The Intel 6th Gen Skylake Review: Core i7-6700K and i5-6600K Tested
by Ian Cutress on August 5, 2015 8:00 AM ESTSkylake's iGPU: Intel Gen9
Both the Skylake processors here use Intel’s HD 530 graphics solution. When I first heard the name, alarm bells went off in my head with questions: why is the name different, has the architecture changed, and what does this mean fundamentally?
Not coming up with many details, we did the obvious thing – check what information comes directly out of the processor. Querying HD 530 via Intel's OpenCL driver reports a 24 EU design running at 1150 MHz. This is different than what GPU-Z indicates, which points to a 48 EU design instead, although GPU-Z is not often correct on newer graphics modules before launch day. We can confirm that this is a 24 EU design, and this most likely follows on from Intel’s 8th Generation graphics in the sense that we have a base GT2 design featuring three sub-slices of 8 EUs each.
As far as we can tell, Intel calls the HD 530 graphics part of its 9th Generation (i.e. Gen9). We have been told directly by Intel that they have changed their graphics naming scheme from a four digit (e.g. HD4600) to a three digit (HD 530) arrangement in order "to minimize confusion" (direct quote). Personally we find that it adds more confusion, because the HD 4600 naming is not directly linked to the HD 530 naming. While you could argue that 5 is more than 4, but we already have HD 5200, HD 5500, Iris 6100 and others. So which is better, HD 530 or HD 5200? At this point it will already create a miasma of uncertainty, probably exaggerated until we get a definite explanation of the stack nomenclature.
Naming aside, Generation 9 graphics comes with some interesting enhancements. The slice and un-slice now have individual power and clock domains, allowing for a more efficient use of resources depending on the load (e.g. some un-slice not needed for some compute tasks). This lets the iGPU better balance power usage between fixed-function operation and programmable shaders.
Generation 9 will support a feature called Multi Plane Overlay, which is a similar feature to AMD’s video playback path adjustments in Carrizo. The principle here is that when a 3D engine has to perform certain operations to an image (blend, resize, scale), the data has to travel from the processor into DRAM then to the GPU to be worked on, then back out to DRAM before it hits the display controller, a small but potentially inefficient operation in mobile environments. What Multi Plane Overlay does is add fixed function hardware to the display controller to perform this without ever hitting the GPU, minimizing power consumption from the GPU and taking out a good portion of DRAM data transfers. This comes at a slight hit for die area overall due to the added fixed function units.
As shown above, this feature will be supported on Win 8.1 with Skylake’s integrated graphics. That being said, not all imaging can be moved in this way, but where possible the data will take the shorter path.
To go along with the reduced memory transfer, Gen9 has support for memory color stream compression. We have seen this technology come into play for other GPUs, where by virtue of fixed function hardware and lossless algorithms this means that smaller quantities of image and texture data is transferred around the system, again saving power and reducing bandwidth constraints. The memory compression is also used with a scalar and format conversion pipe to reduce the encoding pressure on the execution units, reducing power further.
Adding into the mix, we have learned that Gen9 includes a feature called the ‘Camera Pipe’ for quick standard adjustments to images via hardware acceleration. This adjusts the programmable shaders to work in tandem for specific DX11 extensions on common image manipulation processes beyond resize/scale. The Camera Pipe is teamed with SDKs to help developers connect into optimized imaging APIs.
Media Encoding & Decoding
In the world of encode/decode, we get the following:
Whereas Broadwell implemented HEVC decoding in a "hybrid" fashion using a combination of CPU resources, GPU shaders, and existing GPU video decode blocks, Skylake gets a full, low power fixed function HEVC decoder. For desktop users this shouldn't impact things by too much - maybe improve compatibility a tad - but for mobile platforms this should significantly cut down on the amount of power consumed by HEVC decoding and increase the size and bitrate that the CPU can decode. Going hand-in-hand with HEVC decoding, HEVC encoding is now also an option with Intel's QuickSync encoder, allowing for quicker HEVC transcoding, or more likely real-time HEVC uses such as video conferencing.
Intel is also hedging their bets on HEVC by also implementing a degree of VP9 support on Skylake. VP9 is Google's HEVC alternative codec, with the company pushing it as a royalty-free option. Intel calls VP9 support on Skylake "partial" for both encoding and decoding, indicating that VP9 is likely being handled in a hybrid manner similar to how HEVC was handled on Broadwell.
Finally, JPEG encoding is new for Skylake and set to support images up to 16K*16K.
Video Support
The analog (VGA) video connector has now been completely removed from the CPU/chipset combination, meaning that any VGA/D-Sub video connection has to be provided via an active digital/analog converter chip. This has been a long time coming, and is part of a previous committment made by Intel several years ago to remove VGA by 2015. Removing analog display functionality will mean added cost for legacy support in order to drive analog displays. Arguably this doesn’t mean much for Z170 as the high end platform is typically used with a discrete graphics card that has HDMI or DisplayPort, but we will see motherboards with VGA equipped in order to satisfy some regional markets with specific requirements.
HDMI 2.0 is not supported by default, and only the following resolutions are possible on the three digital display controllers:
A DP to HDMI 2.0 converter, specifically an LS-Pcon, is required to do the adjustments, be it on the motherboard itself or as an external adapter. We suspect that there will not be many takers buying a controller to do this, given the capabilities and added benefits listed by the Alpine Ridge controller.
477 Comments
View All Comments
taltamir - Friday, October 23, 2015 - link
Recognizing reality as it is, and being willing to admit that AMD is a joke, does not make someone an intel fanboy nor does it mean they want intel to win and AMD to fold.Samus - Wednesday, August 5, 2015 - link
This launch and the performance of skylake over haswell/broadwell is entirely unexpected because it is wholly unnecessary. The ipc improvement is upward of 10% in some cases, when normally it has been 4-6% in the past. It's amazing that the ipc improvement over nehalem is almost 50% while using nearly half the power. They are finally progressing after dogging along since sandybridgeptmmac - Saturday, August 8, 2015 - link
Intel has been turning a double decked supertanker to catch mobile chips on dozens of smaller platforms. Notably Apple is riding on a trialled super yacht and is leading the pack. The real,race going on right now is who will build the first photonics based chip and actually make money selling it. Intel is in that race, but we don't really have much data as to who will take the lead there. The real race is heading towards where the puck will be in 10 years. This is like watching Americas cup in the 50's. It is not important to the average person.Jaybus - Monday, August 10, 2015 - link
Expect hybrid chips first. These will have photonic i/o with electronic cores. This will allow an inter-chip [serial] bus at core-clock speeds, drastically reducing the need for on-chip caching and replacing 64 (or more) traces from CPU to DRAM with a single optical trace. L3 (maybe L2) could likely be eliminated, freeing up real estate and reducing power. Essentially, it allows using DRAM modules, peripheral chips, and even GPUs and other CPUs as if they were all on-chip. Actual photonic cores would come later, perhaps much later.CaedenV - Wednesday, August 5, 2015 - link
And we would all buy that processor rather than eternally waiting in purgatory. I really hope AMD puts out something amazing, even if I am not going to buy it.TheGladiator2212 - Friday, October 16, 2020 - link
Yup...This comment aged badly
Mariosti - Friday, September 10, 2021 - link
Well, this comment didn't age well.prisonerX - Thursday, August 6, 2015 - link
I think the funniest thing is how people bag AMD and praise Intel while paying through the nose for CPUs that are marginally faster (or marginally slower) than last generation.It's especially funny since Intel is selling its hottest chips (TDP wise, compared to other CPUs it makes) to the "mainstream" while wasting a huge % of the die on a useless integrated GPU that no-one who is willing to pay actually uses.
I always buy AMD because I support competition, it gives me much better value for my money, provides more balanced and batter matched performance and because I'm not a child I have no need for bragging rights about the singe threaded performance of my CPU that I don't need.
D. Lister - Thursday, August 6, 2015 - link
"I always buy AMD because I support competition, it gives me much better value for my money, provides more balanced and batter matched performance and because I'm not a child I have no need for bragging rights about the singe threaded performance of my CPU that I don't need."That's right... children brag about single-thread performance (was there anyone in this section actually doing that though?). Adults, on the other hand apparently, brag about several things simultaneously, like the better performance per dollar of their purchase, and having a superior sense of maturity, morality, economics and technology.
You sir, are duly nominated for the AnandTech comment section's esteemed "Irony of The Month" award for August '15... bravo!
Eugene86 - Thursday, August 6, 2015 - link
Well he's gotta justify that purchase decision to himself somehow...