Adding PCIe x1 when all lanes are in use

Kezekan

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Dec 9, 2014
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So I'm mostly wondering what happens here. I'm considering biting the bullet on a new build but I don't want to have any hitches. I'm using the ASRock Fatal1ty X99 Killer. It supports x16/x8/x4 if you have a CPU with 28 lanes, which is exactly the route I'm wanting to go. I've got it planned out to run two GPU's, an x4 PCIe SSD, and my x1 sound card. The problem is that before the sound card is put into play, all 28 lanes would be in use, and I'm wondering what exactly would happen. What I'm hoping is that the CPU or board or whatever decides what gets what bandwidth would just automatically make my other card an x8. That way I'd have more lanes which would give me enough for my sound card, and also allow me to get another SSD if I eventually wanted to. Will it work like that, or is there some force at work on the board that says "this slot runs at x16, period"?
 
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it should do x16 on one slot in use and x8/x8 if 2 slots are used but I thought x boards with a plx chip can do x16/x16 on 2 slots ?? now if any 3ed slot comes in to play that may chop down the 2ed x16 to x8 cause its shared with it ??

like with this z87 you gotm 3 slots to the cpu that's 16 lanes if one card is used it gets the full x16 if 2 cards are used they share x16 at x8 by x8 if 3 slots are usd then its x8 x4 and x4 , see.

no mater you canr exceed the total lanes available weather it ''wired'' to the cpu or the chipset
well with anything like you asked theres only so much to go around and be shared ? I don't see anything on the slots and weather if you exceed anypart of this if something become disabled in order to be used ??

like said from here on this board

'' There is also an M.2 slot, which is compatible with PCI Express 3.0 x4 and SATA M.2 modules. If a PCI Express x4 M.2 module is installed, the third PCI Express 3.0 x16 will be disabled.
Read more at http://www.hardwaresecrets.com/asrock-x99-extreme63-1-motherboard/2/#BfXGsfBv5IYMkAjR.99

so I don't see anything on that fatality stating any of this if it does the same or not ??
 

firefoxx04

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Jan 23, 2009
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You would not be using all your lanes to begin with (I think). I think the GPUs would drop down to x8 because two of them in x16 requires 32 lanes.

x8, x8, x4, x1 would give you 21 lanes used.

Another thing to consider is are all the PCIe slots wired to the CPU or the chipset? I am not sure about X99 but I think Z97 has its x16 slots usually wired to the CPU (and a third wired to the chipset). I think that is the case with my board.

Either way, you should be fine. I cannot think of one single gpu (not dual gpu, single board) that requires x16 for full performance. Any performance hit you have would probably be related to bad sli or xfire drivers or poor game optimization.
 

Kezekan

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Dec 9, 2014
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Well running them both at x8 is exactly what I'm wanting to do. I'm just concerned because it says with 28 lanes it'll do x16/x8 on the cards, and I'm wondering if there's a way to just tell it to do x8 on both cards.
 
it should do x16 on one slot in use and x8/x8 if 2 slots are used but I thought x boards with a plx chip can do x16/x16 on 2 slots ?? now if any 3ed slot comes in to play that may chop down the 2ed x16 to x8 cause its shared with it ??

like with this z87 you gotm 3 slots to the cpu that's 16 lanes if one card is used it gets the full x16 if 2 cards are used they share x16 at x8 by x8 if 3 slots are usd then its x8 x4 and x4 , see.

no mater you canr exceed the total lanes available weather it ''wired'' to the cpu or the chipset
 
Solution