Skylake motherboards are a bag-o-shite!

Hardware Motherboards
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Well maybe hot air coming from the same source.

The 16 PCI-e 3.0 lanes, mostly used for PCI-e slots, are connected directly to the CPU, and they are cool.

The 20 "high-speed" PCI-e lanes made available by the chipset are a hoax. They are all connected to the PCH, which communicates with the CPU through DMI 3.0, which has a bandwidth of just 4 x PCI-e 3.0 lanes.
So we have 20 so-called "high-speed" lanes squeezed through a bottleneck of just 4 lanes to the CPU.

Adding to the problem are motherboard manufacturers connecting PCI-e slots and M.2 slots to the chipset's PCH instead of directly to the CPU.
Usually the 3rd and 4th PCI-e slot, and 1 to 3 M.2 PCI-e slots.

Two examples are the Gigabyte GA-Z170X-UD5 TH and the Asrock Fatal1ty Z170 Professional Gaming i7.

Gigabyte GA-Z170X-UD5 TH :

The 3rd PCI-e slot (x4) is connected to the PCH, not to the CPU.
It's also in contention for those 4 lanes with the M.2 connector. You can't use both at the same time. Using the M.2 connector disables the 3rd PCI-e slot.
You also can't use that 3rd PCI-e slot for SLI because the lanes must come from the CPU according to the SLI specs. (Not a great loss at x4 speed.)
But the big one. M.2 using those 4 lanes would max out the DMI 3.0 interface from the PCH to the CPU.

Further the 2 Thunderbolt 3 USB Type-C outputs are good for 40Gb/s each.
But 16 PCI-e 3.0 lanes from the CPU equal roughly 16 x 4Gb/s = 64Gb/s.
20 "high-speed" lanes from the PCH could [b]theoretically[/] equal 20 x 4Gb/s = 80 Gb/s. Hooray! \o/
Oh no! Those 20 lanes are pushed to the CPU through DMI 3.0 which has a bandwidth of just 4 X 4Gb/s = 16Gb/s.

What is going on here?

Also, on November 19th 2015, I asked Gigabyte (my favourite brand for motherboards and graphics cards) at their support website ( esupport.gigabyte.com ) for a recommendation for a good quality cable or adapter to connect one of the Thunderbolt USB Type-C ports to the DisplayPort port of an LG MU3197-B monitor.
Or to put up a pdf file for download with some recommendations (what type, adapter or cable, what quality)
There were a few responses. They claim to have bought their cable for testing from a blogspot.tw subdomain. Yeah right! Gigabyte shops at a subdomain of a free hosting service. Bottom line, I'm still waiting for a response.
I also hinted in that ticket that I was under the impression that they hadn't tested connecting one of the USB Type-C ports to the DisplayPort of a 4K monitor. To which they responded on Dec 1st with :
"Due to we do not know the market in Netherlands, but we will check our responsible team about our test device,
We will come back to you once we get a reply."

Well, I'm still waiting for that definitive response. 3 weeks and counting.

My gut feeling says that they just slapped the Thunderbolt ports on, ran some lab tests, but never connected a monitor to the 2 Thunderbolt ports.

Note to self : Do not become a Guinea Pig. Do not become a Guinea Pig. Do not become a Guinea Pig.

2 weeks ago a very popular YouTube reviewer about finding a cable/adapter for the Thunderbolt 3 over USB Type-C connector (on the new Dell 15" XPS Infinity) at about 10:17 of the video (starting from 9:49 in) : https://youtube.com/watch?v=evjevd8BaDE&t=9m49s
Seems that she also can't source a [b]problem free[/b ] cable or adapter.

(I can send/post a screenshot of the ticket. But they have also been good to me with beautiful hardware.)

Asrock Fatal1ty Z170 Professional Gaming i7 :

This motherboard had many overselling issues.
Singling out just one.

It has 3 M.2 connectors, between the PCI-e slots. All 3 are connected to the PCH which can only reach out to the CPU through 4 lanes. So 12 lanes squeezed through 4 lanes. 3 x 32Gb/s squeezed through a bottleneck of 1 x 32Gb/s. Let's hope that they do not encourage setting up a RAID array spanning 3 M.2 SSDs.

Yep! Also U.2.

I've given up on Skylake. Sticking to my current ancient boxes. Checking out Intel again in 12 months.

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so butt hurt...

anyway, the main problem you are seeing is limitation of Intel Chipset. The only thing that can be compared here is hacks those companies implement to configs they think are good.

Every single mobo is like that... and i mean it.

Still usb/thunderbolt is not made by default for displays... the mobo makers only test with supplied test software/hardware company making usb typ-c / thunderbolt 3 chipset... if its working or not... don't blame mobo makers... they have nothing to do with it.

3 Likes
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This ^^^^^^^^^^

It's the main reason I always try to stay a generation behind current hardware, yeah there are performance issues but only a limited amount of butt hurt from being a beta tester for hardware you paid for, I have one of the Fatality 990FX boards and I knew from the time I bought it I'd never be able to use the M.2 because of the other hardware I wanted to run, but still it would be nice to be able to use all the features a MB has to offer without trade offs, but that's not the way it works.

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Likewise, OP seems to expect Skylake (E3 ?) to have the same amount of lanes you'd see in high end 2011v3 (E5) Consumer or Enterprise hardware. AFAIK, looking back at the architecture of E3 chips you will quickly see that most don't have more than 20 PCIe lanes. Intel does this to save cost for people who don't need a lot of I/O lanes for their applications (ex: single card, embedded, NAS, home server etc..), If OP wants more I/O so they can have a 16x card with 3 M.2. in RAID, then they should have stuck with a Haswell-E board or waited until Skylake-E chips came out.

The lesson OP should learn from this is research and buy components to suit your applications. Don't get the newest and greatest if it isn't going to meet your requirements.

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Frankly this is a lot of bitching and moaning that all can be condensed to, 'I want all the stuff X99 provides but on the consumer chipset.' If you want all the things your complaining that Z170 doesn't have, Because it is the consumer chipset that is not supposed to be ran with all these features enabled at once, just get a 5930k and a X99 board. Your complaining that this platform doesn't have all the features you want, but you can totally just step up to the next platform up. If you want to run 3 Gfx cards, an M.2, and a Thunderbolt card, you should be spending X99 money and not Z170 money anyways. If 40 Pcie lanes isn't enough for you, then get dual socket 2011-v3 board with 80 Pcie lanes on it.

1 Like
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even the 2011 chips have their quirks. Haswell-E has plenty of shared lanes or turned off lanes if this or that is used...
same goes for Sandy-E and Ivy-E.

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https://semiaccurate.com/2015/08/05/intel-plays-press-skylake-stupidity/

talks about the PCI thing

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So we got AMD being lazzy or not willing to compete, Nvidia failing to put fast enough 0.5GBs on their graphics cards and Intel not talking about their new product.
I will start soldering on my own cpu, see you in 30 years.

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here's a start

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So much misunderstanding and Ostrich policy.

Most who posted in response to me completely misunderstood.

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not me tho right? im on team drmario

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The specs of Z170 and skylake cpu's, are plain and clear.
Intel mainstream cpu´s simply dont offer more then 16 physical pci-e lanes directly connected to the cpu.
Rest of the connectivity goes over the dmi bus.
I dont see why that would make Skylake mobo´s are a big of shit, like you are stating.
Its just a limmitation by intel basicly.

With Haswell this aint any diffrent.
The only diffrence with mainstream Haswell is that the dmi bus is only gen2 on Haswell.
So for that matter is Skylake Z170 an huge improvement over haswell.

If you need more physical lanes directly connected to the cpu.
then you simply need X99.

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I think I covered that in every video I did on skylake? DMI 2.0 was pretty darn turdy. I did some tests with that intel 750 on DMI 2.0 on haswell and it was LOLWTFBBQ bad.

If you are a feature-freak go X99.

Also, the asrock board with the 3x m.2 connectors was just fine using 3 slower m.2 drives all at once. I was pushing maybe 1.5-1.8 gigabytes/sec. Yes, it'll bottleneck if you get 3 samsung drives for sure. Even 1.5gbyte/sec is pushing it. The DMI 3.0 seems to be about just two devices talking to each other as fast as possible.. e.g. USB3 to M.2 or SATA Express to M.2 or USB3 but not more than that.

If you want a of peripherals, there is no substituting X99.

I see the DMI 3.0 x4 PCIe problem like the old "shared PCI" bus problems from waaaay back a long time ago. This was one reason dual slot systems were so amazing-- two PCI busses with a high-speed link on the northbridge or some such.

It seems reasonable for a consumer board. Skylake prices are too high right now b/c scarcity. X99 is rocks-solid and plenty expandable. ?

4 Likes
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I agree with this, if we talk from an i7-6700K standpoint.
6700K costs more then the 5820K in the US atleast.
That realy makes no sense in most cases.

15

Hearing issues with Skylake makes me want Zen more and more.

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What issues are you refering to?

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Stuff like lacking in thermal compound on the IHS making temps bad and you can't delid because the PCB is too thin and risk breaking it. Even if Skylake didn't have any of those problems, Skylake is still a disappointment. I think Intel reached an IPC Cap for silicon so, you don't really need a new CPU anymore unless you're on AMD or a Core 2 Quad.

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Well i dont realy think that the temps are that bad at Skylake.
Theoreticly it should be better then Haswell, since Skylake does not have a Fivr,
but thats ofc just theoreticly.

Anyway, i agree that in terms of raw cpu power, there is not much of an improvement since sandybridge.
However some added instructions like AVX2.0 since Haswell, is realy an improvement in some area´s.
Also the platfoms them selfs have been improved allot, especialy Skylake with the dmi 3.0 bus.
And its ofc realy nice that intel offers support for things like vt-d on their unlocked i5's / i7´s since Devils canyon.

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CPUs are at the point of smartphones. They perform the same give or take 1-4%. Everything that matters are features coming in with a massive premium.
Wasn´t Intel advertising with "Bringing DDR4 to the mainstream."? Well, said mainstream is so expensive nobody arround me except two colleagues care about it.
As the game industry realized how much more they could do when they would start using more cores, the core count race is back. Cooperative cores can perform very well compared to single cores in business tasks. Maybe we will bring "six-cores requiered" to the mainstream.
Intel got lazy. In fact they got lazy to a point where someone startet looking into it. But all they found on their hunt were bubbles. I do not know and do not want to know what Intel is planing but for now it looks like a gold rush before AMD comes back.

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With these prices I don't know why anyone would choose a 6700k over a 5820k... With the 5820k + MB being only $12 more than a 6700k + MB it seems like a no brainer; 6 real cores + HT and 28 real PCI-E lanes.

Wish these had been the prices last year when I built my 4690k rig...

1 Like