[SOLVED] Crucial P2 1TB SSD only doing 1600GB/sec max read speed ?

[kamikazilucas]

i got this ssd that is supposed to do 2400 and it is doing nowhere near that, i had AHCI turned on in bios but it didnt fix it ?

 

[USAFRet]

i got this ssd that is supposed to do 2400 and it is doing nowhere near that, i had AHCI turned on in bios but it didnt fix it

What motherboard?
Testing this with what application?

 

[kamikazilucas]

and

What motherboard?
Testing this with what application?

motherboard is asus prime b450 plus, crystal disk mark is the app

 

[kamikazilucas]

What motherboard?
Testing this with what application?

https://imgur.com/a/ldL5cDa

ok so the ssd is running slow because it is for some reason in pcie 2x4 mode and not pcie 3 even though its in a x16 slot, idk how to change it though

 

[USAFRet]

https://imgur.com/a/ldL5cDa

ok so the ssd is running slow because it is for some reason in pcie 2x4 mode and not pcie 3 even though its in a x16 slot, idk how to change it though

Is this in the native M.2 port?

 

[kamikazilucas]

Is this in the native M.2 port?

no i am using a pcie 3 adapter

 

[USAFRet]

no i am using a pcie 3 adapter

Then I would figure the adapter is the cause.

 

[kamikazilucas]

Then I would figure the adapter is the cause.

but the adapter says its pcie 3

 

[USAFRet]

but the adapter says its pcie 3

Be that as it may, not all adapters are the same, or good quality.

Options:

1. Change the adapter.
2. Move that drive to the M.2 port on the motherboard.
3. Live with it.

 

[Maxxify]

https://imgur.com/a/ldL5cDa

ok so the ssd is running slow because it is for some reason in pcie 2x4 mode and not pcie 3 even though its in a x16 slot, idk how to change it though

Transfer mode is x4 PCIe 2.0 which is typical for the CHIPSET on a B450-based board. Adapter has no impact on this as you're bottlenecked by the chipset/PCH.

PCIe 2.0 transfers at 5 GT/s per lane, so 20 GT/s in this case, and considering 8 bits/byte and 8b/10b encoding that comes out to 2 GB/s. Overhead is at least 10%, so 1.8 GB/s at the most is expected. That would be at maximum queue depth and thread count, keeping in mind the entire chipset bandwidth is limited to that amount, which likely includes other devices (e.g. SATA).

The primary M.2 slot uses CPU lanes and would thus run at x4 PCIe 3.0. An adapter will only hit those speeds using CPU and not chipset lanes - which would mean no discrete GPU.

 

[kamikazilucas]

Transfer mode is x4 PCIe 2.0 which is typical for the CHIPSET on a B450-based board. Adapter has no impact on this as you're bottlenecked by the chipset/PCH.

PCIe 2.0 transfers at 5 GT/s per lane, so 20 GT/s in this case, and considering 8 bits/byte and 8b/10b encoding that comes out to 2 GB/s. Overhead is at least 10%, so 1.8 GB/s at the most is expected. That would be at maximum queue depth and thread count, keeping in mind the entire chipset bandwidth is limited to that amount, which likely includes other devices (e.g. SATA).

The primary M.2 slot uses CPU lanes and would thus run at x4 PCIe 3.0. An adapter will only hit those speeds using CPU and not chipset lanes - which would mean no discrete GPU.

but the motherboard says both 16 slots are pice 3

 

[kamikazilucas]

Transfer mode is x4 PCIe 2.0 which is typical for the CHIPSET on a B450-based board. Adapter has no impact on this as you're bottlenecked by the chipset/PCH.

PCIe 2.0 transfers at 5 GT/s per lane, so 20 GT/s in this case, and considering 8 bits/byte and 8b/10b encoding that comes out to 2 GB/s. Overhead is at least 10%, so 1.8 GB/s at the most is expected. That would be at maximum queue depth and thread count, keeping in mind the entire chipset bandwidth is limited to that amount, which likely includes other devices (e.g. SATA).

The primary M.2 slot uses CPU lanes and would thus run at x4 PCIe 3.0. An adapter will only hit those speeds using CPU and not chipset lanes - which would mean no discrete GPU.

so if i made it so my gpu used 8 lanes instead of 16 i would have more cpu lanes to use on my ssd and then i can make it run at full speed ?

 

[Maxxify]

but the motherboard says both 16 slots are pice 3

See here

so if i made it so my gpu used 8 lanes instead of 16 i would have more cpu lanes to use on my ssd and then i can make it run at full speed ?

There's no way to make it faster on that board unless you run no GPU at all. It doesn't bifurcate or anything else.

 

[kamikazilucas]

See here



There's no way to make it faster on that board unless you run no GPU at all. It doesn't bifurcate or anything else.

ok thanks, idgi why dosent the new cpus have more than 20 lanes, they litterally only give you enough for 1 gpu and ssd and thats it

 

[USAFRet]

ok thanks, idgi why dosent the new cpus have more than 20 lanes, they litterally only give you enough for 1 gpu and ssd and thats it

$$ and demand.

Few people have a need for more than one high speed M.2 drive.
In typical use, few people can tell the difference between various flavors of SSD.

 

[SkyNetRising]

ok thanks, idgi why dosent the new cpus have more than 20 lanes, they litterally only give you enough for 1 gpu and ssd and thats it

You can put graphics card into second PCIE x16 slot (PCIE 2.0 x4) and
put PCIE M.2 adapter into top PCIE 3.0 x16 slot.

You'll get full speed on your M.2 drive this way. Graphics card bandwidth will suffer a bit though.

 

[kamikazilucas]

You can put graphics card into second PCIE x16 slot (PCIE 2.0 x4) and
put PCIE M.2 adapter into top PCIE 3.0 x16 slot.

You'll get full speed on your M.2 drive this way. Graphics card bandwidth will suffer a bit though.

yeah i could but when i get a new gpu which i am gonna soon it will bottleneck it alot

 

[SkyNetRising]

yeah i could but when i get a new gpu which i am gonna soon it will bottleneck it alot

Depends on graphics card. Might not be too much.

 

[Maxxify]

yeah i could but when i get a new gpu which i am gonna soon it will bottleneck it alot

GPU on x4 PCIe 2.0 is definitely pushing it a bit. TPU tested this with a 2080 Ti and found ~20% drop in FPS.

ok thanks, idgi why dosent the new cpus have more than 20 lanes, they litterally only give you enough for 1 gpu and ssd and thats it

It's a B450 limitation. B550 and X570 would be fine, assuming an appropriate CPU. To be fair, your limitation isn't a big deal with the 1TB P2.

 

[kamikazilucas]

GPU on x4 PCIe 2.0 is definitely pushing it a bit. TPU tested this with a 2080 Ti and found ~20% drop in FPS.



It's a B450 limitation. B550 and X570 would be fine, assuming an appropriate CPU. To be fair, your limitation isn't a big deal with the 1TB P2.

are b550 chipset lanes pcie 3 or 4?

 

[USAFRet]

are b550 chipset lanes pcie 3 or 4?

It appears to be 4.0
https://www.amd.com/en/chipsets/b550

But don't change the motherboard just to bump up from 3.0 to 4.0.

 

[kamikazilucas]

It appears to be 4.0
https://www.amd.com/en/chipsets/b550

But don't change the motherboard just to bump up from 3.0 to 4.0.

im not going to though like already mentioned the chipset lanes on b450 are not 3.0 they are 2.0 thats the problem lol

 

[USAFRet]

im not going to though like already mentioned the chipset lanes on b450 are not 3.0 they are 2.0 thats the problem lol

Right.
Hence the performance of your current drive.

 

[Maxxify]

are b550 chipset lanes pcie 3 or 4?

B550 is PCIe 3.0 downstream over the chipset so any single drive would be x4 PCIe 3.0.

 

[logainofhades]

B450 is 2.0, B550 is 3.0, and X570 is 4.0. Do you already have a drive, in the primary M.2 slot, in your motherboard?