Z270 8x8x vs X99 or X299 16x16x performance for GTX 1080 Ti SLI

mouscous · Feb 20, 2017

I am planning a build for when the 1080 Ti comes out (planning on early April) and was originally going to go with the Z270 platform and the i7 7700k. I want to also do two 1080 Tis in SLI.

The problem is I have to run the cards in 8x8x on the 7700k and will have to go to X99 to run 16x16x SLI. There is a noticeable performance difference for GTX 1080s and Titan X Pascals, so I imagine there will be as well for the 1080 Tis.

See this article for Titan X Pascal results: https://www.pugetsystems.com/labs/articles/Titan-X-Performance-PCI-E-3-0-x8-vs-x16-851/

I also know the Intel X299 platform will be coming out possibly Q3 2017, but I do not want to wait that long.

My question is: should I be concerned running GTX 1080 Ti SLI at 8x8x with a 7700k on the Z270 platform instead of 16x16x on X99 or X299? I feel that GPUs have gotten to the point were PCIe 3.0 bandwidth matters..

Thanks in advance for the help.

Supahos · Feb 20, 2017

https://www.pugetsystems.com/labs/articles/Titan-X-Performance-PCI-E-3-0-x8-vs-x16-851/

8x is still perfectly fine

junkeymonkey · Feb 20, 2017

http://www.gamersnexus.net/guides/2488-pci-e-3-x8-vs-x16-performance-impact-on-gpus

https://www.pugetsystems.com/labs/articles/Titan-X-Performance-PCI-E-3-0-x8-vs-x16-851/

about all you got to go by is any test review on that and theres not many

sure don't seem worth the cost but there are some like z170 / z270 boards that has a plx chip on them ? for a example may come out a bit cheaper and still get 2 x16

4 x PCI Express 3.0 x16 Slots (PCIE1/PCIE2/PCIE4/PCIE5: single at x16 (PCIE1); dual at x16
http://www.asrock.com/mb/Intel/Z270%20SuperCarrier/index.asp#Specification

https://www.newegg.com/Product/Product.aspx?Item=N82E16813157753&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-PCPartPicker,%20LLC-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=

mouscous · Feb 20, 2017

junkeymonkey :

Thanks for the response.

You can run 2 PCIe x16 slots with Z270? Could you elaborate on this plx chip? Isn't running 2 PCIe x16 slots impossible with the i7 7700k if it only has 20 PCIe lanes?

junkeymonkey · Feb 21, 2017

How Does a PCI Express Switch (like the PEX 8747) Work

http://www.anandtech.com/show/6170/four-multigpu-z77-boards-from-280350-plx-pex-8747-featuring-gigabyte-asrock-ecs-and-evga

I will say I would prefer the x board and a cpu with the lanes for true slot speeds eather way intel sees you coming $$ wise ..

unlike AMD all theres run off the chipset not the cpu as intel and can offer 16x16 I think there chipset has like 42 lanes for everything

still with a ''X'' board like a X99 you still have that cpu limitation '' *If you install CPU with 28 lanes, PCIE1/PCIE3/PCIE5 will run at x16/x8/x4.''

''If M.2 PCI Express module is installed, PCIE5 slot will be disabled''

''To support 3-Way SLI™, please install the CPU with 40 lanes'' so right off 16+16 = 32 + any slot used like a M2 that's also tied to the cpu and not the chipset as well [check manual on pci slot configurations ] may not be so cut and dry as it appears

http://www.asrock.com/mb/Intel/X99%20Extreme4/?cat=Specifications

then this is where you see some ''X'' boards have a plx on them as well

''◾4-Way SLI™ & 4-Way CrossFireX™ (x16) supported by 2 embedded PLX 8747 bridges ''

http://www.asrock.com/mb/Intel/X99%20Extreme11/?cat=Specifications

no cpu lane footnotes as like the non plx extreme 4

and of course intel $ees you coming and priced accordingly what it comes down to is 8x8 is doing the job for 2 cards ''but '' if you add another device in a slot that's wired to the cpu lanes that may not hold and then your dropped to 8x4x4

some boards have the 2 pci-e lane dedicted to the 16 cpu lanes and a lot do not so adding a 3ed device may affect that

like my board

The three PCI Express 3.0 x16 slots are controlled by the CPU, with the first slot working at x16 when only one video card is installed, the first two working at x8 when two video cards are installed, and the first working at x8 and the other two working at x4 when three video cards are installed. and like most add M2 may disable a slot ..

then this board

The two PCI Express 3.0 x16 slots are controlled by the CPU, with the first slot working at x16 when only one video card is installed, and with both working at x8 when two video cards are installed.

with it regardless the 2 main gpu slots are allways x16 single or 8x8 dual

anyway you got to look over each board to see how all this is ''wired'' and that changes widely between boards form any brand .

can be a lot to have to look at and over

like here the 2 main gpu slots are dedicated to the cpu and all ways run at x16 single or 8x8 dual the rest is run through the chipset lanes

http://www.asrock.com/mb/Intel/Z270%20Extreme4/#Specification

[ ps , not trying to indorse asrock but its easy to find and grab info from them ]

Sam_269 · Jul 23, 2017

junkeymonkey :

How Does a PCI Express Switch (like the PEX 8747) Work

http://www.anandtech.com/show/6170/four-multigpu-z77-boards-from-280350-plx-pex-8747-featuring-gigabyte-asrock-ecs-and-evga

I will say I would prefer the x board and a cpu with the lanes for true slot speeds eather way intel sees you coming $$ wise ..

unlike AMD all theres run off the chipset not the cpu as intel and can offer 16x16 I think there chipset has like 42 lanes for everything

still with a ''X'' board like a X99 you still have that cpu limitation '' *If you install CPU with 28 lanes, PCIE1/PCIE3/PCIE5 will run at x16/x8/x4.''

''If M.2 PCI Express module is installed, PCIE5 slot will be disabled''

''To support 3-Way SLI™, please install the CPU with 40 lanes'' so right off 16+16 = 32 + any slot used like a M2 that's also tied to the cpu and not the chipset as well [check manual on pci slot configurations ] may not be so cut and dry as it appears

http://www.asrock.com/mb/Intel/X99%20Extreme4/?cat=Specifications

then this is where you see some ''X'' boards have a plx on them as well

''◾4-Way SLI™ & 4-Way CrossFireX™ (x16) supported by 2 embedded PLX 8747 bridges ''

http://www.asrock.com/mb/Intel/X99%20Extreme11/?cat=Specifications

no cpu lane footnotes as like the non plx extreme 4

and of course intel $ees you coming and priced accordingly what it comes down to is 8x8 is doing the job for 2 cards ''but '' if you add another device in a slot that's wired to the cpu lanes that may not hold and then your dropped to 8x4x4

some boards have the 2 pci-e lane dedicted to the 16 cpu lanes and a lot do not so adding a 3ed device may affect that

like my board

The three PCI Express 3.0 x16 slots are controlled by the CPU, with the first slot working at x16 when only one video card is installed, the first two working at x8 when two video cards are installed, and the first working at x8 and the other two working at x4 when three video cards are installed. and like most add M2 may disable a slot ..

then this board

The two PCI Express 3.0 x16 slots are controlled by the CPU, with the first slot working at x16 when only one video card is installed, and with both working at x8 when two video cards are installed.

with it regardless the 2 main gpu slots are allways x16 single or 8x8 dual

anyway you got to look over each board to see how all this is ''wired'' and that changes widely between boards form any brand .

can be a lot to have to look at and over

like here the 2 main gpu slots are dedicated to the cpu and all ways run at x16 single or 8x8 dual the rest is run through the chipset lanes

http://www.asrock.com/mb/Intel/Z270%20Extreme4/#Specification

[ ps , not trying to indorse asrock but its easy to find and grab info from them ]

That was a great answer. I am in the same situation as the OP. I have an ASUS z270E Gaming with a 7700K and two GTX 1080 in SLI with HB and an NVME M.2 drive. Now that the 7900x is available I am wondering if there is any gain (not considering the price)

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Z270 8x8x vs X99 or X299 16x16x performance for GTX 1080 Ti SLI

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