Lane sharing on Z370 pro gaming i7

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   I have an EVGA 1080ti FTW3 in PCIE 2 (#1 x16 slot). I also have a SoundBlaster ZxR (PCIe x1 + daughter board with decent length of cable) to fit in there someplace, but am realizing now that I don't think my options are ideal. PCIE 1 would not do the gpu/cpu any favors with cooling. PCIE 3 is blocking two of the three gpu fans.  PCIE 4 definitely would reduce lanes for the gpu. PCIE 5 I think would also reduce lanes. 
I can't find an exact map of lanes, but I think all three of the x16 slots use the CPU lanes. I was hoping the third would use the chipset lanes, but the manual only references that slot as being part of an 8/4/4 configuration with three graphics cards. It makes no mention that I can find about that slot if used without anything in PCIE 4 (the #2 x16 slot). Am I correct thinking this would reduce the gpu lanes to 8 (hence 8/0/4)? 

I also have two NVME SSDs, and now realize they will be potentially bottlenecked if in use simultaneously since they need to fit through the 4 lanes between chipset and CPU. 

So if I'm correct about this:

1) does it even matter in real usage terms?

2) which would be the best slot for the sound card (I'm thinking it has to be PCIE 5 with the daughter board above it)?

when researching this board, it had the features I wanted. I guess I didn't think the top ASRock board would actually end up limiting me in these ways. Or is it?

EDIT: I found in a video review that the bottom PCIe slot is actually an x4 on the chipset, which makes it an ideal slot for the sound card. I couldn't find that info in the manual - just for my own education, can anyone point me to where this is clarified in the manual? Perhaps I read it but didn't recognize this specifically...

EDIT: this video apparently has that wrong. All three appear to be on the CPU (not 2 CPU and one PCH - see below).

Edited by rangoon - 19 Dec 2017 at 9:52am

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rangoon Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 13 Dec 2017 Status: Offline Points: 12	Post Options Post Reply Quote rangoon Report Post Thanks(0) Quote Reply Topic: Lane sharing on Z370 pro gaming i7 Posted: 13 Dec 2017 at 1:10pm
	I have an EVGA 1080ti FTW3 in PCIE 2 (#1 x16 slot). I also have a SoundBlaster ZxR (PCIe x1 + daughter board with decent length of cable) to fit in there someplace, but am realizing now that I don't think my options are ideal. PCIE 1 would not do the gpu/cpu any favors with cooling. PCIE 3 is blocking two of the three gpu fans. PCIE 4 definitely would reduce lanes for the gpu. PCIE 5 I think would also reduce lanes. I can't find an exact map of lanes, but I think all three of the x16 slots use the CPU lanes. I was hoping the third would use the chipset lanes, but the manual only references that slot as being part of an 8/4/4 configuration with three graphics cards. It makes no mention that I can find about that slot if used without anything in PCIE 4 (the #2 x16 slot). Am I correct thinking this would reduce the gpu lanes to 8 (hence 8/0/4)? I also have two NVME SSDs, and now realize they will be potentially bottlenecked if in use simultaneously since they need to fit through the 4 lanes between chipset and CPU. So if I'm correct about this: 1) does it even matter in real usage terms? 2) which would be the best slot for the sound card (I'm thinking it has to be PCIE 5 with the daughter board above it)? when researching this board, it had the features I wanted. I guess I didn't think the top ASRock board would actually end up limiting me in these ways. Or is it? EDIT: I found in a video review that the bottom PCIe slot is actually an x4 on the chipset, which makes it an ideal slot for the sound card. I couldn't find that info in the manual - just for my own education, can anyone point me to where this is clarified in the manual? Perhaps I read it but didn't recognize this specifically... EDIT: this video apparently has that wrong. All three appear to be on the CPU (not 2 CPU and one PCH - see below). Edited by rangoon - 19 Dec 2017 at 9:52am

rangoon Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 13 Dec 2017 Status: Offline Points: 12	Post Options Post Reply Quote rangoon Report Post Thanks(0) Quote Reply Posted: 19 Dec 2017 at 9:50am
	In case this helps anyone, I confirmed that if the 3rd PCIe x16 slot on this board (or the 2nd for that matter) is occupied, the 1st runs in x8 mode (and the 2nd and 3rd x4). That video I referenced was wrong. I placed my sound card in that third slot and GPU-Z showed the video card running in x8. I removed the card and GPU-Z showed the video card running x16. Edited by rangoon - 19 Dec 2017 at 9:53am