Why you can trust Tom's Hardware Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.
The Lewisburg Chipset
Lewisburg Platform Controller Hub
The C620-series "Lewisburg" chipset replaces Intel's previous-gen C610-series "Wellsburg" PCH. Lewisburg adds several improvements, such as four additional SATA 6Gb/s and USB 3.0 ports. It features a DMI 3.0 interface, which is similar to a PCIe link between the processor and chipset. That's a nice doubling of throughput compared to C610's 2 GB/s DMI 2.0. The chipset also adds 12 additional PCIe 3.0 lanes and supports up to 25 HSIO (High Speed I/O) lanes.
A new CPU uplink option can provide eight and/or 16 PCIe lanes directly to the processor (separate from DMI).
Perhaps most important, Intel now has chipset options with a built-in X722 Ethernet controller that provides up to 4x10Gb/1Gb ports supporting iWARP RDMA and network virtualization offloads. There are also QuickAssist hardware offload accelerators that augment cryptography and compression/decompression performance. Notably, these additions don't consume DMI bandwidth. Instead, they utilize the CPU uplink to populate lanes connected directly to the processor. The x8 and x16 uplink options support a number of routing schemes, as outlined in the Lewisburg Deployment Configurations slide.
Vendors can configure a maximum of one PCH per CPU socket, but rarely extend beyond four per motherboard (even in eight-socket systems). Multiple PCHs increase I/O and accelerator capabilities and also allow the system to survive a chipset failure via failover.
There are several 14nm chipset options that range from a 15W TDP to 26W. Interestingly, the LBG-L and LBG-T hubs offer the same features, only one has a lower TDP. We suspect these power-optimized PCHs are manufactured using a 14nm+ process. We do know they cost more.
Integrated 10Gb Ethernet will likely enjoy quite a bit of support from enterprise customers. Intel claims the PCH-based approach results in 25% less power consumption than PCIe add-in cards. iWARP RDMA support, which bypasses the OS and kernel to reduce CPU utilization and network latency, is an enticing addition. Notably, Omni-Path uses RDMA, so it fits into the Intel's comprehensive networking approach.
MORE: Best CPUs
MORE: Intel & AMD Processor Hierarchy
MORE: All CPU Content
