Running Out of PCIe Lanes

[GeoSquigg]

I have a 2200g on a b450 chipset. Because of the apu, I only have 8 lanes availabl. I know i can run a graphics card at x8 speed and have minimal, if any, decrease in performance. My question is, what would happen if I had NVMe storage?? Couldn't find anything and I'm genuinely curious. 

[Fasauceome]

NVMe will take the dedicated lanes built into ryzen. It has 4 separate for a drive,and a second NVMe drive will take from the chipset.

[GeoSquigg]

1 minute ago, fasauceome said:

NVMe will take the dedicated lanes built into ryzen. It has 4 separate for a drive,and a second NVMe drive will take from the chipset.

Having the 2 drives and Say I add a usb card and a sata expansion card, both being x1. Would the graphics card just run at x6 speeds ??

 

All just hypothetical, just trying to figure out how it works lol

[porina]

The x1 devices would run off the chipset lanes, not CPU lanes. So you still have 8x to GPU.

 

Edit: double check the mobo manual to see which slots are connected to where.

[Fasauceome]

5 minutes ago, GeoSquigg said:

Having the 2 drives and Say I add a usb card and a sata expansion card, both being x1. Would the graphics card just run at x6 speeds ??

 

All just hypothetical, just trying to figure out how it works lol

A GPU can't tun at x6, the only available modes are x16, x8, and x4.

[Mira Yurizaki]

11 minutes ago, GeoSquigg said:

I have a 2200g on a b450 chipset. Because of the apu, I only have 8 lanes availabl. I know i can run a graphics card at x8 speed and have minimal, if any, decrease in performance. My question is, what would happen if I had NVMe storage?? Couldn't find anything and I'm genuinely curious. 

Zen processors have 4 additional lanes for generic use. This is normally assigned to the NVMe slot.

[GeoSquigg]

3 minutes ago, fasauceome said:

A GPU can't tun at x6, the only available modes are x16, x8, and x4.

 

7 minutes ago, porina said:

The x1 devices would run off the chipset lanes, not CPU lanes. So you still have 8x to GPU.

 

2 minutes ago, Mira Yurizaki said:

Zen processors have 4 additional lanes for generic use. This is normally assigned to the NVMe slot.

If I'm understanding this right,

 

if i had the 2 x4 drives and 2 x1 cards, the gpu would run at x4 speed(since htats the highest available/compatible speed)? Or Would something get disabled

 

[Mira Yurizaki]

1 minute ago, GeoSquigg said:

 

If I'm understanding this right,

 

if i had the 2 x4 drives and 2 x1 cards, the gpu would run at x4 speed(since htats the highest available/compatible speed)? Or Would something get disabled

 

No.

 

PCIe x16 slots meant for video cards always get their own set of PCIe lanes. Nothing else will touch it (well, unless you're using an HEDT platform but that's another can of worms). The additional PCIe lanes come from other sources, primarily from the chipset.

[porina]

27 minutes ago, GeoSquigg said:

If I'm understanding this right,

 

if i had the 2 x4 drives and 2 x1 cards, the gpu would run at x4 speed(since htats the highest available/compatible speed)? Or Would something get disabled

What is your mobo?

 

You could have up to 16x from CPU to GPU

You have one 4x from CPU to M.2 NVMe

All other slots will connect to chipset lanes. I understand B450 does not support splitting the CPU lanes to two slots.

[Sovek]

37 minutes ago, Mira Yurizaki said:

Zen processors have 4 additional lanes for generic use. This is normally assigned to the NVMe slot.

so if I'm reading this right, Ryzen has 20 PCI-E lanes, 16 for the GPU and 4 for NVME use? kinda wanna rip out the current m.2 drive and get an NVME drive now....

[porina]

Just looked up OP's mobo in profile, and based on product page (not looked in manual).

 

It has:

16x slot from CPU, supporting up to 16x PCIe 3.0 depending on CPU

16x slot running at 4x PCIe 2.0 if the 1x slots are not used, and at 2x if they are.

16x slot running at 1x PCIe 2.0

1x slot running at 1x PCIe 2.0

 

There are two M.2 connectors, both supporting PCIe NVMe drives. One supports 4x 3.0, the other supports 2x 3.0 only.

 

I'd assume the 16x 3.0 slot, and M.2 4x are the two connected to the CPU, and the others are all connected via chipset.

 

Edit: B450 chipset has 6 PCIe 2.0 lanes for general use. This ties up with the up to 4x to slots, and 2x to 2nd M.2 connector. Gigabytes web page probably has a typo saying the M.2 2x is PCIe 3.0 when it is probably 2.0.

[Mira Yurizaki]

9 minutes ago, Sovek said:

so if I'm reading this right, Ryzen has 20 PCI-E lanes, 16 for the GPU and 4 for NVME use? kinda wanna rip out the current m.2 drive and get an NVME drive now....

Yes, except for the APUs, which only have 8 lanes for the GPU.