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A new socket: LGA2011-v3
As you might expect given the VR integration and the shift to DDR4, Haswell-E adopts a new socket type that isn't compatible with prior chips. Intel calls it Socket 2011-v3. Although the pin config is different, the new socket looks a lot like the one it replaces. That's good news, since we're fans of the robust retention mechanism and physical design of LGA2011. Coolers made for LGA2011 sockets should work just fine with LGA2011-v3, too.

This socket is tightly flanked by DIMM slots. Cooler clearance around it will be an issue, which is one reason folks tend to choose water cooling for Core i7 Extreme systems. As you can see above, Corsair sensibly chose to equip its Vengeance LPX DIMMs with low-profile heat spreaders, which is the right way to do it, in my view.

The deal with DDR4 memory
This new platform requires DDR4 memory, of course. The modules have 288 pins and are notched differently along the bottom, so they're completely incompatible with DDR3. DDR3 has been with us for a long, long time, and the switch to a new memory type promises big benefits, at least eventually.


A DDR4 module (top) versus DDR3 (bottom)

One major plus is lower-power operation. Samsung says DDR4 modules require about 30-40% less power than even DDR3L DIMMs. Some of that gain comes from a lower 1.2V standard operating voltage, and the rest comes from a collection of design features expressly intended to improve power efficiency. For instance, DDR4's smaller-sized pages require less power to activate. All told, the savings should add up to about 2W per module. That's not really a big deal in the context of a high-end desktop, but it would be in a tablet or in a server crammed full of DIMMs.

Speaking of which, DDR4 is also primed to achieve higher bit densities than DDR3, and the spec includes native support for chip stacking. Samsung is already using through-silicon vias to stack four DDR4 chips on top of one another.

Another big perk of DDR4 is, of course, additional bandwidth. This new standard has been designed to reach higher transfer rates than DDR3. As with most new memory types, its potential may not be realized right away. DDR3 currently tops out at 2133MHz, more or less, and that's where DDR4 starts with Haswell-E. Thing is, memory makers are already working on DDR4 chips capable of 3200 MT/s operation.

Although the Core i7-5960X doesn't officially support RAM speeds above 2133 MT/s, the firmware on our Asus X99 Deluxe offers options as high as 4000 MT/s. Heck, the Corsair Vengeance LPX DIMMs we used for testing are rated for 2800 MT/s at 1.2V. Intel has even blessed an XMP (for eXtreme Memory Profile) 2.0 spec that will allow DDR4 DIMMs to auto-configure themselves at higher clocks on X99 motherboards.

So DDR4 looks to have plenty of headroom right out of the gate. The more difficult question is whether any common consumer applications will actually benefit from the additional bandwidth.

The X99 platform


Block diagram of the X99 chipset and platform. Source: Intel.

Few folks will question the wisdom of giving the X99 chipset more oomph. This new companion I/O chip is loaded to the gills, with 10 SATA 6Gbps ports and six USB 3.0 ports, which is enough not to be embarrassing like the X79. The X99 chip can also support M.2 and SATA Express-based storage, although you're surely better off hanging fast SSDs directly off of the CPU. What happens there will depend on the motherboard makers.

Mobo manufacturers also have the option of implementing Thunderbolt 2 on the X99 platform if they wish. Doing so will add some costs, as Thunderbolt tends to do, but the return will be an external I/O connection that's capable of 20 Gbps transfers. That's twice the rate of the original Thunderbolt and four times what USB 3.0 can sustain.

The possibilities for I/O configurations on X99 boards are incredibly complex given the number of ports, lanes, and slots available between the CPU and the X99 chipset. Geoff will be covering the particulars of various motherboards in his reviews, including today's look at the Asus X99 Deluxe. I'll leave most of the detail to him, but there is one caveat about the X99's setup I should note.

In the block diagram above, you can see the "DMI 2.0 x4" connection between the CPU and the X99. That's essentially a dedicated PCIe 2.0-style link from chip to chip—which means it has only 20 Gbps of raw, bidirectional bandwidth available to it. Behind this not-especially-fast interconnect are six USB 3.0 ports, eight USB 2.0 ports, eight PCIe 2.0 lanes, 10 SATA 6Gbps ports, and more. Do the math, and it's pretty abysmal. The X99 just can't support nearly the amount of concurrent I/O that its port payload suggests—not if those transfers are going to the CPU or memory. For most desktop users, this bottleneck probably won't become a problem too often, but it's still pretty far from ideal.