PCI_E3 speed on X870E Tomahawk

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artemii19915a902e5

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I wanted to expand my storage I have bought an adapter https://www.glotrends-store.com/pro...0-x4-adapter-with-m2-heatsink-for-m2-nvme-ssd as the motherboard has PCI_E3 which supposed to support PCIe 4.0 x4 from the Chipset (like around 8GB/s).

However tools like CrystalDiskMark tell me that the adapter is either runs as PCIe 4.0 x2 or PCIe 3.0 x4 instead of PCIe 4.0 x4 as the speed is around 4GBS/s instead of 7-8 GB/s. All my SSDs are the same model in other slots (aside Gen 5) and the benchmark showed around 7GB/s for all of them. I decided to go to BIOS and changed a setting for chipset pcie from auto to Gen 4.0. However it hasn't changed anything.

Am I missing some additional setting I should enable or just the adapter does not produce the expected speed?
 
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can you try the adapter on other slot though? does it make any different if it's on Pcie1?
and is BIOS up to date?
 
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What model M.2 drive you have installed?
And can you provide CrystalDiskMark screenshot?

The issue been tested, but can't be duplicated:
Test configuration:
MB: X870E TOMAHAWK WIFI
BIOS: 2A90, 2A91
CPU: Ryzen 5 9600
M2_1 (CPU): MSI SPATIUM M390 1TB
M2_3 (Chipset): MSI SPATIUM M450 1TB
M2_4 (Chipset): MSI SPATIUM M450 1TB
PCI_E3 (Chipset): MSI SPATIUM M480 PRO 4TB
PCIE M.2 adapter card is MSI M.2 XPANDER AERO GEN4


CrystalDiskMark settings:
Settings > Default
Profile > Default
image014.png


CrystalDiskMark settings:
Settings > NVMe SSD
Profile > Default
image015.png
 
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artemii19915a902e5 said:
However tools like CrystalDiskMark tell me that the adapter is either runs as PCIe 4.0 x2 or PCIe 3.0 x4 instead of PCIe 4.0 x4 as the speed is around 4GBS/s instead of 7-8 GB/s.
Click to expand...

From my opinion not perfect M.2 physical installation is caused this.
Re-seat the M.2 drive physically.
Tip: When you install the M.2 drive in this bracket and push it down,
before use screw to secure the drive:
After pressing it down keep pressing strong (but not too strong) with a finger from one side of the corner vertically in the direction toward the pins
and while keep pressing install the screw, then release it.
For example: [blue = direction force to be pressed], [orange = which corner to keep constant pressing with finger until the screw is set]

Screenshot 2025-12-15 164205.png
 
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Svet said:
From my opinion not perfect M.2 physical installation is caused this.
Re-seat the M.2 drive physically.
Tip: When you install the M.2 drive in this bracket and push it down,
before use screw to secure the drive:
After pressing it down keep pressing strong (but not too strong) with a finger from one side of the corner vertically in the direction toward the pins
and while keep pressing install the screw, then release it.
For example: [blue = direction force to be pressed], [orange = which corner to keep constant pressing with finger until the screw is set]

View attachment 208217
Click to expand...
Attached my CrystalDiskMark.

I have seated it again and even installed into GPU x16 slot and it still showed me around 4GB/s.
One thing though is that I did not install the heatsink at all.
 

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artemii19915a902e5 said:
This one
www.glotrends-store.com

PA09-HS10 M.2 NVMe to PCIe 4.0 X4 Adapter with M.2 Heatsink for M.2 NVMe SSD

M.2 NVMe to PCIe X4 Adapter Support PCIe 4.0/3.0 SSD Support 2280/2260/2240/2230 form factor Come with M.2 heatsink kits (22x70x10mm aluminum body) Pre-installed 12cm regular-profile bracketm, and come with 8cm low-profile bracket
www.glotrends-store.com www.glotrends-store.com
Click to expand...

Not this, this is just the card and bracket.
I'm asking for M.2 Disk that you are trying to install there.

artemii19915a902e5 said:
I have seated it again
Click to expand...

Try again while put a force from a other corner, you can do push either left or right direction..
It may needs multiple attempts until starts working correctly from my such experience.

Also you can do:
Try put a different M.2 drive in this card/bracket and check if will have the same issue.
Or/and test this particular M.2 drive directly on the mainboard slot.
Those will help to point to the issue more precisely.
 
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artemii19915a902e5 said:
All my SSDs are the same model in other slots (aside Gen 5) and the benchmark showed around 7GB/s for all of them.
Click to expand...
artemii19915a902e5 said:
I have installed WD SN850X 4TB there. I have four of them (all the same 4TB drives) and other three I have installed into M.2_2, 2_3, 2_4.
M.2_1 has Samsung 9100 PRO 2TB.
Click to expand...

Try with the Samsung one.
But more important, try with another adapter. ;)
 
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After experimenting with other SSD and adapter - https://www.amazon.nl/dp/B094YBFZWV?ref=ppx_yo2ov_dt_b_fed_asin_title - I got the same results.

I put SSD from the adapter into one of the motherboard slots (M2_3) and it showed in the CrystalDiskMark around 7GB/s which is in line with previously used SSD. I put the previously used in M2_3 SSD into the PCI adapter and it showed the same 4GB/s (despite showing around 7GB/s in M2_3 slot before). I did not try with Samsung one as it is my Windows OS drive (don't want to risk it).

The hilarious part though is that due to the PCI power cable being under the slot, I can't use anything that has a heatsink as the cable prevents that
 

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So you tried with 2 different adapters and in both x16 and x4 slots and you get the same around 4GB/s.
But you tried with the same WD SN850X 4TB type of drive.
I told you to try with the Samsung one.

In any case, be aware of a few things:
1) the Sequential R/W are not realistic operations. In the real workflows (apps and games both) the real speed is 2-3 times slower (1-3GB/s, see the Random 4K results)
2) the theoretical PCIe 4.0 x4 speed is around 7000MB/s and the 3.0 one is around 3500MB/s.
Anything faster than 3500MB/s goes for PCIe 4.0 and this is your case.
So you don't have PCIe 3.0 speeds. You have low PCIe 4.0 speeds ;)
It might be due to incompatibilities of that WD SN850X with PCIe adapters.
 
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RemusM said:
So you tried with 2 different adapters and in both x16 and x4 slots and you get the same around 4GB/s.
But you tried with the same WD SN850X 4TB type of drive.
I told you to try with the Samsung one.

In any case, be aware of a few things:
1) the Sequential R/W are not realistic operations. In the real workflows (apps and games both) the real speed is 2-3 times slower (1-3GB/s, see the Random 4K results)
2) the theoretical PCIe 4.0 x4 speed is around 7000MB/s and the 3.0 one is around 3500MB/s.
Anything faster than 3500MB/s goes for PCIe 4.0 and this is your case.
So you don't have PCIe 3.0 speeds. You have low PCIe 4.0 speeds ;)
It might be due to incompatibilities of that WD SN850X with PCIe adapters.
Click to expand...

Well it seems like the problem is indeed with SN850X incompatibility. I put Samsung 9100 Pro there and got 7GB/s. And I put my another SSD from a different PC - Lexar NM990 and also got 7GB/s. Granted both of them are Gen 5 and not Gen 4, so unless the adapter arbitrary cuts the bandwidth in half, it is probably due to SN850X indeed but I don't have other Gen 4 SSDs to check so I will keep it that way. Bummer though.
 
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artemii19915a902e5 said:
Well it seems like the problem is indeed with SN850X incompatibility. I put Samsung 9100 Pro there and got 7GB/s. And I put my another SSD from a different PC - Lexar NM990 and also got 7GB/s.
Click to expand...

And the incompatibility has nothing to do with the motherboard.
That's because you get the same 4GB/s with the adapter in the x16 slot.
And that one is connected directly to CPU.
 
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RemusM said:
And the incompatibility has nothing to do with the motherboard.
That's because you get the same 4GB/s with the adapter in the x16 slot.
And that one is connected directly to CPU.
Click to expand...
I went to WD dashboard and indeed it showed me this for my SSD drive in PCIE adapter, which matches with PCIE4 x2
 

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