# ASUS X370 Pro - M.2 Slot in SATA mode, will it disable "normal" SATA ports?



## Wavetrex (Jan 27, 2019)

So I have this motherboard with a Ryzen 1700:

https://www.asus.com/us/Motherboards/PRIME-X370-PRO/

It's being used as a file server for large files (4K video) and it works great.
All 8 SATA ports are being connected to devices, 7 to harddisks and one boot SATA SSD.

I was thinking to use a small M.2 drive to boot the OS, and connect another harddisk to the 8th SATA port.
In the manual it says the slot supports both NVMe and SATA modes, but it doesn't specify what happens when you actually connect one.

Will it turn off (some) existing SATA ports ? Or is M.2 using another controller ?
or
If I connect an NVMe drive, will other PCI-e stuff will be disabled (Like front USB 3.1 Gen-2 connector)

Anyone with experience with this board?
Thanks !


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## hellrazor (Jan 27, 2019)

Putting the M.2 slot in SATA mode makes the drive in it run slower.


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## Bo$$ (Jan 27, 2019)

It won't disable the SATA ports


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## Wavetrex (Jan 27, 2019)

Bo$$ said:


> It won't disable the SATA ports


So where is it connected then ?
The X370 PCH only offers 8 SATA ports...

---
I might have found the mystery SATA controller...






Apparently AM4 socket itself has a built-in SATA controller !

And I'm seeing this extra device in Windows, in "connections" mode:




Good job AMD !
I think can safely buy a cheapo SATA M.2 drive and relocate that Samsung 850 to other purposes.


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## Bo$$ (Jan 27, 2019)

the NVME slot will have it's own PCI-e lanes. The SATA/NVME mode isn't going to change where the PCI-e lane comes from


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## Wavetrex (Jan 27, 2019)

To conclude: The reason I asked the question in the first place is because I previously found plenty of forum posts where people were complaining that once they installed an M.2 drive ... one or more of their harddisks stopped functioning.

Well, apparently what all those people had in common is that *they were on Intel mainstream platform. (Sk 115x)*, which does not have those extra PCI-e lanes on the CPU, and also doesn't have any integrated SATA controller.
So what the motherboard manufacturers did... they routed the same SATA lines from the PCH (South Bridge) to both the ports on the side of the motherboard and to the M.2 slot.

BUT, it seems with AM4 that is not the case, as _there is one SATA controller straight IN THE CPU_. Which I find pretty amazing !
It appears as a separate device, linked to a different PCI-to-PCI bridge than the primary AHCI controller ( with 8 ports in case of X370)



Bo$$ said:


> the NVME slot will have it's own PCI-e lanes. The SATA/NVME mode isn't going to change where the PCI-e lane comes from


That is indeed correct Boss !
24 PCI-e lanes on AM4 ( (8+8) + 4 + 4 ), and those 4 extra can work with SATA based signaling (2x2) - See the left side, middle of the image:



... while only 20 on 1151, and no extra controller, has to rely completely on the PCH for I/O



P4-630 said:


> Well if I use M.2 SATA on my motherboard it will disable one SATA port, I found this in the motherboard manual.
> Buy M.2 NVMe.


Where exactly ? Because I did read that manual top to bottom before coming here.

Anyway, not important, I think I found enough information and will try it in practice in a week or so.


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## Wavetrex (Jan 27, 2019)

Wavetrex said:


> So I have this motherboard with a *Ryzen 1700*:
> asus ... PRIME-*X370*-PRO
> ...
> Anyone with experience with *this board*?





P4-630 said:


> Here it is, from my Asus Z170 Pro Gaming motherboard


Why would you give an "advice" on a completely different platform designed for a completely different CPU from Intel 
Especially when my question was addressed specifically about that X370 board ...


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## Wavetrex (Jan 27, 2019)

P4-630 said:


> I thought M.2 in SATA mode will disable a SATA port.


Me too.
Because I kept finding confusing posts like yours, about random Intel-based boards, when I was clearly looking for AM4, AMD, X370, freeking A.M.D., NOT bloody Intel !!



P4-630 said:


> M.2 NVMe isn't expensive anymore so why not go with that.


Because any amount is bigger than zero.


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## Voluman (Jan 28, 2019)

It varies by chipset and manufacturers. B series boards usually disable sata port(s) if m2 in sata mode used. Sometimes even with pcie mode too.
But X series chipset should not be behave like that. If your board is Prime X370 Pro you probably can use sata or nvme m2 drive, because its manual say nothing against it, so you can use 8 sata and 1 m2 drive.


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## EarthDog (Jan 28, 2019)

Read your mobo manual. It will tell you exactly which ports, if any, are disabled when using a sata based m.2 drive. If it does show any, than none are disabled. You can also call/chat/email tech support as well. 



Wavetrex said:


> Well, apparently what all those people had in common is that *they were on Intel mainstream platform. (Sk 115x)*, which does not have those extra PCI-e lanes on the CPU, and also doesn't have any integrated SATA controller.
> So what the motherboard manufacturers did... they routed the same SATA lines from the PCH (South Bridge) to both the ports on the side of the motherboard and to the M.2 slot.


intel mainstream has extra pcie lanes...they also have integrated sata controller.


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## TheLostSwede (Jan 28, 2019)

EarthDog said:


> Read your mobo manual. It will tell you exactly which ports, if any, are disabled when using a sata based m.2 drive. If it does show any, than none are disabled. You can also call/chat/email tech support as well.
> 
> intel mainstream has extra pcie lanes...they also have integrated sata controller.



Actually, the manual doesn't mention it, but at least one port should be disabled, since two of the eight ports are from the CPU and one of them would be routed to the M.2 slot and is as such shared. I use an NVMe SSD, so I don't have that problem with my board.

The chipset diagram up top is slightly flawed, as it doesn't show that two of the SATA ports comes from the CPU/SoC.
This is a better diagram - https://rog.asus.com/articles/techn...platform-and-its-x370-b350-and-a320-chipsets/


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## EarthDog (Jan 28, 2019)

TheLostSwede said:


> Actually, the manual doesn't mention it, but at least one port should be disabled, since two of the eight ports are from the CPU and one of them would be routed to the M.2 slot and is as such shared. I use an NVMe SSD, so I don't have that problem with my board.
> 
> The chipset diagram up top is slightly flawed, as it doesn't show that two of the SATA ports comes from the CPU/SoC.



This would be the first time (I saw) a manual doesnt mention it! Wow!

But in looking at the chipset diagram, what you are saying isnt true? Its cpu connected while sata is all sourced from pch?


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## TheLostSwede (Jan 28, 2019)

EarthDog said:


> This would be the first time (I saw) a manual doesnt mention it! Wow!
> 
> But in looking at the chipset diagram, what you are saying isnt true? Its cpu connected while sata is all sourced from pch?



Six of the SATA ports are from the chipset, two are from the CPU. However, if you use an M.2 NVMe drive, the two SATA ports from the CPU are disabled.
If you use an M.2 SATA drive, one of the SATA ports from the CPU would be used, so one of the ports on the motherboard would be disabled.
And yes, it's really weird Asus doesn't mention this in the manual.


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## EarthDog (Jan 28, 2019)

Is there a chipset diagram explaining this? I'm not an amd guy but all I ran across are like this?


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## TheLostSwede (Jan 28, 2019)

EarthDog said:


> Is there a chipset diagram explaining this? I'm not an amd guy but all I ran across are like this?



You too lazy to click on the link above? https://rog.asus.com/articles/techn...platform-and-its-x370-b350-and-a320-chipsets/

This is also why most boards only have six SATA ports, rather than eight, so there's no confusion I guess.
However, you don't lose two ports, like you would on an Intel board.


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## EarthDog (Jan 28, 2019)

TheLostSwede said:


> You too lazy to click on the link above? https://rog.asus.com/articles/techn...platform-and-its-x370-b350-and-a320-chipsets/
> 
> This is also why most boards only have six SATA ports, rather than eight, so there's no confusion I guess.
> However, you don't lose two ports, like you would on an Intel board.



The one you edited in after I responded and my quote never caught? No reason to be a jerk about it...wtf....you edited that in late and being a butt to me about it??

...and thank you.


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## Deleted member 67555 (Jan 28, 2019)

So basically he can only run 6 SATA drives  and 1 NVMe in NVMe drive  or 8 SATA drives all in SATA.
Sounds like an Intel board problem .. I completely get the confusion here.


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## Wavetrex (Jan 31, 2019)

TheLostSwede said:


> Six of the SATA ports are from the chipset, two are from the CPU. However, if you use an M.2 NVMe drive, the two SATA ports from the CPU are disabled.


That is not what I'm seeing in the Windows Device Manager.

Maybe what you say applies for B350, but not for X370.

As seen in my screenshot it's very clear that 8 ACTIVE SATA connections 7 HDD + 1 SSD are all linked to the same AHCI 1.0 Serial ATA Controller which has the ID:
Vendor 1022 Device 43B5 (PCI bus 1, device 0, function 1)
https://devicehunt.com/view/type/pci/vendor/1022/device/43B5 - X370 Series Chipset SATA Controller

Again, I repeat, I have 8 storage devices ALL linked to this X370 SATA Controller, which means the information posted on the link above from ASUS is plain wrong. (It says only 6 SATA ports for X370)

The "other" port which is not connected anywhere right now is on a completely different PCI-to-PCI bridge (I'm guessing INSIDE the Ryzen 7 CPU), and is named AMD SATA Controller, with the ID:
Vendor 1022 Device 7901 (PCI bus 11, device 0, function 2)
https://devicehunt.com/view/type/pci/vendor/1022/device/7901 - *FCH SATA Controller* [AHCI mode]

It's quite clear that these are two different controllers, and by looking at that schematic, 7901 is the dual-port SATA controller INSIDE the CPU.
(And on my particular board I have a strong feeling it's linked directly to that M.2 slot - unfortunately I cannot shut down the computer and take out the board to follow the traces), but given the fact that it's right under the CPU, there's a very strong chance that is the case:





*Will test this in about a week* when my M.2 SATA drive arrives (inside a laptop actually, which I'm going to extract and replace with a properly sized NVMe drive).

A few more screenshots:







If I had any doubts before, they are clearly gone now.
There's 9 independent SATA ports on this system ! 8 + 1

~~~
Alternatively, this drive is soooo cheap for the size:
https://www.amazon.de/dp/B077SQ8J1V/

(It's actually cheaper than the normal 2.5" equivalent. Finally SSD's are truly affordable)


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## Wavetrex (Jul 14, 2019)

Digging this up as a followup, as I've bought a very cheapo boot drive for this computer, a Kingston low-end "dual-channel" 240GB





Ignore the blue "Covecube Virtual"... that's obvious... virtual.

The rest are obviously all SATA drives, 9 of them.
_The theory became practice !_

Anyone looking to build a cheapo *media* server for many and large files: X370 on boards with all 8 ports connected is the way, combined with an 2200G for example for CPU and GPU.
I specified "media" server because there are ways to do files-servers cheaper, but they don't have the necessary horsepower for video transcoding for multiple users at once (for example, PLEX)

~~~~
That being said... I've moved this PC as my main workstation+gaming, which is why it has two 1TB SSDs, in preparation for an incoming 3700x.

<-- See _System Specs_ for complete config.


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