Need help with understanding motherboard's spec on dual gpu

[zua93117]

Hey all,

 

I have a Ryzen 3rd Gen CPU with MSI  B450 Gaming Plus Max that could support two graphics card.

I would like to run to cards only because I would like to color calibrate two monitors.

Because as far as I know, AMD's radeon series has one LUT and Firepro has two -  I suspect the same of Nvidia.

 

The two cards will not be linked.

One very good GPU will do all the work (configured via Nvidia's control panel) while the other old and "weak" one will just be there for the second display.

 

My motherboards specs regarding mutli-gpu is shown in the picture.

Does this mean that my main card that is in slot 1 will drop down to 3.0x8 or 3.0x4 as soon as I put a card in slot4, or will the card in slot one maintain 3.0x16 speed?

[minibois]

12 minutes ago, zua93117 said:

Does this mean that my main card that is in slot 1 will drop down to 3.0x8 or 3.0x4 as soon as I put a card in slot4, or will the card in slot one maintain 3.0x16 speed?

Slot 1 will always be PCIE 3.0 x16 (on a Ryzen 3rd gen, excluding 3200G and 3400G).

M.2 will always be PCIE 3.0 x4 (on any Ryzen CPU)

 

The other PCIE slots are receiving lanes from the chipset, rather than CPU. Slot 4 is working in PCIE 2.0 x4 speeds (that's 2GB/s if I remember correctly and could bottleneck a modern videocard, depending on your purposes).

 

Could you link the model and make of your motherboard so I can verify what I just said above real quick?

[zua93117]

14 minutes ago, minibois said:

Slot 1 will always be PCIE 3.0 x16 (on a Ryzen 3rd gen, excluding 3200G and 3400G).

M.2 will always be PCIE 3.0 x4 (on any Ryzen CPU)

 

The other PCIE slots are receiving lanes from the chipset, rather than CPU. Slot 4 is working in PCIE 2.0 x4 speeds (that's 2GB/s if I remember correctly and could bottleneck a modern videocard, depending on your purposes).

 

Could you link the model and make of your motherboard so I can verify what I just said above real quick?

Thank you!

I'll be good as long as slot 1 get full speed.

 

The card that'll go in slot 4 could be either a gtx 660 or 640. it will only be used to connect to another display and do nothing else, so i'll probably go with 640 to decrease power draw. I'm really using it for the extra LUT anyway.

 

I don't have anything in slot 2, 3, 5 so it'll rung at 2.0x4 speed.

 

Here's the link to motherboard specs

 

Thanks again!

[mariushm]

The first pci-e x16 slot  has 16 pci-e lanes or 8 pci-e lanes depending on CPU ( cpus with integrated graphics have only 8 pci-e lanes going to the slot)

The m.2 connector closest to the cpu socket receives 4 pci-e lanes from the cpu

 

The other pci-e slots receive pci-e lanes from the chipset. B450 chipset creates 6 pci-e 2.0 lanes which the motherboard designer allocated to pci-e slots or additional m.2 connectors.

 

You have a second pci-e x16 (physically) but which electrically is only x4 and it's pci-e 2.0 (so only 500 MB/s instead of ~970 MB/s for pci-e 3.0)

 

If you want the slot to have 4 pci-e lanes, all but one pci-e x1 slot must remain empty, otherwise the motherboard will downgrade the 2nd pci-e slot to pci-e x1.

That's what that chart means   pci-e x4  + pcie_e6 x1  = 5 pci-e lanes

If you use any other pci-e x1 besides pcie_e6, the 2nd pci-e x16 slot may become x1

 

 

[mariushm]

Also i have to ask, your video card should have multiple monitor outputs .... why not just use another hdmi or displayport cable to connect the second monitor?

[minibois]

2 minutes ago, zua93117 said:

Thank you!

I'll be good as long as slot 1 get full speed.

The card that'll go in slot 4 could be either a gtx 660 or 640. it will only be used to connect to another display and do nothing else, so i'll probably go with 640 to decrease power draw. I'm really using it for the extra LUT anyway.

I don't have anything in slot 2, 3, 5 so it'll rung at 2.0x4 speed.

Here's the link to motherboard specs

Thanks again!

Can I assume you have a Ryzen 3000 CPU that is not a 3200G or 3400? If no, please state which you have and I can change the answer I give.

Because if you have a Ryzen 3000 that is not the 3200G or 3400G, this is how it will all connect:

Spoiler

The PCIE slots you are planning to use are on different parts of the system (the main slot is on CPU lanes, the other PCIE slots on chipset lanes, the M.2 on another part).

That means the slots will run at these speeds (when using those together, with the CPU listed above):
- PCIE slot 1 will run at PCIE 3.0 x16 speed

- PCIE slot 4 will run at PCIE 2.0 x4 speed (2GB/s)

- M.2 PCIE 3.0 x4 or SATA 6Gb/s (and sata ports 5 and 6 will be turned off when in use).

 

Of course I do have to - as did @mariushm - question your usage of multiple videocards.

I don't remember either if Nvidia had like a minimum requirements for PCI lanes on a GPU, or if that was just for SLI..

 

 

[zua93117]

Just now, mariushm said:

Also i have to ask, your video card should have multiple monitor outputs .... why not just use another hdmi or displayport cable to connect the second monitor?

Thanks for the clarification!

 

2 minutes ago, minibois said:

Can I assume you have a Ryzen 3000 CPU that is not a 3200G or 3400? If no, please state which you have and I can change the answer I give.

Because if you have a Ryzen 3000 that is not the 3200G or 3400G, this is how it will all connect:

  Reveal hidden contents

The PCIE slots you are planning to use are on different parts of the system (the main slot is on CPU lanes, the other PCIE slots on chipset lanes, the M.2 on another part).

That means the slots will run at these speeds (when using those together, with the CPU listed above):
- PCIE slot 1 will run at PCIE 3.0 x16 speed

- PCIE slot 4 will run at PCIE 2.0 x4 speed (2GB/s)

- M.2 PCIE 3.0 x4 or SATA 6Gb/s (and sata ports 5 and 6 will be turned off when in use).

 

Of course I do have to - as did @mariushm - question your usage of multiple videocards.

I don't remember either if Nvidia had like a minimum requirements for PCI lanes on a GPU, or if that was just for SLI..

 

 

Ah yes, I have a Ryzen 3700X.

 

Thank you for being of so much help^^

[zua93117]

22 minutes ago, mariushm said:

Also i have to ask, your video card should have multiple monitor outputs .... why not just use another hdmi or displayport cable to connect the second monitor?

@minibois

Because, if a video card only supports 1 LUT for the entire card (regardless of how many heads it has), the card can only effectively handle one color calibrated display.

 

Here's a quick blurb about LUT from Xrite - a color calibration company.

 

On that note, no matter how many ICC profiles Windows seems to allow users to attach to one graphics card, the graphics card can only support as many color calibrated displays as the number of LUT the card actually supports.

 

But I just found out that none of this matters anymore.... I just got off live chat with Nvidia.

So..apparently NONE of the Geforce cards support LUT. So I can't color calibrate even ONE monitor.

 

This hurts my soul......i'm hurting real bad. That rtx 2070 super (my main card I intend on using for graphic arts) wasn't cheap. lots of FFFFFF going on in my heart (apologies for twitch chat language)

 

That is SO MUCH WORSE than AMD if we're talking about LUT support, because the radeon line supports one and their firepro (competes against quadro) supports two --- source from AMD forum.

 

^The above thread is quite old, but the same answer is given in another thread about how many lut RX 480 supports.