Question 9900K PCIE Lanes

[mike041]

Spec'ing a new system, and looking at the 9900k. (with appropriate mobo ofc)

I see the coffee lake only have 16 pcie channels. Which should be find for a 2080ti.

However I also like to run a sound card, which would consume another 8 lanes. This would drop the 2080ti down to x8 vs x16 right?

I can't seem to find any review that show the impact on the 9900 with adding additional PCIe consumers to a build. Anyone have any good links or data to support an argument?

The alternative is to jump to a skylake with a considerable cost increase. (Nothing wrong with AMD, just have a ton of friends at Intel, so trying to support)

Thanks in advance.

 

[bignastyid]

Most motherboards chipset(especially the higher end ones) have additional pci-e lanes. So you'd have 16 plus what the motherboard offers. For example My Z390 Aorus Master(like most if not all Z390 boards) has 24 PCI-e 3.0 lanes.

 

[MadsModsat]

As mentioned above, the motherboard chipset will provide additional PCI-e lanes. I use a PCI-e soundcard and two m.2 NVMe PCI-e SSDs, and I still get the full x16 PCI-e 3.0 speed for my RTX2070 Super, so you'll be perfectly fine running the setup you mentioned with a 2080 Ti and a sound card.

 

[mike041]

Ah so maybe I misunderstood this all along. I assumed a x16 card, would consume 16 lanes on the mobo, which also used 16 lanes on the cpu. So if your peripherals used 24 lanes, to ensure you didn't bottleneck at the mobo or CPU, you would need a x16/x8 mobo (or better) and 24 lanes on the CPU. or put another way

Peripheral

• Video Card - x16
• Sound Card - x8

Mobo
- PCIe - 16/8

Cpu
- PCIe - >24

Where if the CPU is only 16 then it forces the video card to drop down to x8 so I end up with the sytem dropping down the overall capacity to the limiting component, in this case it's the 9900

Peripheral

• Video Card - x8 (16x capable)
• Sound Card - x8

Mobo
- PCIe - 8/8 (16/8 capable)

Cpu
- PCIe - 16 - bottleneck


Thanks again for working through this with me.

 

[bignastyid]

On all the Z390 boards(what you want with a 9900k), the 16 lanes from the CPU only go to the top/main 16x pci-e slot and the motherboards lanes are divided between the remaining pci-e and m.2 slots. You have to look at the motherboards manual/specs for the exact split.