Differences from Coffee Lake to Kaby Lake

Physical Design: Pin Outs

The platform for the new Coffee Lake systems is going to look and feel very similar to the 6th and 7th Generation platform, with some minor differences, but this could lead to a lot of confusion.

Intel has made it very clear that Coffee Lake processors will work only in Z370 motherboards, and not in the previous generation Z270 motherboards. This despite the fact that both generations of boards share the same socket design due to how the pins are used. In Intel’s 8th Gen datasheet posted online, a full pin-out is provided, showing that there is indeed a difference between the new Coffee Lake processors and the older Kaby Lake processors, and what those specific differences are.

 
Coffee Lake (left), Kaby Lake (right) - not to scale
Image from David Schor, Wikichip

With the new CPUs, more pins are converted from RSVD (reserved) to VCC (power) and VSS (ground), specifically, there are 18 more power pins and 14 more ground pins, with a slight rearrangement in how the pins are provided. Most of the changes can be seen just above the central blank area to the left, where grey RSVD areas are now red.

In any regular generational change, the pin-out adjustment is to be expected. This is usually accompanied by a change in the socket, such as from one flavor of LGA115x to another flavor of LGA115x, in order to avoid any confusion as to what processors work in what motherboards. These sockets might have been physically similar, such as the socket 775 and socket 771 processors, but notched differently to avoid misplacing a CPU into the wrong socket. But this difference does not exist for Coffee Lake.

Physical Design: Notches

So the pin-outs for Coffee Lake and Kaby Lake are different, especially with the support for hex-core processors, but that is not a big story. What is a big story is as the physical socket being identical to the last platform: both use LGA1151. To compound the issue, both sets of processors have the same notches in the same places on their packages, making it very easy to place the wrong CPU in the wrong motherboard. Notches are typically used to physically restrict which processors go into which motherboards. Intel decided there was no need to differentiate this time around.

Whoever at Intel thought this was a good idea needs to reevaluate their decisions. If the new CPU was labelled as LGA1153, still had 1151 pins but slightly different notches, this wouldn’t be an issue because users would not be able to misplace (and potentially damage) their new CPUs by placing them in the wrong motherboards.

Integrated Graphics

Blowing up specialized sand aside, there is going to be a few differences in the capabilities of each platform. The new processors will support HDCP2.2 on both DisplayPort and HDMI, although an external LSPCon is still needed for HDMI 2.0.

The video outputs for Coffee Lake will be similar to that on Kaby Lake, with three display pipes supported for motherboard manufacturers to configure as needed.

The full decode/encode support is listed below.

Perhaps surprisingly, Intel did not explicitly mention the state of the integrated graphics in the new set of processors during our pre-briefing. This is odd, especially given the amount of time spent praising the virtues of previous generations of the graphics. Due to the early announcement of the processors last week, more details have emerged.

All the six processors being made available today will have Intel’s UHD Graphics 630. This is basically identical to the previous generation's HD Graphics 630, except the name is now UHD, which we suppose is for marketing purposes now that UHD content and displays are more ubiquitous when the naming first started. The other change is HDCP2.2 support.

We were told that there are performance improvements with the new graphics package, mainly from an updated driver stack but also increased frequencies. All the parts will have an idle frequency of 350 MHz, and boost up to the following frequencies:

Intel 8th Generation 'Coffee Lake' Desktop Processors
  i7-8700K i7-8700 i5-8600K i5-8400 i3-8350K i3-8100
Integrated Graphics GT2: 24 EUs GT2: 23 EUs
IGP Base Freq 350 MHz 350 MHz
IGP Turbo 1.20 GHz 1.20 GHz 1.15 GHz 1.05 GHz 1.15 GHz 1.10 GHz

In the case of the Core i7-8700K, this is a 50 MHz jump over the previous generation.

The Intel Z370 Chipset

From a high level, the Z370 chipset is identical to the Z270 chipset. The connectivity is the same, the number of supported PCIe 3.0 lanes is the same, the available bifurcation is the same, the controller support is the same: it is the same chipset under a new name, to help identify the new motherboards that support Intel’s 8th Generation processors compared to the previous chipset for the previous generation of processors.

From the chipset directly we get 20-24 PCIe 3.0 lanes, six SATA 6 Gbps ports with support for RAID 0/1/5/10, a total of 14 USB ports (either 2.0 or 3.0, up to a maximum of ten of USB 3.0), and support for network controllers, support for Thunderbolt 3, and support for Intel’s Optane memory as a boot drive. It’s critical that we say ‘support’ here, because the diagram above from Intel is misleading: Intel is not supporting Thunderbolt directly from the chipset, and motherboard manufacturers will have to include a Thunderbolt 3 controller in order to do so.

So on the face of it, the chipset is not too different. What will be different is on the motherboard-as-a-whole side.

Die Sizes and DRAM Compatibility Intel vs AMD: The Start of Core Wars
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  • mkaibear - Saturday, October 7, 2017 - link

    Well, I'd broadly agree with that!

    There are latency issues with that kind of approach but I'm sure they'd be solvable. It'll be interesting to see what happens with Intel's Mesh when it inevitably trickles down to the lower end / AMD's Infinity Fabric when they launch their APUs.
  • mapesdhs - Tuesday, October 10, 2017 - link

    Such an idea is kinda similar to SGI's shared memory designs. Problem is, scalable systems are expensive, and these days the issue of compatibility is so strong, making anything new and unique is very difficult, companies just don't want to try out anything different. SGI got burned with this re their VW line of PCs.
  • boeush - Saturday, October 7, 2017 - link

    I think it's a **VERY** safe bet that most systems selling with an i7 8700/k will also include some sort of a discrete GPU. It's almost unimaginable that anyone would buy/build a system with such a CPU but no better GPU than integrated graphics

    Which makes the iGPU a total waste of space and a piece of useless silicon that consumers are needlessly paying for (because every extra square inch of die area costs $$$).

    For high-end CPUs like the i7s, it would make much more sense to ditch the iGPU and instead spend that extra silicon to add an extra couple of cores, and a ton more cache. Then it would be a far better CPU for the same price.

    So I'm totally with the OP on this one.
  • mkaibear - Sunday, October 8, 2017 - link

    You need a better imagination!

    Of the many hundreds of computers I've bought or been responsible for speccing for corporate and educational entities, about half have been "performance" oriented (I'd always spec a decent i5 or i7 if there's a chance that someone might be doing something CPU limited - hardware is cheap but people are expensive...) Of those maybe 10% had a discrete GPU (the ones for games developers and the occasional higher-up's PC). All the rest didn't.

    From chatting to my fellow managers at other institutions this is basically true across the board. They're avidly waiting for the Ryzen APUs to be announced because it will allow them to actually have competition in the areas they need it!
  • boeush - Sunday, October 8, 2017 - link

    It's not surprising to see business customers largely not caring about graphics performance - or about the hit to CPU performance that results from splitting the TDP budget with the iGPU...

    In my experience, business IT people tend to be either penny-wise and pound-foolish, or obsessed with minimizing their departmental TCO while utterly ignoring company performance as a whole. If you could get a much better-performing CPU for the same money, and spend an extra $40 for a discrete GPU that matches or exceeds the iGPU's capabilities - would you care? Probably not. Then again, that's why you'd stick with an i5 - or a lower-grade i7. Save a hundred bucks on hardware per person per year; lose a few thousand over the same period in wasted time and decreased productivity... I've seen this sort of penny-pinching miscalculation too many times to count. (But yeah, it's much easier to quantify the tangible costs of hardware, than to assess/project the intangibles of sub-par performance...)

    But when it comes specifically to the high-end i7 range - these are CPUs targeted specifically at consumers, not businesses. Penny-pinching IT will go for i5s or lower-grade i7s; large-company IT will go for Xeons and skip the Core line altogether.

    Consumer builds with high-end i7s will always go with a discrete GPU (and often more than one at a time.)
  • mkaibear - Monday, October 9, 2017 - link

    That's just not true dude. There are a bunch of use cases which spec high end CPUs but don't need anything more than integrated graphics. In my last but-one place, for example, they were using a ridiculous Excel spreadsheet to handle the manufacturing and shipping orders which would bring anything less than an i7 with 16Gb of RAM to its knees. Didn't need anything better than integrated graphics but the CPU requirements were ridiculous.

    Similarly in a previous job the developers had ludicrous i7 machines with chunks of RAM but only using integrated graphics.

    Yes, some it managers are penny wise and pound foolish, but the decent ones who know what they're doing they spend the money on the right CPU for the job - and as I say a serious number of use cases don't need a discrete GPU.

    ...besides it's irrelevant because the integrated GPU has zero impact on performance for modern Intel chips, as I said the limit is thermal not package size.

    If Intel whack an extra 2 cores on and clock them at the same rate their power budget is going up by 33% minimum - so in exchange for dropping the integrated GPU you get a chip which can no longer be cooled by a standard air cooler and has to have something special on there, adding cost and complexity.

    Sticking with integrated GPUs is a no-brainer for Intel. It preserves their market share in that environment and has zero impact for the consumer, even gaming consumers.
  • boeush - Monday, October 9, 2017 - link

    Adding 2 cores to a 6-core CPU drives the power budget up by 33% if and **ONLY IF** all cores are actually getting fully utilized. If that is the case, then the extra performance from those extra 2 cores would be indeed actually needed! (at least on those occasions, and would be, therefore, sorely missed in a 6-core chip.). Otherwise, any extra cores would be mostly idle, not significantly impacting power utilization, cooling requirements, or maximum single-thread performance.

    Equally important to the number of cores is the amount of cache. Cache takes up a lot of space, doesn't generate all that much heat (compared to the actual CPU pipeline components), but can boost performance hugely, especially on some tasks that are memory-constrained. Having more L1/L2/L3 cache would provide a much better bang for the buck when you need the CPU grunt (and therefore a high-end i7), than the waste of an iGPU (eating up ~50% of die area) ever could.

    Again, when you're already spending top dollar on an i7 8700/k (presumable because you actually need high CPU performance), it makes little sense that you go, "well, I'd rather have **LOWER** CPU performance, than be forced to spend an extra $40 on a discrete GPU (that I could then reuse on subsequent system builds/upgrades for many years to come)"...
  • mkaibear - Tuesday, October 10, 2017 - link

    Again, that's not true. Adding 2 cores to a 6 core CPU means that unless you find some way to prevent your OS from scheduling threads on it then all those cores are going to end up used somewhat - which means that you have to plan for your worst case TDP not your best case TDP - which means you have to engineer a cooling solution which will work for the full 8 core CPU, increasing costs to the integrator and the end user. Why do you think Intel's worked so hard to keep the 6-core CPU within a few watts of the old 4-core CPU?

    In contrast an iGPU can be switched on or off and remain that way, the OS isn't going to assign cores to it and result in it suddenly dissipating more power.

    And again you're focussing on the extremely limited gamer side of things - in the real world you don't "reuse the graphics card for many years to come", you buy a machine which does what you need it to and what you project you'll need it to, then replace it at the end of whatever period you're amortising the purchase over. Adding a $40 GPU and paying the additional electricity costs to run that GPU over time means your TCO is significantly increased for zero benefits, except in a very small number of edge cases in which case you're probably better off just getting a HEDT system anyway.

    The argument about cache might be a better one to go down, but the amount of cache in desktop systems doesn't have as big an impact on normal workflow tasks as you might expect - otherwise we'd see greater segmentation in the marketplace anyway.

    In short, Intel introducing desktop processors without iGPUs makes no sense for them at all. It would benefit a small number of enthusiasts at a cost of winding up a large number of system integrators and OEMs, to say nothing of a huge stack of IT Managers across the industry who would suddenly have to start fitting and supporting discrete GPUs across their normal desktop systems. Just not a good idea, economically, statistically or in terms of customer service.
  • boeush - Tuesday, October 10, 2017 - link

    The TDP argument as you are trying to formulate it is just silly. Either the iGPU is going to be in fact used on a particular build, or it's going to be disabled in favor of headless operation or a discrete GPU. If the iGPU is disabled, then it is the very definition of all-around WASTE - a waste of performance potential for the money, conversely/accordingly a waste of money, and a waste in terms of manufacturing/materials efficiency. On the other hand, if the iGPU is enabled, it is actually more power-dense that the CPU cores - meaning you'll have to budget even more heavily for its heat and power dissipation, than you'd have for any extra CPU cores. So in either case, your argument makes no sense.

    Remember, we are talking about the high end of the Core line. If your build is power-constrained, then it is not high-performance and you have no business using a high-end i7 in it. Stick to i5/i3, or the mobile variants, in that case. Otherwise, all these CPUs come with a TDP. Whether the TDP is shared with an iGPU or wholly allocated to CPU is irrelevant: you still have to budget/design for the respective stated TDP.

    As far as "real-world", I've seen everything from companies throwing away perfectly good hardware after a year of use, to people scavenging parts from old boxes to jury-rig a new one in a pinch.

    And again, large companies with big IT organizations will tend to forego the Core line altogether, since the Xeons provide better TCO economy due to their exclusive RAS features. The top-end i7 really is not a standard 'business' CPU, and Intel really is making a mistake pushing it with the iGPU in tow. That's where they've left themselves wide-open to attack from AMD, and AMD has attacked them precisely along those lines (among others.)

    Lastly, don't confuse Intel's near-monopolistic market segmentation engineering with actual consumer demand distribution. Just because Intel has chosen to push an all-iGPU lineup at any price bracket short of exorbitant (i.e. barring the so-called "enthusiast" SKUs), doesn't mean the market isn't clamoring for a more rational and effective alternative.
  • mkaibear - Wednesday, October 11, 2017 - link

    Sheesh. Where to start?

    1) Yes, you're right, if the iGPU isn't being used then it will be disabled, and therefore you don't need to cool it. Conversely, if you have additional cores then your OS *will* use them, and therefore you *do* need to cool them.

    iGPU doesn't draw very much power at all. HD2000 drew 3W. The iGPU in the 7700K apparently draws 6W so I assume the 8700K with a virtually identical iGPU draws just as much (figures available via your friendly neighbourhood google). Claiming the iGPU has a higher power budget than the CPU cores is frankly ridiculous. (in fact it also draws less than .2W when it's shut down which means that having it in there is far outweighed by the additional thermal sink available, but anyway)

    2) Large companies with big IT organisations don't actually forego the Core line altogether and go with Xeons. They could if they wanted to, but in general they still use off-the shelf Dells and HPs for everything except extremely bespoke setups - because, as I previously mentioned, "hardware is cheap, people are expensive" - getting an IT department to build and maintain bespoke computers is hilariously expensive. No-one is arguing that for an enthusiast building their own computer that the option of the extra cores would be nice, but my point all along has been that Intel isn't going to risk sacrificing their huge market share in the biggest market to gain a slice of a much smaller market. That would be extremely bad business.

    3) The market isn't "clamoring for a more rational and effective alternative" because if it was then Ryzen would have flown off the shelves much faster than it did.

    Bottom line: business IT wants simple solutions, the fewer parts the better. iGPUs on everything fulfil far more needs than dGPUs for some and iGPUs for others. iGPUs make designing systems easier, they make swapouts easier, they make maintenance easier, they reduce TCO, they reduce RMAs and they just make IT staff's lives easier. I've run IT for a university, a school and a manufacturing company, and for each of them the number of computers which needed a fast CPU outweighed the number of computers which needed a dGPU by a factor of at least 10:1 - and the university I worked for had a world-leading art/media/design dept and a computer game design course which all had dGPUs. The average big business has even less use for dGPUs than the places I've worked.

    If you want to keep trying to argue this then can you please answer one simple question: why do you think it makes sense for Intel to prioritise a very small area in which they don't have much market share over a very large area in which they do? That seems the opposite of what a successful business should do.

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