The Coffee Lake Platform

8th Gen Coffee Lake series processors

During Computex 2017 last year Intel announced Kaby Lake-X and Skylake-X processors shortly followed by Coffee Lake announcements. Coffee Lake (8th gen) six-core processors are based on the LGA1151 socket but will require a new motherboard chipset. They have a TDP of either 65 or 95W. There will be several 6-core models with HT (12MB L3), and a handful without HT (9MB L3). The four core models (8MB L3) will not get hyper-threading.
 

 
Coffee Lake is based on a 14nm fabrication node with desktop versions in 4-core and 6-core models. These parts are tied to the B360, H370 and Z370 chipsets and, you guessed it, will require a new motherboard. Intel will release K models (unlocked) in the Coffee Lake generation.

Small architecture changes

The new Coffee Lake series processors share design elements found in the Kaby Lake and Skylake architecture that you know from the socket 1151 parts, but then scaled upwards to 6-cores. The processor series is fabbed at 14nm. Intel claims IPC has been improved meaning the number of instructions per clock-cycle has been improved. Our tests show that is not true. More on that later in the benchmarks though. Intel processor caches then, for Coffee Lake the L2 cache is 256 kB per core. The L3 cache is 12MB for the 6 cores enabled part and 9 MB for the models that have Hyperthreading disabled. Intel thus tweaked L2 and L3 caches based on SMT. With the new processors, you will also see two Turbo modes dubbed 2.0 and 3.0. We’ll keep it simple, but basically, with Turbo mode 3.0 one thread will clock higher whereas you use more than 1 thread, the Turbo mode 2 will kick in at a lower frequency on all cores and threads. If you already purchased a Z270 motherboard with the LGA 1151 socket you cannot re-use it with the 8th Gen Six-core processors. Despite using the same socket you will need to purchase a Z370 motherboard. This chipset will be called Z370 (Union Point platform), it will offer dual-channel memory for Coffee Lake processors (Intel rated up-to 2667 MHz). In the end that entails a four to six-core Coffee lake processor core line-up. There are some changes that you will need to be aware of. First off the DMI interface (the IO interconnect in-between the processor and chipset) is getting more bandwidth, roughly 4 GB/s. That means you’ll have 16x Gen 3 PCIe lanes on the processor which has another 4 for the DMI interface to the chipset. The Z370 chipset has high-speed I/O lanes with port flexibility with up to 24 PCIe 3.0 lanes from the chipset for connections in the IO like SATA, M.2, USB and so on-wards. As of 2017, Intel still did not embed USB 3.1 Gen 2 (10 Gbps)  into the processor but does offer 10x USB 3.1 Gen1 (5 Gbps) through the chipset.

The Processor and PCI-Express

• Coffee Lake Quad and Six core procs get 16 PCI-Express Lanes 3.0
• Kaby Lake-X Quad core procs get 16 PCI-Express Lanes 3.0
• Skylake-X six and eight core procs get 28 PCI-Express Lanes 3.0
• Skylake-X ten core procs get 44 PCI-Express Lanes 3.0

The Coffee Lake procs will support dual-channel DDR4 and 16 PCIe 3.0 Lanes. That means in the year 2018, with this Core i7 series processor, you still cannot get full x16 each with two graphics cards. The new platform also offers support for Intel Optane. The chipset will add additional PCI-e lanes for your storage connectivity. In-between the processor and the chipset is an updated DMI (revision 3.0) link (equivalent to a full PCIe 3.0 x4 link). 

The H370 Chipset

As the name implies, the Intel H370 is installed on this motherboard. Since there are no major changes, as such the specifications should not be all that different from Z370. In addition to 20 PCI Express lanes from the chipset, motherboards using this chipset can also offer up to 14 USB USB ports. To compare, the Z370 chipset adds up-to another 24 PCIe Lanes. There are also six SATA ports and an integrated Gigabit Ethernet. In addition to the LGA1151 for the Coffee Lake S processor, the motherboard offers four DIMM slots for DDR4 memory supporting 64GB in total, limited at 2667 MHz. Most boards will have two PCI Express x16 expansion slots, the second slot, however, provides only four lanes. 

As stated, the H370 chipset is a more cut-down version of Z370. Your main restrictions are:

• Just one full x16 PCIe Gen 3 link for dedicated graphics
• No overclocking capabilities at BIOS level
• Memory support is maxed at 2667 MHz (no OC mode or XMP will go higher).