Intel is set to launch its 65W Skylake R-series CPUs this quarter in the form of the Core i5-6585R, the Core i5-6685R, and the Core i7-6785R. These new chips are all quad-core CPUs paired with Iris Pro graphics, which means we get three Skylake Gen9 GPU slices. Those three slices offer up 24 execution units (EUs) each, for a total of 72 EUs. That setup should make for a solid entry-level graphics solution. The highlight of these CPUs for enthusiasts may be the 128MB of eDRAM that Iris Pro brings with it, though. Intel's ARK indicates that these CPUs include improved turbo boost speeds and an L3 cache that matches that on board the Skylake K-series chips, an improvement over Broadwell R-series chips.
While the R-series Skylake chips are officially classified as desktop CPUs, they won't be socketable parts like the Core i7-5775C. That's in keeping with Intel's previous guidance that it won't be releasing socketable Skylake CPUs with Iris graphics. Since these aren't socketable chips, they're closer to mobile or embedded processors that use a ball-grid-array (BGA) motherboard connection. But even mobile and embedded isn't the right fit for the Skylake R-series CPUs, as their 65W TDP is a pretty hefty hurdle for mobile or embedded cooling solutions to clear. That leaves me wondering what products these CPUs are destined for.
From the thousand-foot level, low-TDP CPUs are suited towards mobile computing and high TDPs towards desktop PCs. Peering through the clouds at Skylake, we know that thin laptops are typically built with Intel's 15W Core i chips or even more power-sipping Core M chips. Thicker gaming or workstation notebooks are usually built with Intel's 45W CPUs in mind. I've compiled this table of Intel ARK data on a wide range of CPUs with Iris graphics so that we can discuss what a 65W Skylake R-series system might look like.
|Core i7-6650U||Core i7-6567U||Core i7-6770HQ||Core i5-6585R||Core i5-6685R||Core i7-6785R||Core i7-5775C|
|Base Clock (GHz)||2.2||3.3||2.6||2.8||3.2||3.3||3.3|
|Turbo Clock (GHz)||3.4||3.6||3.5||3.6||3.8||3.9||3.7|
|L3 Cache (MB)||4||4||6||6||6||8||6|
|GPU||Iris 540||Iris 550||Iris Pro 580||Iris Pro 580||Iris Pro 580||Iris Pro 580||Iris Pro 6200|
|GPU Base Clock (MHz)||300||300||350||350||350||350||300|
|GPU Max Clock (MHz)||1050||1100||950||
|Found in||Microsoft Surface Pro 4||Vaio Z flip||Intel Skull Canyon||N/A||N/A||N/A||Desktop PC|
At the low-end of the TDP scale, we find products such as the Core i7-6650U-powered Microsoft Surface Pro 4 and the Core i7-6560U-powered Dell XPS 13. Those 15W CPUs are a far cry from the 65W R-series. A real concern, as evidenced by posts on Reddit and Ultrabook Review, is that these devices are known to have issues with throttling due to insufficient cooling or aggressive thermal limits. That's because modern CPUs with integrated graphics often have to balance their thermal budgets between these resources. Those aggressive thermal constraints can sometimes be overcome with software such as TechPowerUp's ThrottleStop, though. My hope with 65W CPUs is that manufacturers will be aware of the thermal demands of the chip and provide sufficient cooling that won't hamper the R-series chips' performance.
The 28W Core i7-6567U is available in the likes of the Vaio Z flip. This CPU could easily have been omitted were it not for the fact that it supports the same number of threads and is clocked competively with the i5-6585R and i5-6685R. The i7-6567U's 3.3 GHz base and 3.6 GHz Turbo clocks compare well with the i5-6685R's 3.2 GHz base and 3.8 GHz turbo speeds. The caveats are that the i7-6567U has less L3 cache (4MB versus 6MB), a smaller 64MB eDRAM cache, and Hyper-Threading support compared to the dedicated quad-core hardware of the Core i5-6585R and Core i5-6685R.
Moving into the 45W TDP range, we have NUCs like Intel's Skull Canyon, powered by the Core i7-6770HQ. As the i7-6770HQ is the Iris variant of the i7-6700HQ, we can also find this level CPU performance in laptops like Dell's XPS 15. Those machines seem capable of entry-level gaming on their own, but they can't replace a midrange or high-end discrete GPU. Because of the thermal demands of a 65W chip, it's unlikely we'll see a Skylake-R chip in this product segment.
The most familiar 65W Iris CPU to our readers may be Intel's Core i7-5775C, which matches up well with the i7-6785R based on Intel's ARK specifications. From our i7-6700K review, we saw the i7-5775C was a surprise contender. That chip delivered impressive gaming benchmarks across the board, thanks to its 128MB of eDRAM. It's easy to imagine that the i7-6785R may deliver better frame-time performance than a Core i7-6700K thanks to its similar CPU architecture, clock speed, L3 cache, and even Iris GPU EUs (not that you'd use the IGP for demanding games). To be clear, eDRAM isn't the end-all, be-all of performance in my eyes, but it makes a strong case for the Skylake R-series CPUs as good foundations for a gaming platform.
Where does this leave the Skylake R-series CPUs? There's always the possibility of a high-end mobile workstation replacement to be powered by these chips. For example, an HP ZBook or Dell Precision mobile workstation would seem like good homes for one of one of these CPUs. Another possibility is a larger NUC-like system from Intel, Gigabyte, or Zotac that can handle the relatively high TDP of these chips. Gamers choosing one of these solutions could add a discrete GPU by taking advantage of an external GPU solution over Thunderbolt 3. Until such a system emerges, though, it's hard to judge what these CPUs might mean for the enthusiast.
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