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PCIe lanes

ttonk81
By ttonk81
in CPUs, Motherboards, and Memory
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Go to solution Solved by RONOTHAN##,

I do want to preface this by saying that the question you're asking isn't the right question. The amount of PCIe lanes you're using isn't really relevant to any performance benefit (outside of knowing what is connected to the CPU direct, what's connected to the chipset, and how much bandwidth the chipset has), nor is the amount of lanes the CPU has (with some exceptions on platforms that have different CPUs with different bandwidth layouts, though only technically) or how many lanes the chipset has. All that matters is the motherboard and how everything is wired up. The chipset and CPU lanes available only mean something if the motherboard uses them, think of them as an upper limit, and there are plenty of boards that don't use them all (I.E. boards like the Strix X570I, it just doesn't have enough physical space to fit all the features of the X570 chipset). 

 

The way to figure out what you have spare is to look at what connectors you have left, and cross reference that with the motherboard manual to see if any of them share bandwidth. On that board, the only things that share bandwidth are the top two x16 slots (I.E. if the top slot is populated, they run at x16/x0, but if both are populated they run at x8/x8), and the bottom PCIe x16 slot shares with the 2nd x1 slot (I'm assuming that means that if the 2nd x1 slot is populated, the bottom PCIe slot drops to x2 of bandwidth instead of the standard x4, but unfortunately they aren't very descript with that). 

 

21 minutes ago, ttonk81 said:

I'm considering getting an Elgato 4K60 Pro MK2 capture card but want to make sure I have enough PCIe lanes and won't get issues.

It'll work. If you want it to be hooked up directly to the CPU as some capture cards can have issues running through the chipset, plug it into the 2nd PCIe slot and you should have no issues. If you want to use it through the chipset so your GPU gets all the PCIe lanes (slight performance improvement, though in the low single digit percentages), plug it into the bottom PCIe slot and make sure your USB expansion card is not in the bottom PCIe x1 slot, either moving it to the upper x1 slot or swapping it out for a hub. 

 

26 minutes ago, ttonk81 said:

Also, the motherboard has 8 SATA connectors, would I be able to connect 8 SATA SSD along with the 2 NVMe SSD with no issues?

Yes, that board doesn't share bandwidth with the SATA connectors. Some boards do, my X570 Master does for instance, so don't assume that will be the case with every board, but it's also not a guaranteed thing where they definitely will share bandwidth or definitely won't share bandwidth. The motherboard manual will say either way. 

Posted

I'm trying to calculate how many PCIe lanes I and currently using and what I have spare but I'm not 100% sure how to do so.

 

I have a Ryzen 9 5900x in a ROG Strix x570-E Gaming WIFI II motherboard

From my understanding, the 5900x has 20 PCIe 4.0 lanes (16 used by the GPU (EVGA RTX 3090) and 4 by the primary NVME drive (Samsung 980 PRO))

x570 chipset has PCIe 4.0 ×16 so in total I have 36 lanes?

 

In total I have 2x NVMe SSD, 4x SATA SSD, 1x PCIe USB expansion card (considering removing this and using a USB hub instead)

I'm considering getting an Elgato 4K60 Pro MK2 capture card but want to make sure I have enough PCIe lanes and won't get issues.

Also, the motherboard has 8 SATA connectors, would I be able to connect 8 SATA SSD along with the 2 NVMe SSD with no issues?

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I do want to preface this by saying that the question you're asking isn't the right question. The amount of PCIe lanes you're using isn't really relevant to any performance benefit (outside of knowing what is connected to the CPU direct, what's connected to the chipset, and how much bandwidth the chipset has), nor is the amount of lanes the CPU has (with some exceptions on platforms that have different CPUs with different bandwidth layouts, though only technically) or how many lanes the chipset has. All that matters is the motherboard and how everything is wired up. The chipset and CPU lanes available only mean something if the motherboard uses them, think of them as an upper limit, and there are plenty of boards that don't use them all (I.E. boards like the Strix X570I, it just doesn't have enough physical space to fit all the features of the X570 chipset). 

 

The way to figure out what you have spare is to look at what connectors you have left, and cross reference that with the motherboard manual to see if any of them share bandwidth. On that board, the only things that share bandwidth are the top two x16 slots (I.E. if the top slot is populated, they run at x16/x0, but if both are populated they run at x8/x8), and the bottom PCIe x16 slot shares with the 2nd x1 slot (I'm assuming that means that if the 2nd x1 slot is populated, the bottom PCIe slot drops to x2 of bandwidth instead of the standard x4, but unfortunately they aren't very descript with that). 

 

21 minutes ago, ttonk81 said:

I'm considering getting an Elgato 4K60 Pro MK2 capture card but want to make sure I have enough PCIe lanes and won't get issues.

It'll work. If you want it to be hooked up directly to the CPU as some capture cards can have issues running through the chipset, plug it into the 2nd PCIe slot and you should have no issues. If you want to use it through the chipset so your GPU gets all the PCIe lanes (slight performance improvement, though in the low single digit percentages), plug it into the bottom PCIe slot and make sure your USB expansion card is not in the bottom PCIe x1 slot, either moving it to the upper x1 slot or swapping it out for a hub. 

 

26 minutes ago, ttonk81 said:

Also, the motherboard has 8 SATA connectors, would I be able to connect 8 SATA SSD along with the 2 NVMe SSD with no issues?

Yes, that board doesn't share bandwidth with the SATA connectors. Some boards do, my X570 Master does for instance, so don't assume that will be the case with every board, but it's also not a guaranteed thing where they definitely will share bandwidth or definitely won't share bandwidth. The motherboard manual will say either way. 

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