AM4/x570 Motherboard and PCIE Lanes

[MaximuT]

Hi there. 

I am looking for some knowledge. 

 

Currently I'm having Following confuguration:

AMX 3950X

Gigabyte x570 Aorus Elite

PowerColor 5600X

Seasonic prime 750 (or 850? Dont remember)

ADATA XPG sx8200 1 GB m2 SSD

Samsung EVO 120 GB (system)

Samsung PRO 512 GB

4 TB Seagete Baracuda HDD

1 TB WD HDD

All in Lian Li Dynamic XL case

 

So, i want to upgrade this system, but RTX 3000 series either out of stock or prices are too high. Same for Radeon. But I'm optimist and will wait till times when GPU will be available.

At this moment I need to upgrade my monitors, so money will go first for it. But still i need to change system SSD. 120 GB is not enough now. Yesteday installed DaVinci Resolved and now i have 2GBs of free space. Chrome with OPERA will not be happy. 

 

And know i start to pounder.

I have 2xM2 slots. One of them  should be on PCIe 4.0 lanes. 6 Sata connectors on MB. And i need to upgrade all this system

 

Currently i want to install additional m2 SSD with high capacity to PCI 4.0 m2 slot, replace system SATA SSD to 500GB+ Option. And replace 1 TB HDD, or just increase HDD capacity by adding 2 additonal sata HDD.

 

How many devices am i able to install?  And as i know on some MBs Sata slots shotdown when m2. slots are used. 

 

An also, as I undestand, if i use all m2. and sata slots, my GPU will use not 16, but 8 lines of PCIe, am i right? If it is so, aprocimately how many performance I will lose (in percentage)? 

[Electronics Wizardy]

Both m.2s will be pcie gen 4, so put the second ssd in there.

 

The second m.2 won't disable any sata ports, so you can still use all sata ports.

 

3 minutes ago, MaximuT said:

An also, as I undestand, if i use all m2. and sata slots, my GPU will use not 16, but 8 lines of PCIe, am i right? If it is so, aprocimately how many performance I will lose (in percentage)? 

Gpu will always run a x16, the other slots all rum from the chipset lanes.

[Archer42]

Best place to get this info from is motherboard manual, or motherboard specs on official site.

This may differ from motherboard to motherboard depending on manufacturer's decisions, even with the same chipset/platform.

[mariushm]

cpu creates 24 pci-e lanes:

* 16 go to video card slot (or 2 x8 slots, if motherboard designs it that way)

* 4 go to first m.2 connector (or other things if motherboard maker designs it like that, majority keep the 4 lanes for m.2)

* 4 go to chipset.

 

Chipset takes these 4 pci-e lanes and creates a bunch of pci-e lanes. Some are used inside the chipset to connect usb controllers, sata controller, other things, and finally, the chipset creates 8 pci-e lanes which the motherboard maker can group as they want into slots or other things... a lot of motherboard makers will arrange the 8 pci-e lanes as :

* 4 to a pci-e x16 slot (but only 4 pci-e lanes actually in slot)

* 4 to a 2nd m.2 connector (sometimes going down to pci-e x2 if some pci-e x1 slots are used)

* 2 lanes going to 1-2 pci-e x1 slots (disabled if a 2nd m.2 nvme SSD is installed, and you don't choose to limit the m.2 to pci-e x2 in bios)

 

So what you plug in m.2 connectors should not affect the number of pci-e lanes available to the video card. There are maybe a handful of motherboards which are on purpose designed differently, but those are the exception. Your motherboard is "normal"

[Archer42]

5 minutes ago, mariushm said:

the chipset creates 8 pci-e lanes which the motherboard maker can group as they want into slots or other things

IIRC x570 has 16 lanes available.

[MaximuT]

1 hour ago, mariushm said:

cpu creates 24 pci-e lanes:

* 16 go to video card slot (or 2 x8 slots, if motherboard designs it that way)

* 4 go to first m.2 connector (or other things if motherboard maker designs it like that, majority keep the 4 lanes for m.2)

* 4 go to chipset.

 

Chipset takes these 4 pci-e lanes and creates a bunch of pci-e lanes. Some are used inside the chipset to connect usb controllers, sata controller, other things, and finally, the chipset creates 8 pci-e lanes which the motherboard maker can group as they want into slots or other things... a lot of motherboard makers will arrange the 8 pci-e lanes as :

So you mean, that in total i will have not 24, but 28 lines?

 

1 hour ago, Archer42 said:

Best place to get this info from is motherboard manual, or motherboard specs on official site.

This may differ from motherboard to motherboard depending on manufacturer's decisions, even with the same chipset/platform.

Yes, you are right. I had that little "book" that i read several times, but for some reason i forgot everything on this (perhaps due to Cumberbatch's Holms technique to delete not relevant data), and suddenly I called in mind that on LTT there good people that could help..

1 hour ago, Electronics Wizardy said:

Both m.2s will be pcie gen 4, so put the second ssd in there.

 

The second m.2 won't disable any sata ports, so you can still use all sata ports.

 

Gpu will always run a x16, the other slots all rum from the chipset lanes.

Thank you very much. 

[mariushm]

22 minutes ago, MaximuT said:

So you mean, that in total i will have not 24, but 28 lines?

It depends on motherboard manufacturer, but yes, most of the time yes.

 

See the pictures below :

 

How CPU connects to chipset and you can see the separation between cpu pci-e lanes and chipset pci-e lanes.

 

 

Motherboard manufacturer can chose to sacrifice sata ports for more pci-e lanes or for extra m.2 connectors, but majority will use the "default" of 2 m.2 connectors and 1 pci-e x4 slot (in x16 physical slot) and lots of sata ports

 

 

I may have been wrong .... it's 12 pci-e lanes from chipset ... but I think only 8 can go outside to slots or onboard devices

 

 

 

[FirefoxMetzger]

The (real-world) performance difference between your setups is likely negligible (we are talking <5%), so it's really a micro-optimization and you probably shouldn't loose sleep over it. You are correct that there will be some difference, but unless you are trying to get some OC high-score on a benchmark of your choice it won't actually affect you.

 

Your GPU will get a full x16 lane to the system's root complex (aka northbridge, afaik sits inside the CPU for the Ryzen family) irrespective of your storage setup. The M2A socket on your board also directly connects to the root complex with a x4 PCIe lane. Your Chip (x570) also has an x4 PCIe connection to the root complex. This makes up the 24 PCIe lanes that your root complex offers.

 

Every other PCIe device will connect to the root complex through the chipset (aka southbridge). So it doesn't matter if you use the M2B socket, the x16 socket, or the x1 sockets, they can at most offer x4 PCIe, since this is the fastest the chipset can talk to the root complex. If you connect multiple devices, they will share those lanes, which can make your effective speed slower than x4 whenever multiple devices want to communicate with something in the root complex at the same time; it's the same thing that happens when you have a lot of devices in the same (wifi) network. For these devices, you also incur a cost from having the chipset mediate the communication, which makes your effective speed slower than x4. How exactly this plays out is VERY application dependent, and nobody here can tell you. You'll have to benchmark and optimize.

 

There is some cool stuff in the pipes at Nvidia and Microsoft called GPUdirect Storage (Nvidia, for servers), RTX I/O (Nvidia, for consumers), and DirectStorage (Microsoft), which allows programs to better utilize concurrency or even load data directly from storage into GPU memory. This might be limited to devices connected directly to the root complex or it may not be, but my information on that is really vague, so I can't comment on this any further.

 

The bottom line is to take your biggest M2 NVMe card and put it into your M2A socket, and connect all other cards in any way you fancy. Make sure your OS uses the device connected to M2A for its swap/pagefile, and you're good to go.

[MaximuT]

Thanks guys for your responces.

I have additional question. 
Which will be better, to install m2 SSD and copy my windows to it? Or it does not matter for system on what drive system is intalled?
FirefoxMetzger's message got me thinking on it. 

[Archer42]

2 minutes ago, MaximuT said:

Which will be better, to install m2 SSD and copy my windows to it? Or it does not matter for system on what drive system is intalled?

It does not matter.

m2/nvme only benefits very specific workloads, os is not one of them.

[MaximuT]

1 minute ago, Archer42 said:

m2/nvme only benefits very specific workloads, os is not one of them.

Ok. 
So the situation is next.

I have a lot of raw family VHS videotapes which I'm converting to Digital hardware. And i need to make a lot of adjustmests and Editing. An ordinary Sony Vegas was enough for me for these works, but since during the quarantine I somehow fired up with the desire to do video editing and drawing, and I also play videogames and make footages that I also want to share with the guys. In general, I downloaded DaVinci Resolve and now I am studying it. And I thought:
- It's clear with games, I just installed it, and it will be installed on the disk that you indicated, well, it also partially installs on the disk with the system (C :). But what about such programs as DaVinci, do they also need to be installed on the disk with the system, or can they be put on a separate one (second SSD)?

- Also, should I store footage on SSD or HDD will be enough? At the moment I am uploading all the raw video to the hard disk with 5400 rpm.

- What about the work itself and what about  final project, also save on the SSD?

[Archer42]

56 minutes ago, MaximuT said:

t's clear with games, I just installed it, and it will be installed on the disk that you indicated, well, it also partially installs on the disk with the system (C :). But what about such programs as DaVinci, do they also need to be installed on the disk with the system, or can they be put on a separate one (second SSD)?

Software can be installed anywhere but then it does not really matter. Might as well install it on system drive to make thing less complicated if/when you want to replace secondary storage.

 

58 minutes ago, MaximuT said:

- Also, should I store footage on SSD or HDD will be enough? At the moment I am uploading all the raw video to the hard disk with 5400 rpm.

- What about the work itself and what about  final project, also save on the SSD?

HDD will work, SSD will be faster. As usual. IMO the most logical solution is to keep what you are working with on SSD and use HDD for storage.

 

One important thing when working with video and other large stuff can be temporary folder location. Both for os and for whatever software you are using. Might be a good idea to move it somewhere from system drive.

[MaximuT]

12 minutes ago, Archer42 said:

One important thing when working with video and other large stuff can be temporary folder location. Both for os and for whatever software you are using. Might be a good idea to move it somewhere from system drive.

Hmmm... how to "Move from System drive" temporary folders? Am i right, that we are talking about files in AppData and Temp folders?