2 NVMe SSD's

[Mista G]

I have a B450 MSI Gaming Pro Carbon and already have 1 NVMe SSD installed and looking to add another, will it impact my system performance having 2 installed?

[SupaKomputa]

NO.

[Mista G]

Oh cool, so no impact to my graphics card etc?

 

Here's the blurb from the manual:

1x PCIe 3.0 x16 slot (PCI_E1)
Supports x16 speed with AMD® Ryzen™ 1st and 2nd Generation processors
Supports x8 speed with AMD® Ryzen™ with Radeon Vega Graphics processors
Supports x4 speed with AMD® Athlon™ with Radeon™ Vega Graphics Processors
1x PCIe 2.0 x16 slot (PCI_E4, supports x4 mode)*/ **
3x PCIe 2.0 x1 slots*
* PCI_E2, PCI_E3, PCI_E4 and PCI_E5 slots will be unavailable when installing
M.2 PCIe SSD in M2_2 slot.
** PCI_E4 will run x1 speed when installing devices in any PCIe 2.0x1 slot.

 

AMD® B450 Chipset

4x SATA 6Gb/s ports

1x M.2 slot (M2_2, Key M)*

Supports PCIe 2.0 x4 2242/ 2260 /2280 storage devices 

AMD® CPU

1x M.2 slot (M2_1, Key M)**

Supports PCIe 3.0 x4 (AMD® Ryzen 1st and 2nd Generation/ Ryzen™ with Radeon™ Vega Graphics) or PCIe 3.0 x2 (AMD® Athlon™ with Radeon™ Vega Graphics) and SATA 6Gb/s

Supports 2242/ 2260 /2280/ 22110 storage devices 

2x SATA 6Gb/s ports** 

PCI_E2, PCI_E3, PCI_E4 and PCI_E5 slots will be unavailable when installing 

M.2 PCIe SSD in M2_2 slot. 

** SATA5 and SATA6 ports will be unavailable when installing a M.2 device in M2_1 slot.

[mariushm]

The first m.2 connector has 4 pci-e v3.0 lanes directly from processor, separate from the 16 pci-e lanes of the video card, so video card performance is not affected.  As they're 4 pci-e 3.0 lanes, you get up to 4 x 970 MB/s in both directions.

 

The second m.2 connector receives 4 pci-e v2.0 lanes from the chipset, so again video card performance is not affected because that uses pci-e lanes from processor, it's completely separate  thing.

However, keep in mind they're pci-e v2.0 lanes, where each lane has a maximum speed of 500 MB/s, so that connector can do maximum 4 x 500 MB/s = 2 GB/s

If you use a cheaper SSD with a controller that can do maximum pci-e x2, that SSD will run at maximum 1 GB/s

 

The chipset only creates 6 pci-e lanes, so it can't give pci-e lanes to the pci-e x4 slot (which is the second pci-e x16 slot in physical form) and the 3 pci-e x1 slots and the m.2 connector at the same time.

If you install a M.2 nvme ssd in that second M.2 connector, all those pci-e slots become disabled, unusable. You can install SATA M.2 SSD and then the pci-e slots will continue to work.

 

Even if you don't install a M.2 nvme SSD, that pci-e x4 slot is x4 only if you don't insert cards in the pci-e x1 slots - if you insert even one card in any of the pci-e x1 slots, that pci-e x4 slot becomes pci-e x1 slot.

 

so with this particular motherboard, it's kinda not worth it to install a nvme ssd in the second connector, because it makes it hard to use the other pci-e slots (you're left with just the 2nd pci-e x16 slot which is downgraded to pci-e x1 speeds)

 

[Mista G]

@mariushm Thanks for that superb reply, really appreciate that!

 

Not going to use the remaining PCIE slots, only wanted to expand on storage using M.2 drives not SATA.

 

I was going to buy this to populate the second M.2 slot:

 

https://www.amazon.co.uk/Sabrent-Rocket-NVMe-Hochleistungs-Solid-State-Laufwerk-SB-ROCKET-512/dp/B07KGMBCKD?ref_=Oct_DLandingS_c5042b65_2&smid=A3OPWMF9XBYSSI