Review: Intel Core i7-5960X (22nm Haswell)

X99 chipset and DDR4 memory

New processors usually grab all the release limelight, relegating the supporting core logic and memory to mere footnotes. This time, a brand-new chipset and DDR4 memory are equal partners in the platform.

Intel jumps from X79 to X99 in one fell swoop. The evolution has been a long time in coming, almost three years in fact, underscoring the lack of progress at the high-end consumer market; Intel's focus has been elsewhere, divided between datacentre and mobile products.

Here's a high-level overview of the chipset. As the name connotes, the LGA 2011-v3 socket is based on the LGA 2011 present on X79 but, and it really is worth repeating, is not compatible: X79 processors will not work in the new X99 motherboard, or vice versa. Why is this the case? Because the two generations of processors have different memory controllers, connecting with either DDR4 (X99) or DDR3 (X79) - there's no provision for a hybrid controller that can work for both boards.

Chipset-specific processors are notched in different ways to avoid confusion, but doubtless some will still arise as users look to put LGA 2011 chips into the wrong sockets. That said, we're glad that Intel didn't change the general socket; such a move would have proved irksome for cooler manufacturers who have an established range of air- and liquid-coolers in their premium arsenal.

DDR4 Memory - The Big Thing

DDR4 is best described as an evolution to incumbent DDR3. Key improvements are easiest to explain in table form.

DDR4 provides greater densities and therefore higher capacities than available from DDR3. Accompanying higher speeds is lower voltage, rated at 1.2V for standard modules and 1.05V for the most energy efficient. Based on the same manufacturing process measured consumption is 37 per cent lower than even DDR3L, according to Samsung. More important in the datacentre environment where every watt counts, reduced voltages, from a consumer perspective, should pave the way for reasonable overclocking.

The new memory standard achieves this drop in voltage by using techniques such as data-bus inversion, where algorithms reduce the amount of data that's transmitted by minimising the throughput of binary zeros. Should zero bits be the majority in a byte, data is inverted to save power. Put simply, less data is written than would otherwise be the case. The same technique is adopted in GDDR4 memory, by the way.

There are other architectural benefits aimed at the server market, including improved reliability, availability and serviceability (RAS). These take the form of CRC checking for errors, on-chip parity detection ensuring integrity of the command and address transfers, and per-module addressability.

But while DDR4 gives on a couple of fronts, it takes on another. A pursuit of higher speeds has the knock-on effect of increasing latencies. A raft of new DDR4 memory is coming to market, typically equipped with 15-15-15-38 latencies (or worse), meaning performance may suffer if the application demands very frequent accesses to system RAM. We'll examine such effects in standalone DDR4 reviews.

DDR4 memory is designed to scale from 2,133MHz to, we imagine, over 4,000MHz in time. There's always performance overlap between extant and new memories, more so at the time of launch, but Intel takes advantage of DDR4's increased bandwidth by equipping the trio of processors with quad-channel memory operating at a JEDEC 2,133MHz, up from a supported DDR3 1,866MHz on the Core i7-4xxx series, representing a near-15 per cent increase in potential bandwidth. Rival AMD is set to introduce DDR4 support with the ARM-based Hierofalcon sytem-on-chip processor next year.

And we can't bypass this section without talking about the ugly spectre that is price. Any new technology is limited in production and doesn't benefit from the economies of scale available to the incumbent. A 16GB (4x4GB) pack of DDR3-2,133 memory is available from around £130. This price increases to £170-plus for DDR4 of the same speed, thus pushing up platform costs accordingly.

The Other Stuff

Yet other than support for DDR4 memory, coming from the processor, X99 resembles X79's platform controller hub to a large degree. Intel adds four more SATA ports, all of the SATA 6Gbps variety, taking the total to 10. There's also provision for ThunderBolt 2 by having the PCIe hooks in place to take advantage of the high-speed interface.

Note the potential five-way x8 setup for graphics when using the two 40-lane HSW-E processors? Four is normal, so the fifth can be introduced by the motherboard manufacturer by using additional clock generators. Expect more workstation-specific boards to carry this feature.

It takes industry inertia for a standard to become commonplace. DDR4 is getting a helping hand by featuring on the fastest consumer platform to date, X99, and it's the main reason why the HSW-E processors need a revised motherboard featuring DDR4 slots. Expect entry-level X99 boards to feature four DIMM slots, two on each side, and premium models using eight, just as we see on X79.