • Meadows
            • 8 years ago

            Yes, I’m disappointed.

      • MadManOriginal
      • 8 years ago

      For the first time ever on TR I am tempted to make extra fake accounts just for voting purposes…and in this case they would all be + votes πŸ™‚

      I literally LOL’d (yes, in caps even) after reading your post! Thanks πŸ™‚

      • entropy13
      • 8 years ago

      100 GKT/s? Meh… Krogoth STILL not impressed.

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