The unexpected display of Intel's future Purley platforms at Computex 2016 revealed that the LGA 3647 socket, which is already employed in socketed Xeon Phi Knights Landing implementations, is apparently pin-compatible with the new platform.
However, Intel does not comment on unreleased products, so verification at the time was impossible. However, the final key to the puzzle was laying right under our nose in the Noctua booth at Computex.
Noctua had a new prototype cooler on display that supports the next generation AMD Opteron platforms, and more importantly, Intel's new Socket P, which the sign indicated is for both Skylake-EP (Purley) and Xeon Phi (Knights Landing) platforms. The company also confirmed that Skylake-EP and Knights Landing would share the same socket.
The prototype cooler, which Noctua designed for 3U and 4U servers and features NF-A9 PWM and NF-F12 PWM fans, is scheduled for release in 2017.
Intel employs the LGA 2011-3 socket for the Broadwell-E platform and also utilizes it for the Grantley and Brickland platforms. Intel designed the Grantley platform for the E5 Broadwell-EP family, whereas the Brickland platform is for the E7 Broadwell-EX family.
In the past, Intel has leveraged the same 2011-3 (R3) socket for a wide range of platforms, but frankly, it is hard to imagine Intel employing the same massive LGA 3647 socket in client-oriented Skylake-E or Kaby Lake-E platforms. The Purley platform will employ on-die FPGA architectures, which has no practical use in the enthusiast segment.
The large array of 3,647 pins in the LGA 3647 socket provides expanded connections for many of the on-die additives that Intel reportedly plans for Skylake-EP, such as the 100 Gbps OmniPath connectivity and three UPI interconnects (ostensibly a faster, more scalable QPI replacement). Further, these features will not make sense on an enthusiast platform, which might make Intel's future plans for the HEDT CPUs all the more interesting.
We often find details of future products by closely observing the surrounding ecosystems, such as heatsinks and motherboard vendors, and the latest discovery confirms that Purley and Knights Landing platforms are pin compatible. We expect further details to emerge in the coming months as more vendors build out the supporting products.
Paul Alcorn is a Contributing Editor for Tom's Hardware. Follow him on Twitter and Google+.
More: What public disclosures has Intel made about Knights Landing? (intel.com)
I haven't heard of any other socket for the Extreme series, so I expect it'll be Socket P. In single-CPU Socket 2011 boards and CPUs, the QPI pins aren't connected. And the FPGA probably won't be included in all SKUs. So, yeah, it'll waste some board space and result in larger-than-necessary CPU packages, but the overhead probably isn't worth creating yet another socket just for the single-CPU extreme/workstation/server market.
Then again, Xeon D has its own socket (FCBGA1667), so maybe...