Intel i5 7600 PCIe Lanes Question

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Dylan SJ Perez

Dylan SJ Perez

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Hi, I've bought a new system that includes the i5 7600, I'm using a GTX 1070 and a PCIe Asus wireless card, I've only now noticed that the processor only supports 16 PCIe lanes and I'd be taking up 17, 16 with the GPU and 1 with the wireless card. Unless I'm stupid or wrong, doesn't that mean I'll run into some sort of incompatibility?

Please help me I'm really confused :(

Dylan
 
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J
lol... me too looking at that


way I see it the primary pci-e slot for the graphics card is full x16 full time off the cpu nothing shares the cpu lanes on that board

all the rest of the slots are shared through the chipset lanes

I assume that's why its stated as

this slot is full time x16
1 x PCIe 3.0/2.0 x16 (x16 mode)

all these are through the chipset and shared as there used

1 x PCIe 3.0/2.0 x16 (max at x4 mode) *1
4 x PCIe 3.0/2.0 x1

foot note for them slots not anything to do with the primary for the GPU

*1 PCIe x16_2 slot shares bandwidth with PCIe x1_2 and PCIe x1_3 slots. When PCIe x1_2 and PCIe x1_3 slots are occupied, PCIe x16_2 slot runs at x2 mode.


all that also should be graphed out and spelled out...
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Jwpanz

Jwpanz

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Motherboards usually come with a multiplier chip to allow more PCIe devices to run on a processor than it can technically support. The caveat is that the lanes will run slightly slower. In your case, 17 lanes will will not noticeably affect speeds.
 
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Dylan SJ Perez

Dylan SJ Perez

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Ahhh I see, just to clarify, though it'll work, the GPU will run a tiny bit slower (it doesn't bother me but just wanted to clarify)

Thanks!
 
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Jwpanz

Jwpanz

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17 lanes on a 16 lane chip will barely even show any sort of difference in speeds. Your motherboard compensates for the extra lane. The reduction is so small that you would have to use monitoring software to even pick anything up.
 
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Dylan SJ Perez

Dylan SJ Perez

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Gotcha, thanks!
 
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junkeymonkey

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that depends on what the slot the wireless card is ''wired '' as if its tied to the cpu lanes then yes it will be shared if its to the chipset then no the cpu retains the full x16/8x8

that can be tricky with intel boards on how the manufacture sets the pci-e configuration up like some times adding the M2 will disable a slot or be shared on the cpu or the chipset

Slots: Three PCI Express 3.0/2.0 x16 slots (working at x16/x0/x0, x8/x8/x0 or x8/x4/x4), one PCI Express 2.0 x1 slot, two PCI slots (ASMedia ASM1083 bridge chip), and one Mini PCI Express slot

http://www.hardwaresecrets.com/asrock-z87-extreme6-motherboard/2/


this board only 2 slots are shared on the cpu and will all ways be x16 single card or 8x8 sli

Slots: Two PCI Express 3.0/2.0 x16 slots (working at x16/x0 or x8/x8), one PCI Express 2.0 x16 slot (working at x2), two PCI Express 2.0 x1 slots, and two PCI slots (ASMedia ASM1083 bridge chip)

http://www.hardwaresecrets.com/asus-z87-a-motherboard/2/


so what is your motherboard all we got to do is look it up if we can to see
 
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junkeymonkey

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that best answer don't add up at all and kinda wrong

''Motherboards usually come with a multiplier chip to allow more PCIe devices to run on a processor than it can technically support''

unless its a high end board with a plx chip on it and you pay dearly for that . how do you know he got one of them ?? still don't take away from the fact the CPU only has 16 lanes in that i5 he using ??



 
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Dylan SJ Perez

Dylan SJ Perez

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The motherboard is an Asus B250F, it has 1 16x, 1 8x and 2 1x I believe.

Thanks for the help
 
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Eximo

Eximo

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Intel consumer CPU has 16x "Direct" PCIe lanes, these usually go to the x16 slots and really can't be effected by any other devices in the system. This means 16x/0x or 8x/8x modes supported. Some boards are configured for 8x/4x/4x, usually on 3-way Crossfire supported boards.

The PCH has its own lanes. In the case of Z270 that is 24x PCIe 3.0 lanes of its own. These are connected to the CPU through DMI (Direct Media Interface).

So the CPU has dedicated bandwidth for all your non-GPU, or other high bandwidth, devices.
 
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junkeymonkey

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see what they say here
1 x PCIe 3.0/2.0 x16 (x16 mode)
1 x PCIe 3.0/2.0 x16 (max at x4 mode) *1
4 x PCIe 3.0/2.0 x1

*1 PCIe x16_2 slot shares bandwidth with PCIe x1_2 and PCIe x1_3 slots. When PCIe x1_2 and PCIe x1_3 slots are occupied, PCIe x16_2 slot runs at x2 mode.

https://www.asus.com/us/Motherboards/ROG-STRIX-B250F-GAMING/specifications/


they sure don't have that too straight forward so what slots are dedicated to the CPU and what ones to the chipset ??? the way they got that described the one slot is full time x16 and not shared off the CPU with anything

so that board all the slots except the main pci-e for the graphics card is all through the chipset

so if you do a x-fire and add a 3ed card you alos loose x-fire cause that slot drops to x2

the gpu will all ways be x16 off the cpu no matter what

 
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Dylan SJ Perez

Dylan SJ Perez

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I'm a bit confused, does that mean the card will stay at full speed or slow down? If it slows down will that be by a lot or not?

I'm only planning to use 1 GPU and just 1 1x slot for the wireless card
 
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junkeymonkey

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lol... me too looking at that


way I see it the primary pci-e slot for the graphics card is full x16 full time off the cpu nothing shares the cpu lanes on that board

all the rest of the slots are shared through the chipset lanes

I assume that's why its stated as

this slot is full time x16
1 x PCIe 3.0/2.0 x16 (x16 mode)

all these are through the chipset and shared as there used

1 x PCIe 3.0/2.0 x16 (max at x4 mode) *1
4 x PCIe 3.0/2.0 x1

foot note for them slots not anything to do with the primary for the GPU

*1 PCIe x16_2 slot shares bandwidth with PCIe x1_2 and PCIe x1_3 slots. When PCIe x1_2 and PCIe x1_3 slots are occupied, PCIe x16_2 slot runs at x2 mode.


all that also should be graphed out and spelled out better in the manual of your motherboard ??
 
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Dylan SJ Perez

Dylan SJ Perez

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That's making a lot more sense, so I'd be right in assuming that the GPU works with the CPU while the network card will rely on the board rather than the CPU?
 
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TJ Hooker

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The network card still communicates with the CPU over PCIe, just like the graphics card, it just uses a different path because it's going through the chipset (PCH). But they don't share bandwidth.

To add to what @Eximo said, only Z-series chipsets (e.g. Z270) support splitting the x16 'Direct' PCIe lanes from the CPU, e.g. into x8/x8 or x8/x4/x4. For other chipsets like B250 (which is what your mobo has), the primary x16 slot on the mobo will always have full x16 bandwidth to the CPU and will not share bandwidth with any other slots or connectors.
 
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Dylan SJ Perez

Dylan SJ Perez

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I think i get it now, ill see what the performance is like when i build the system, thanks again.
 
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junkeymonkey

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''That's making a lot more sense, so I'd be right in assuming that the GPU works with the CPU while the network card will rely on the board rather than the CPU? ''

with out downloading that boards manual to see if something different then what I see from the specs that's how I see it

GPU slot fully on the CPU all the rest on the chipset of the board

what TJ said is good /correct

''The network card still communicates with the CPU over PCIe, just like the graphics card, it just uses a different path because it's going through the chipset (PCH). But they don't share bandwidth.'


I thought I put this part in as well but TJ did

''To add to what @Eximo said, only Z-series chipsets (e.g. Z270) support splitting the x16 'Direct' PCIe lanes from the CPU, e.g. into x8/x8 or x8/x4/x4. For other chipsets like B250 (which is what your mobo has), the primary x16 slot on the mobo will always have full x16 bandwidth to the CPU and will not share bandwidth with any other slots or connectors. ''


but that don't pertain to your board but a good answer

 
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