High-end Intel Z170 motherboards duke it out

By Koh Wanzi - 20 Oct 2015

Introduction: What's new in Intel Z170?

New Chipset for a New Architecture

After the confusion that was Broadwell, Intel’s 14nm Skylake processors have finally dropped, and with it the new Intel Z170 chipset. The Intel Core i7-6700K and Core i5-6500K were released at Gamescom 2015, and Intel has since unveiled a whopping 48 sixth-generation parts for both desktop and mobile. After the drought, the rains have come indeed.

It looks like the Intel Core i7-6700K might be the long-awaited replacement to the Intel Core i7-4790K, the flagship Devil’s Canyon chip that is based on the Haswell microarchitecture first unveiled in 2013. However, the notable absence of a -90 in its naming scheme might indicate that higher-end parts are to follow later. Either way, it’s still the first performance-oriented desktop chip we’ve seen from Intel in a long while, with a Thermal Design Power of 91 watts.

The improvements brought about by the new Skylake microarchitecture can be distilled into three key areas – performance, power efficiency, and overclocking. It goes without saying that Skylake will be faster than its predecessors, but it will also offer better power efficiency thanks to changes like an integrated digital PLL (phase-locked loop) on the chip itself. Overclocking capabilities are also bolstered, and a wider range of BCLK values (base clock) is now available, which should provide enthusiasts with finer control over overclocking.

For the full details on the changes in Skylake’s microarchitecture, you can check out our article here.

But enough about the CPUs. Intel Z170 will use the new LGA 1151 socket for Skylake CPUs, and feature several improvements over Z97, most notably the support for DDR4 memory and expanded storage configurations available to you. Here’s a look at some of the key changes, before we proceed to take a look at some of the finest board specimens from the different manufacturers.

What’s new in Intel Z170


DDR4 arrives in the mainstream

A look at the DDR4 RAM slots on the ASUS Z170 Deluxe.

One of the major steps forward for Intel Z170 is the support for DDR4 memory, which marks the first time that DDR4 support will be available on a chipset other than the ultra-enthusiast Intel X99. In fact, Skylake motherboards will dispense with support for DDR3 RAM entirely, and will support either DDR4 or DDR3L RAM. But because the slots are different for each memory type, motherboards will only be able to support one of them, and the overwhelming majority of boards are going to opt for DDR4 support, which offers several advantages over older DDR3 modules.

For starters, DDR4 has a lower operating voltage of 1.2V, down from 1.5V on DDR3. This helps reduce power consumption. It also boasts higher data transfer rates – Skylake’s memory controller supports DDR4 2133MHz by default, as compared to DDR3 1600MHz on Haswell CPUs and Intel Z97. Furthermore, DDR4 enables higher memory densities, which means up to 16GB modules. Intel Z170 supports up to 64GB across four DIMMs, so you can really load up those RAM slots if you’re of the persuasion that there is no such thing as too much RAM.

To cap things off, manufacturers are also releasing kits at frequencies that DDR3 would be hard pressed to match. For instance, the new G.Skill Trident Z memory is available in kits clocked up to 4000MHz, nearly double that of the 2133MHz base specification.

These advantages aside, DDR4 does have a slightly higher CAS latency than DDR3 because of the higher memory frequencies. CAS latency is a measure of the time – or more precisely the number of clock cycles – taken by the memory to send data back to the processor when it receives a command. On the other hand, memory frequencies indicate how quickly the system can access data on the RAM. So while it might seem like higher CAS latencies would mean that DDR4 is slower, the outcome isn't always so straightforward because the two work together to influence memory performance.

Memory performance is determined more accurately by the actual latency time, or time to initiate a read, which is measured in nanoseconds (ns). Faster memory clock speeds result in shorter clock cycles between when the memory receives a command and when it actually responds, so even though the CAS latency goes up – more cycles – the actual latency time is only marginally increased, resulting in overall comparable performance. In fact, the higher clock speeds also enable faster transfers and higher bandwidth.

We've actually rounded up a handful of DDR4 kits for your consideration, and you can check them out here.


PCIe 3.0 support and high-speed storage

Intel Z170 block diagram. (Image Source: Intel)

With Z170, the processor is now connected to the chipset’s Platform Controller Hub (PCH) by the upgraded DMI 3.0 protocol. Compared to the DMI 2.0 used in Z97, DMI 3.0 features a speed boost from 5.0GT/s to 8.0 GT/s, which enables significant upgrades in chipset connectivity.

This explains why Intel Z170 is now able to support PCIe 3.0 on the chipset itself instead of PCIe 2.0 as on Z97. This results in a total of 20 PCIe 3.0 lanes being exposed through the chipset, compared to just eight PCIe 2.0 lanes on Z97. Skylake CPUs will continue to provide 16 PCIe 3.0 lanes for your graphics card, but additional PCIe 3.0 lanes on the chipset itself will now be available for use with PCIe 3.0 x4 storage devices.

These devices were of course supported on higher end Z97 motherboards, but it entailed drawing from the 16 PCIe 3.0 lanes provided by the CPU. So if you plugged in an M.2 PCIe 3.0 x4 SSD into a compatible board, the bandwidth sharing would force the PCIe 3.0 x16 slot to run in x8 mode.

WIth Z170, such bandwidth sharing is no longer necessary, and you’ll be able to utilize the maximum available bandwidth for both your graphics card and PCIe 3.0 x4 SSD. And as the number of such storage devices continues to grow, it’s important to finally see proper support for high-speed storage devices on Intel’s latest mainstream chipset.


More Connectivity Options

Image Source: AnandTech

Z170 also has a far more flexible selection of High-speed Input/Output (HSIO) ports than Z97. While the latter had 18 such ports that could switch between the PCIe lanes, USB 3.0 ports and SATA 6Gbps ports, Z170 now has 26 ports than can be implemented in a variety of ways.

This gives motherboard manufacturers greater ability to pick and choose what combination of connectivity options they’d like to offer. For instance, the new Intel Rapid Storage Technology (RST) allows Z170 to support up to three PCIe devices at one time, which means that M.2 and SATA Express devices can be installed in RAID arrays as long as they are connected via these HSIO lanes. In addition, this would allow motherboard manufacturers to implement up to three PCIe 3.0 x4 M.2 slots on their boards, complete with RAID support.

But even though Z170 officially supports 10 USB 3.0 ports (up from six on Z97), six SATA 6Gbps ports, and 20 PCIe 3.0 lanes, you can’t have everything all at once because the USB 3.0, SATA ports and gigabit LAN use these HSIO lanes as well. For example, populating both M.2 PCIe 3.0 x4 slots on the MSI Z170A Gaming M9 ACK will end up disabling two of the six SATA 6Gbps ports. This is because the SATA ports use a PCIe lane each, which overlaps with the lanes used for the M.2 slots.

Similarly, although Z170 can have up to 10 USB 3.0 ports, only six HSIO lanes are permanently configured as USB 3.0 connections. It is up to motherboard manufacturers to decide if they want to implement the other four, but that would mean taking up HSIO lanes seven to 10, which are also allocated to PCIe lanes one to four.

More expensive boards, but cooler CPUs

Speaking of expensive motherboards, the Gigabyte Z170X Gaming G1 will cost S$939. (Image Source: Gigabyte)

Finally, Intel Z170 will see motherboard manufacturers return to implementing voltage regulation on the board itself. This was the case prior to Haswell CPUs, but Z97 and Haswell/Broadwell processors saw Intel create a fully integrated voltage regulator (FIVR) on the CPU itself in order to reduce motherboard costs and power consumption. However, this also had a less desirable consequence in the form of additional heat output in overclocked CPUs. As a result, overclocking was limited by temperatures, and also by the varying quality of the FIVR on individual chips.

With Z170, Intel has handed the task of voltage regulation back to motherboard manufacturers, which could result in cooler processors, but slightly more pricy boards.

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