Review: Much-improved Iris GPU makes the Skylake NUC a major upgrade

Intel’s “Next Unit of Computing” (NUC) mini desktops started off as interesting curiosities, experiments to see just how much computer could fit in a desktop PC that you could hold in your hand. Each subsequent generation has refined the overall concept and added other niceties, making it more and more like a solid consumer-ready computer (albeit one that makes you provide your own RAM and SSD and OS).

We looked at Intel’s fourth-generation NUC based on its still-relatively-new Skylake processors. On the outside, less has changed than ever before—Intel has settled on a “look” for the NUC and it’s not messing with the design much. On the inside, you get enough cool upgrades that you can almost forgive Intel’s CPU performance for improving so little in the last three or four years.

Model breakdown

Specs at a glance: Intel NUC NUC6i5SYK (as reviewed)
OS	Windows 10 x64
CPU	1.8GHz Core i5-6260U (Turbo Boost up to 1.9GHz)
RAM	16GB 2133MHz DDR4 (supports up to 32GB)
GPU	Intel Iris 540 (integrated with 64MB eDRAM)
HDD	256GB Samsung SM951 PCIe SSD
Networking	867Mbps 802.11ac Wi-Fi, Bluetooth 4.2, Gigabit Ethernet
Ports	4x USB 3.0, 1x mini DisplayPort 1.2, 1x HDMI 1.4b, headphones, SD card slot
Size	4.53” x 4.37” x 1.26” (115 x 111 x 32mm)
Other perks	Kensington lock, swappable lids, IR receiver
Warranty	3 years
Price	~$400 (barebones), about $755 as configured

There are four Skylake NUCs as of this writing. Two include a Core i5-6260U with an Iris 540 integrated GPU, and two use a slower Core i3-6100U processor and a slower HD 520 GPU. Each processor comes in two cases: a taller one that makes room for a 2.5-inch hard drive or SSD, and a shorter one that doesn’t. Otherwise, all models share the same basic design, port layout, and other features.

Both CPUs are 15W models like the ones that you would find in most Ultrabooks and midrange laptops. All of our observations about the design and build will apply to all models, but the performance and power consumption numbers apply specifically to the Core i5 model.

Design and build

The NUC is and has always been a “PC Kit,” meaning you’ve either got to supply your own RAM, SSD, and operating system or buy it from a reseller who has already done that work for you. As was the case last year, these NUCs come with an embedded 802.11ac Wi-Fi and Bluetooth 4.1 combo adapter. This year, it's the Intel 8260. Buying a 16GB kit of DDR4 RAM adds somewhere between $70 and $80 to the $400-ish street price, a 256GB PCI Express SSD like Samsung's 950 Pro will run you around $180, and Windows costs $100 if you don't have a license sitting around already. Going with 8GB of RAM, a SATA SSD, and/or Linux can reduce the price of your add-ons quite a bit, so just buy what you need.

Accessing the innards of the NUC is easy. There are four large captive Phillips-head screws on the bottom. Loosen these and the bottom of the NUC comes right off, exposing the twin DDR4 RAM slots, the M.2 slot for the SSD, and (in the tall models) the bay and cable for the 2.5-inch drive.

Intel's CPU performance has increased pretty slowly so far this decade—it has focused much more on improving its integrated GPUs and reducing power usage—but in recent generations the company has tried to make up for it by offering improvements to overall system performance. In the NUC, one of these improvements is support for 2133MHz DDR4 RAM, which runs at a higher speed and consumes less power than the 1600 and 1866MHz DDR3 that the Broadwell NUC supported.

DDR4 RAM isn’t quite as plentiful as DDR3 just yet, but as of this writing DDR4 pricing is only a little higher for 8GB and 16GB kits. It’s actually considerably cheaper if you’re in the market for 32GB of RAM spread out across two 16GB sticks, a configuration this NUC explicitly supports (the old one topped out at 16GB).

The Broadwell NUC had an M.2 slot too—in fact you could just take your drive out of last year’s NUC and put it in this year’s without a problem. It’s a B- and M-keyed slot so it can accept both SATA and PCI Express-based SSDs, and Intel supports both two- and four-lane PCIe drives. The only addition in the Skylake generation is that the chipset includes PCI Express 3.0 lanes, which can supply roughly double the bandwidth of PCI Express 2.0.

Once you've assembled it and installed your operating system of choice (we're working with Windows, though Intel lists Ubuntu, Mint, Fedora, and OpenSUSE as explicitly supported Linux distros), the NUC is designed to connect to what you need and then get out of the way. Like the Broadwell NUC, you get a total of four USB 3.0 ports. Two are on the front and two are on the back, and the yellow one on the front can charge devices even if the NUC is off.

There’s also an IR receiver and headphone jack on the front next to the USB ports. On the back, there’s a gigabit Ethernet jack, a mini DisplayPort 1.2 port that can drive a 4K display over a single cable at 60Hz, and a full-size HDMI 1.4b port (replacing the irritating mini HDMI port on the back of older NUCs). New to the NUC this year is a full-size SD card slot on the left side, a nice benefit for people who work with photos or video. You don’t get as much connectivity as you might from a larger desktop board, but Intel does pretty well here—the only things that could reasonably be described as “missing” are Thunderbolt 3 and/or USB Type-C, features that are being withheld for the forthcoming high-end quad-core NUC.

The box itself remains small and unassuming. It’s an aluminum square with rounded corners and cutouts for airflow. Intel has moved the power/sleep light from the top of the box to the front, where it will be more easily visible, and it’s just a hair taller than the equivalent Broadwell NUC, but otherwise there are no major changes. The glossy (easily scratchable, as you can see in our photos) lid is still removable, and can be replaced with other lids to change the look of the NUC or to add features—lids can plug into a USB header on the motherboard to add NFC, wireless charging, and other features, and any lid that worked with the Broadwell NUC should continue to work with the Skylake NUC.

Power consumption and fan noise

Another neat benefit of the NUC relative to normal desktop computers is that they don’t use a ton of power. The Skylake NUC holds just about level with the Core i5 Broadwell NUC from last year, give or take a watt here and there, and it typically consumes well under 40W of power even for the most strenuous workloads. Compared to the Core i7 Broadwell NUC and its beefier 28W processor, it consumes much less power and as far as we can tell it never needs to throttle. As in past NUCs, the fan can spin up audibly when the box is working hard for long periods of time (playing a game, editing and transcoding video, anything that’s CPU and GPU intensive), but normally it’s a quiet whirr that you’ll have trouble hearing over ambient room noise.

This achievement is even more impressive when you consider that the Skylake Core i5 NUC is usually faster than the Core i7 version, sometimes by a significant margin.

Activity	Broadwell i5 NUC	Broadwell i7 NUC	Skylake i5 NUC
Off/Hibernated	0.5W	0.5W	0.4W
Sleep mode	1.0W	1.0W	1.1W
Idle at desktop (display off)	6.7W	9.0W	7.1W
Watching YouTube in Chrome	9.1W	11.8W	10.2W
Running GFXBench Manhattan benchmark (peak)	37.2W	51.1W	34.1W
Running Prime95 CPU torture test	31.8W	50.9W (peak), 42.4W (sustained)	31.0W