PCIe lane count

[MeepsterNotchy]

I have an i7 4770 CPU and an MSI H81M-P33 motherboard. My CPU supports 16 PCIe lanes, but I have a x16 graphics card and a x1 sound card. I read somewhere that the chipset adds its own amount of PCIe lanes. So do I really support for 16 + the chipset amount? Or just 16 ?

 

[techgeek]

I believe that your PCI-E 3.0 lanes (16) would be hardwired to the X16 slot. The chipset (H81) supports 6 additional PCI-E 2.0 lanes. It's from the chipset that the X1 slot would get it's lane.

That said, even if your graphics card only got 8 lanes, its been shown that a graphics card doesn't show any appreciable degradation in performance down to 4 lanes.

If you want to be certain, download GPU-Z and you'll see PCI-E Bus Interface. Sometimes what's displayed here will be less than you expect, in this case, just hit the question mark icon and then Start Render Test and then recheck the PCI-E Bus Interface.

 

[4745454b]

http://www.tomshardware.com/reviews/core-i7-4770k-haswell-review,3521-9.html

If you look in the chart, in the upper left it shows the possible PCIe configs. It still supports "up to 8x PCI express 2.0". This runs through the chipset/PCH/Southbridge/whatever Intel calls it now. The info here flows to the CPU over the DMI. DMI doesn't use the 16x lanes like you thinking of.

https://en.wikipedia.org/wiki/Direct_Media_Interface