Motherboard PCIE Slots 1 and 3 (2 Way SLI) Urgent

[atos28]

Hi guys,

I just wanna know if i get a motherboard LGA 1150 socket with 3 PCIE x16 slots such as the MSI Gaming 5, 7 or Asrock Z97x killer or Gigabyte GA-Z97X-UD5H, will I be able to run my 2 GTX 980's in SLI with the 1st PCIE slot and 3rd PCIE slot (I want to do this for better cooling).

I have not been able to find a concrete answer to this and people from shops have had mixed opinions and thoughts. I need help on this ASAP because i am buying a motherboard in the next coming days.

Thanks

 

[i7Baby]

Yes - you can. eg MSI Gaming 5 - 3 x PCIe 3.0 x16 slots, (support x16, x8/x8, x8/x4/x4 modes)

and Multi-GPU: NVIDIA SLI & AMD CrossFire Support

Though I don't think nVidia likes their cards on x4 slots. So just a low end card.

 

[MarkW]

Make sure that any video cards you buy use no more than 2 slots wide cooling forms. There are a fair number of cooling solutions that exceed the 2 slot width.

 

[atos28]

Yes - you can. eg MSI Gaming 5 - 3 x PCIe 3.0 x16 slots, (support x16, x8/x8, x8/x4/x4 modes)

and Multi-GPU: NVIDIA SLI & AMD CrossFire Support

Though I don't think nVidia likes their cards on x4 slots. So just a low end card.

I dont understand what you mean exactly, if all 3 PCIE slots are 16x then why would the graphics card be 4x? wouldn't it be 8x/8x because it would only be using TWO (2) graphics cards and NOTHING else in the other slots (that means skipping the middle slot, empty and going straight to the 3rd slot)?

 

[MarkW]

Any Intel 1150 based CPU only offers 16 PCIe lanes. When only one video card is used, it gives all 16 lanes to slot 1. When you plug in the second video card into slot 3, both slot 1 and 3 split the 16 lanes between them. It works like this:

Single video card: 16x/0x/0x
Dual video cards: 8x/8x/0x
Triple video cards: 8x/4x/4x

Most motherboards follow the above rules. Nvidia requires 8 PCIe lanes for SLI. So a 3 card setup on an 1150 based motherboard cannot happen (see exception below).

A very small number of motherboards out there make use of Plex switches, and force PCIe lanes to be shared and offer more "lanes". Those motherboards are expensive due to the Plex Switches and the additional circuitry that is required to support them.

 

[atos28]

Make sure that any video cards you buy use no more than 2 slots wide cooling forms. There are a fair number of cooling solutions that exceed the 2 slot width.

Any Intel 1150 based CPU only offers 16 PCIe lanes. When only one video card is used, it gives all 16 lanes to slot 1. When you plug in the second video card into slot 3, both slot 1 and 3 split the 16 lanes between them. It works like this:

Single video card: 16x/0x/0x
Dual video cards: 8x/8x/0x
Triple video cards: 8x/4x/4x

Most motherboards follow the above rules. Nvidia requires 8 PCIe lanes for SLI. So a 3 card setup on an 1150 based motherboard cannot happen (see exception below).

A very small number of motherboards out there make use of Plex switches, and force PCIe lanes to be shared and offer more "lanes". Those motherboards are expensive due to the Plex Switches and the additional circuitry that is required to support them.

I understand if i was trying to do a 3 card setup but i'm saying that I am only doing a 2 (TWO) card setup,therefore shouldn't it be 8x/0x/8x? because i will be plugging in ONE (1) in the first slot and the other in the THIRD (3) slot? don't mind the caps I just wanna make sure everything is understood

 

[MarkW]

Slots 0, 2 , 4, 6 are normally much shorter slots. Some are 1x, some are 4x. Generally, the 16x slots, the ones the video cards can fit into, are every other slot, and on some motherboards they are every 3rd slot.

I use this next pic to show what I am talking about here... The two red slots are the ones the video cards would go into. If you look closely, you can see other short slots between those.

 

[atos28]

Slots 0, 2 , 4, 6 are normally much shorter slots. Some are 1x, some are 4x. Generally, the 16x slots, the ones the video cards can fit into, are every other slot, and on some motherboards they are every 3rd slot.

I dont think you understand me, I am saying that I DO NOT WANT anything else plugged in on any PCIE slots except the two GTX 980's (no wireless card, no sound card, absolutely nothing). So is it possible to run 2 WAY (just 2 NOT 3 or 4) sli in the first and third slots? they are only 2 cards so techinically it should be divided 8/0/8 (first 8 for the first slot and the last 8 for the third slot NOTHING in the middle)

 

[MarkW]

Of course. I like I said above, the video cards would go into the red slots in that image. Your motherboard may use colored slots or all black ones, but the same rules apply.

 

[atos28]

Of course. I like I said above, the video cards would go into the red slots in that image. Your motherboard may use colored slots or all black ones, but the same rules apply.

So i can use the top red slot and the bottom red slot (last one) with 2 gtx 980's and it will be 8x/0/8x on this motherboard below correct?

 

[MarkW]

Not according to specs AsRock has online. Remember this little chart I posted earlier...

Single video card: 16x/0x/0x
Dual video cards: 8x/8x/0x
Triple video cards: 8x/4x/4x

Ok, this is what AsRock lists:

- 3 x PCI Express 3.0 x16 Slots (PCIE2/PCIE4/PCIE6:
single at x16 (PCIE2);
dual at x8 (PCIE2) / x8 (PCIE4);
triple at x8 (PCIE2) / x4 (PCIE4) / x4 (PCIE6)

Looks like they follow my chart exactly. (Or I followed theirs).

 

[atos28]

Not according to specs AsRock has online. Remember this little chart I posted earlier...

Single video card: 16x/0x/0x
Dual video cards: 8x/8x/0x
Triple video cards: 8x/4x/4x

Ok, this is what AsRock lists:

- 3 x PCI Express 3.0 x16 Slots (PCIE2/PCIE4/PCIE6:
single at x16 (PCIE2);
dual at x8 (PCIE2) / x8 (PCIE4);
triple at x8 (PCIE2) / x4 (PCIE4) / x4 (PCIE6)

Looks like they follow my chart exactly. (Or I followed theirs).

isn't that only if you use ALL three of the pcie 16 slots? in my case i won't be using ALL of them I will only be using the First and Third slots. Thats what i'm trying to get at here.

 

[Wolfshadw]

What PCI-E slots you use for SLI is completely dictated by the motherboard manufacturer. You do not get to choose what slots you can use. Some motherboards may use the x8/x8/x0 configuration as MarkW suggests. Others may use the x8/x0/x8 as you want. It's completely motherboard dependent. You'll have to check the manual of each board to find out which uses which.

-Wolf sends

 

[MarkW]

MSI 5 shows PCI-E Gen Gen3 (16,0,0), (8,8,0), (8,4,4)
MSI 7 shows PCI-E Gen Gen3 (16,0,0), (8,8,0), (8,4,4)

Gigabyte GA-Z97X-UD5H shows:

1 x PCI Express x16 slot, running at x4 (PCIEX4)
* The PCIEX4 slot shares bandwidth with the PCIEX8 and PCIEX16 slots. When the PCIEX4 slot is populated, the PCIEX16 slot will operate at up to x8 mode and the PCIEX8 will operate at up to x4 mode.
* When installing a x8 or above card in the PCIEX4 slot, make sure to set PCIE Slot Configuration in BIOS Setup to x4. (Refer to Chapter 2, "BIOS Setup," "Peripherals," for more information.)
(The PCIEX16, PCIEX8 and PCIEX4 slots conform to PCI Express 3.0 standard.)

So all four of these motherboards follow my chart.

 

[MarkW]

As wolf says, we do not get to choose which slots. They are set by the motherboard manufacturer. And all 4 of these motherboards follow the standard chart that I have posted twice now.

The FIRST 16x slot is wired for 16x or 8x electronically.
The SECOND 16x slot is wired for 8x or 4x electronically.
The THIRD 16x slot is hardwired at 4x electronically.

 

[atos28]

As wolf says, we do not get to choose which slots. They are set by the motherboard manufacturer. And all 4 of these motherboards follow the standard chart that I have posted twice now.

The FIRST 16x slot is wired for 16x or 8x electronically.
The SECOND 16x slot is wired for 8x or 4x electronically.
The THIRD 16x slot is hardwired at 4x electronically.

ok now it makes sense, which motherboard can i do 8x/0x/8x with then?

 

[Wolfshadw]

As wolf says, we do not get to choose which slots. They are set by the motherboard manufacturer. And all 4 of these motherboards follow the standard chart that I have posted twice now.

The FIRST 16x slot is wired for 16x or 8x electronically.
The SECOND 16x slot is wired for 8x or 4x electronically.
The THIRD 16x slot is hardwired at 4x electronically.

ok now it makes sense, which motherboard can i do 8x/0x/8x with then?

You'll have to check the manual of each board to find out which uses which.

-Wolf sends

 

[i7Baby]

ASRock Z97 Extreme 11 - http://www.asrock.com/mb/Intel/Z97%20Extreme9/?cat=Specifications

Has extra pcie lanes with PLX PEX 8747 embedded chip. Otherwise, you only get 16. Otherwise, for Z97 3 slots it invariably runs at x8/x4/x4

 

[MarkW]

He only wants to use 2 cards, but he wants to use slots 1 and 4 instead of slots 1 and 3. For cooling reasons. He started another thread, and we've located a couple of motherboards that are setup that way for him.

 

[i7Baby]

What other thread?