1 Reply Latest reply on Oct 27, 2017 11:03 AM by black_zion

    PCI Express 4.0 Standard Officially Released


      Start Your Engines: PCI Express 4.0 Standard Officially Released - ExtremeTech


      As of now, the PCI Express 4.0 standard has been finalized and officially released. The new protocol promises twice the per-lane bandwidth of PCI Express 3.0, allowing a GPU or other accelerator to transfer up to 64GB/s in a duplex x16 link. It’s also been a long time coming.

      Initially, PCIe evolved relatively quickly. It debuted in 2003 with up to 8GB/s of bandwidth in full duplex mode (that’s 4GB/s of bandwidth in either direction, 8GB/s simultaneously). PCI Express 2.0 bumped that to 8GB/s unidirectional and 16GB/s bi-directional in 2005 and PCI Express 3.0 hit 32GB/s of bi-direction bandwidth (16GB/s in each direction) in 2010. PCI Express 4.0, however, had a much longer development period due to the difficulty of continuing to deliver a doubling of bandwidth in a backwards-and-forwards compatible electrical interface and mechanical form factor. Al Yanes, chairman and president of PCI-SIG, has released a blog post (PDF) detailing the advances of the new standard. New capabilities include:

      • Extended tags and credits for service devices
      • Reduced system latency
      • Lane margining
      • Superior RAS capabilities
      • Scalability for added lanes and bandwidth
      • Improved I/O virtualization and platform integration

      In the past, we’ve often talked about PCIe strictly in terms of full-sized desktop GPUs, but that understates the benefit of these technologies. First of all, single GPU systems rarely get much benefit from higher PCI Express speeds, at least not initially. Multi-GPU systems, in contrast, can benefit more from these high-speed links because in these cases, PCIe is explicitly used for cross-GPU communication. We’ve put together a slideshow of the benefits and advances in PCI Express over the past few years, shown below. Each slide can be clicked to open it in a separate window.

        • Re: PCI Express 4.0 Standard Officially Released

          Something that's being overlooked is the emergence of the NVMe market. With PCIe 3.0 there aren't enough lanes to supply a complement of PCIe slots as well as NVMe slots unless you go HEDT with Threadripper. While NVMe is now relegated mostly to the high end, prices of some of the lower end NVMe drives with performance superior to SATA drives are coming down in price per GB to SATA levels. By the time 2020 comes around and PCIe 4.0 makes it onto the market, they may be at or near price parity, so boards with 3 or 4 NVMe slots and only 2 SATA ports may be the norm.