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CPU & PCIe lanes - Confused af... halp plz?

hi_im_snowman

36 months ago

https://ca.pcpartpicker.com/user/hi_im_snowman/saved/fKCFTW

Okay so... That's my prospective build. I think it should be compatible and work fine, but I'm confused as all hell when it comes to PCIe lanes. ARK tells me this i5-7600k has 16 lanes and the GPU takes 16 lanes soo umm, how can I confirm that my M.2 + SSD + GPU will run optimally? Have I chosen the wrong cpu/mobo combo for this build if my intention is to run every component optimally?

Thanks!

Comments

  • 36 months ago
  • 2 points

The CPU does indeed have 16 lanes. However the Chipset has additional PCIe lanes to manage devices aside from the GPU such as the M.2 SSD. Z270 has 24 additional PCIe Gen 3.0 lanes.

In your build the CPU will provide 16 lanes to the GPU and the M.2 slot will be wired to use 4 of those chipset lanes.

Either way its a non issue as Nvidia GPU's can drop down to x8 lanes without any real world impact and infact that's what happens why you see all these various SLI configs bar the higher end X99 CPU's.

  • 36 months ago
  • 1 point

You'll be fine. Like Radox said, the CPU and chipset don't use the same PCIe lanes. However, you should check out the manufacturer's caveats about M.2 and SATA ports:

  • 2 The M.2_1 socket shares SATA_1 port when use M.2 SATA mode device. Adjust BIOS settings to use a SATA device.
  • 3 The M.2_2 socket shares SATA_56 ports when use M.2 PCIE mode device in X4 mode. Adjust BIOS settings to use SATA devices.
  • 7 The USB 3.1 front panel connector shares bandwidth with PCIE_x1_2 and PCIE_x1_4. If the USB 3.1 front header is connected, PCIE_x1_2 and PCIE_x1_4 will be disabled.

https://www.asus.com/us/Motherboards/ROG-STRIX-Z270E-GAMING/specifications/

For example, when you plug in the 600p into the 1st M.2 socket, don't put the 750 Evo into SATA port 1.

  • 36 months ago
  • 2 points

Just a slight tweak. The conflict occurs when the M.2 drive uses Sata bandwidth not PCIe lanes. So he would be fine using the Intel 600p in the first M.2 slot and the 750 Evo in the 1st sata slot.

Now there would be a conflict if he adds a second M.2 drive with PCIe lane requirements to the PC whilst also using SATA port 5 or 6

  • 36 months ago
  • 1 point

ohh i see, gotcha. Thanks for the info gentlemen!

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