Question NVMe question pcie 3.0 vs pcie 4.0

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Deleted member 2849646

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Hi guys,

I was just doing some research and I came across this nice NVMe SSD:https://www.amazon.co.uk/WD_BLACK-Internal-Gaming-Technology-speeds/dp/B08KFN1KT1

Now my mobo only has pcie 3.0 support, and at x16 that gives me a theoretical maximum of 15800MB/s (according to this: https://www.fullexposure.photography/how-fast-is-pcie-4-0-nvme-vs-pcie-3-0/)

My question is, as the amazon ssd has read speeds of 7000MB/s, will the pcie 3.0 get maximum performance from it in x16 slot, or is there another bottleneck?

Hope the question makes sense. Basically I'm trying to figure out whether this pcie 4.0 rated card will get max read and write speeds advertised on a pcie 3.0 slot connected via an adapter.
 
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Deleted member 2849646

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In a 3.0 port, a 4.0 drive will only see 3.0 performance.

But...what do you actually use this for?
Just interested to know about the limitations from an academic point of view. Makes absolutely no difference to me :). Don't plan on getting either - just wondering whether this wd nvme ssd will get max speeds through pcie as it's theoretical max bandwidth is much higher (double the read speeds ssd can write at)

Or in other words, would putting that nvme ssd in a pcie 3.0 port get the same speeds as putting it in a pcie 4.0 port? Hmmm
 

USAFRet

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Just interested to know about the limitations from an academic point of view. Makes absolutely no difference to me :). Don't plan on getting either - just wondering whether this wd nvme ssd will get max speeds through pcie as it's theoretical max bandwidth is much higher (double the read speeds ssd can write at)

Or in other words, would putting that nvme ssd in a pcie 3.0 port get the same speeds as putting it in a pcie 4.0 port? Hmmm
In a proper PCIe adapter, in a capable port, a PCIe 4.0 drive will see its full benchmark numbers.

In a PCIe 3.0 port, it would only see 3.0 speed.

Performance is dictated by the slowest device in the chain.
Here, the 3.0 port.
 
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Deleted member 2849646

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In a proper PCIe adapter, in a capable port, a PCIe 4.0 drive will see its full benchmark numbers.

In a PCIe 3.0 port, it would only see 3.0 speed.

Performance is dictated by the slowest device in the chain.
Here, the 3.0 port.
I think you missed my point :)

That ssd has read speeds of 7000MB/s. But the bandwidth of pcie 3.0 is PCIe 3.0 16x : 126.4Gb/s x 125 = 15,800MB/s

So basically pcie 3.0 in theory has more than enough bandwidth to get the 7000MB/s out of it. My question is, will the WD SN850 work at 7000MB/s in a pcie 3.0 given the aforementioned, or is there some other bottleneck that limits the speed below 7000B/s?
 
Most consumer boards only have 4 lanes of PCIE running to their NVME slots.
Some cheat and only have 2 PCIE lanes.
So most NVME drives are made to support 4 lanes of PCIE. But some of them only support 2 PCIE lanes.
If you want to spend big bucks on enterprise/server level equipment, you can get drives with more PCIE lane support.
There are a few RAID 4xNVME PCIE 16x cards but they are not there yet in terms of speed .
 

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