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C6H, split PCI-E lanes more specifically

Blue_Monkey
Level 7
Goodday

I have a Crosshair VI Hero and a Ryzen 7 1700. Additionally I use a RTX 2080 Ti and for video encoding a GTX 970, along a M.2 SSD (Samsung 950 Evo).
In total there are 24 PCI-E lanes available, but it splits them like this:
x8 for RTX 2080 Ti
x8 for GTX 970
x4 for PCI-E M.2

Is there a way to split them like this using x16 slot 1 & 2 and M.2 slot? I tried with forcing the GTX 970 into x4 but then it still allocates x8 ONLY to the RTX 2080 Ti, but I wish to have this:
x16 RTX 2080 Ti
x4 GTX 970
x4 PCI-E M.2

Is there a way to do this? If not, is this planned for the upcoming x570 motherboards with Ryzen 7 3xyz?

Greez
10,010 Views
9 REPLIES 9

SaLSouL
Level 10
its under advanced>onboard Devices configuration> you can manually adjust pcie lanes multiplier if it helps..

*1 PCIeX4_3 slot shares bandwidth with PCIeX1_1, PCIeX1_2 and PCIeX1_3.
https://valid.x86.fr/s8b4u7

SaLSouL wrote:
its under advanced>onboard Devices configuration> you can manually adjust pcie lanes multiplier if it helps..

*1 PCIeX4_3 slot shares bandwidth with PCIeX1_1, PCIeX1_2 and PCIeX1_3.


This is for that specific slot, but otherwise I couldn't find anything.
I could force the second x16 slot into x4, but my first x16 stayed at x8 3.0 speed, despite enough PCI-E lanes to make it happen.

Blue Monkey wrote:
This is for that specific slot, but otherwise I couldn't find anything.
I could force the second x16 slot into x4, but my first x16 stayed at x8 3.0 speed, despite enough PCI-E lanes to make it happen.



I dont think what your asking is possible
the CPU has 20 lanes
the rest are provided by the CHIPSET for USB & SATA

you cannot set individual lanes that are not supported

x16 single
dual x8/x8
+ m2 x4 ssd they are the only ones supported by your MB
https://valid.x86.fr/s8b4u7

SaLSouL wrote:
I dont think what your asking is possible
the CPU has 20 lanes
the rest are provided by the CHIPSET for USB & SATA

you cannot set individual lanes that are not supported

x16 single
dual x8/x8
+ m2 x4 ssd they are the only ones supported by your MB


Ah I was thinking CPU provides 24 lanes, my mistake

Blue Monkey wrote:
Ah I was thinking CPU provides 24 lanes, my mistake



It would be quite handy if it did, but not many boards support it,

here is an interesting read if you get time, your actually not missing out on much by running at x8 anyway
https://www.techpowerup.com/reviews/NVIDIA/GeForce_RTX_2080_Ti_PCI-Express_Scaling/7.html
https://valid.x86.fr/s8b4u7

SaLSouL wrote:
It would be quite handy if it did, but not many boards support it,

here is an interesting read if you get time, your actually not missing out on much by running at x8 anyway
https://www.techpowerup.com/reviews/NVIDIA/GeForce_RTX_2080_Ti_PCI-Express_Scaling/7.html


I wonder if this is applicable to my situation. I lose a couple of frames, but also I wonder if this impacts the performance of NVENC, in the end you see it sends the frames to my GTX 970 for handling, so I suspect this further impacts my PCI-E bandwith ... what do you think?

I have ch7 with similar spec M.2 + 2 video cards gtx 1070+gt 710 im using the last slot of pcie 4x for my gt 710 to keep my 1070 to 16 x

rambobino wrote:
I have ch7 with similar spec M.2 + 2 video cards gtx 1070+gt 710 im using the last slot of pcie 4x for my gt 710 to keep my 1070 to 16 x



thats one of the only differences between the C6h and c7h , unfortunately for the OP the 2nd and 3rd slots are locked at x8 & x4 respectively whilst the c7h has the option.

c6h slots assignment
79814

c7h slot assignment
79815
https://valid.x86.fr/s8b4u7

SaLSouL wrote:
thats one of the only differences between the C6h and c7h , unfortunately for the OP the 2nd and 3rd slots are locked at x8 & x4 respectively whilst the c7h has the option.

c6h slots assignment
79814

c7h slot assignment
79815


You can get around this by forcing slot 4 into x4 mode (I think it says its intended for RAID config) - sadly that doesn't put slot 2 into x16 mode - either because there are not enough lanes or the mobo bios is stupid ...