GPU only runs at PCIe 3.0 8x and not 16x

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EXCellR8

Diamond Member
Sep 1, 2010
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Interesting... you'd think they'd be a bit more careful about where the labels get stuck. I can understand them being arbitrarily placed on the main part of the PCB but anything near the connector that isn't perfectly placed is definitely an oversight. I don't think I've run into this before though so perhaps it's just a very slim chance. Glad it worked out though.
 

Markfw

Moderator Emeritus, Elite Member
May 16, 2002
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Also, not an Intel motherboard expert on the later ones, but if you have an M.2 drive, its shares the speed with the primary slot ? (thats a question)
 

cmdrdredd

Lifer
Dec 12, 2001
27,052
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Also, not an Intel motherboard expert on the later ones, but if you have an M.2 drive, its shares the speed with the primary slot ? (thats a question)

Yes and no. You have a total number of lanes on the cpu available and the m.2 slot does share the lanes with GPUs, any network cards, sound boards etc you may have installed. It doesn’t steal lanes but it this is why you can only do 8x/8x SLI with many boards in the consumer market.
 

Markfw

Moderator Emeritus, Elite Member
May 16, 2002
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Yes and no. You have a total number of lanes on the cpu available and the m.2 slot does share the lanes with GPUs, any network cards, sound boards etc you may have installed. It doesn’t steal lanes but it this is why you can only do 8x/8x SLI with many boards in the consumer market.
Well, thats why I posted. I know the new AMD Zen chips have way more lanes, but without trolling, I wanted to at least propose that might have been the problem.

Glad its fixed now.
 

Campy

Senior member
Jun 25, 2010
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Also, not an Intel motherboard expert on the later ones, but if you have an M.2 drive, its shares the speed with the primary slot ? (thats a question)
Not sure but I think the first two x16 slots share the 16 CPU lanes (x16 or x8/x8), while M.2 and everything else goes through the PCH (DMI).
 

cmdrdredd

Lifer
Dec 12, 2001
27,052
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Not sure but I think the first two x16 slots share the 16 CPU lanes (x16 or x8/x8), while M.2 and everything else goes through the PCH (DMI).

The motherboard manual should tel you which ports use the PCH. I think Z370 has a total of 24 with 16 being on the cpu. Generally though the first two PCIe slots share the cpu lanes so if anything is in slot 2 even if it only supports 4x then slot 1 will default to 8x.
 

Dribble

Platinum Member
Aug 9, 2005
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Also, not an Intel motherboard expert on the later ones, but if you have an M.2 drive, its shares the speed with the primary slot ? (thats a question)
It won't effect the gpu as that's on the cpu lanes. You've generally got 20 lanes dedicated to PCIE (so you get x16 + x4 or x8 + x8 + x4). The storage goes through PCH which has 24 lanes attached by a 4 lane link to the cpu. Basically for your average user the Intel solution will not have any problems with lack of lanes.
 
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Campy

Senior member
Jun 25, 2010
785
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The motherboard manual should tel you which ports use the PCH. I think Z370 has a total of 24 with 16 being on the cpu. Generally though the first two PCIe slots share the cpu lanes so if anything is in slot 2 even if it only supports 4x then slot 1 will default to 8x.

I checked my Z270 motherboard manual and it only supports 1x16 or 2x8, but apparently some motherboards can support 1x8 + 2x4.

I found this which shows the PCIe lane layout on the Intel Z370 platform, it's essentially the same for Z270 and Z370:

small_z370-chipset.png
 

cmdrdredd

Lifer
Dec 12, 2001
27,052
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I checked my Z270 motherboard manual and it only supports 1x16 or 2x8, but apparently some motherboards can support 1x8 + 2x4.

I found this which shows the PCIe lane layout on the Intel Z370 platform, it's essentially the same for Z270 and Z370:

small_z370-chipset.png

Right...most high end boards have extra lanes on the PCH as mentioned. For 99% of all users this is not a problem