Blackmagic Forum

Hi Guys,

Trying to test out Dual RX 480's in windows.
I have the Full Version of Resolve that came with my Production Camera.

If i have [Use Display GPU For Compute] ticked, Only one RX480 is showing in System.
If i un tick the box i get both GPU's showing but one is GUI only obviously.

On MacOS i have both showing when the box is ticked. It seems like a Windows issue??

Thanks for anyone willing to explain

BUMP


So i now have a 3rd GPU installed but only 1 RX 480 is able to be ued for compute.
As stated my Resolve is using a dongle because i can't open it without the dongle plugged in.

Make sure "Crossfire" is disabled in your GPU driver settings.

Aaron_Hayden wrote:Make sure "Crossfire" is disabled in your GPU driver settings.

I tried both Disabled and enabled and i get the same results.

What motherboard?

Adam Simmons wrote:What motherboard?

ASUS MAXIMUS VIII HERO Z170

Do you have any other cards in the system?

You do realise that 2 of the cards will be running at 8x and the third at a maximum of 4x which may slow all the cards down

Adam Simmons wrote:Do you have any other cards in the system?

You do realise that 2 of the cards will be running at 8x and the third at a maximum of 4x which may slow all the cards down

Yes i have a R7 270 for the GUI in the 4x slot.
That bandwidth is more than enough for compute, Even at 4k gaming a 4x slot only loses 4-10fps.
Also a Mac Pro is gen2 16x which is a gene 8x i saw no improvement on a Titan X in both machines.

Phillip Lakis wrote: Even at 4k gaming a 4x slot only loses 4-10fps.

What works for gaming isn't necessarily going to translate to Resolve.

You cpu/mobo combo doesn't have sufficient lanes to do what you want.

On that particular board, only the 16x/8x slots are routed directly to the cpu (the only GPU's that Resolve can see).

The R9 270 in the 4x slot is routed through the PCH/Southbridge chip first before continuing to the CPU. The PCH also handles all your SATA, USB, M.2 data to the CPU all within the same 4x lane constraint.

You need to leave these 4x lanes open for read/write media to your drives.

If your want an Intel 170 based motherboard capable of more lane capacity, you need to get one with a PLX chip. Like this one: https://www.asus.com/us/Motherboards/Z170-WS/

or

drop more $$$ and upgrade to X99 mobo's.

Aaron_Hayden wrote:

Phillip Lakis wrote: Even at 4k gaming a 4x slot only loses 4-10fps.

What works for gaming isn't necessarily going to translate to Resolve.

You cpu/mobo combo doesn't have sufficient lanes to do what you want.

On that particular board, only the 16x/8x slots are routed directly to the cpu (the only GPU's that Resolve can see).

The R9 270 in the 4x slot is routed through the PCH/Southbridge chip first before continuing to the CPU. The PCH also handles all your SATA, USB, M.2 data to the CPU all within the same 4x lane constraint.

You need to leave these 4x lanes open for read/write media to your drives.

If your want an Intel 170 based motherboard capable of more lane capacity, you need to get one with a PLX chip. Like this one: https://www.asus.com/us/Motherboards/Z170-WS/

or

drop more $$$ and upgrade to X99 mobo's.

Thanks for all the info.

Although we are WAY of topic.

This is not my WS, This is a test bench.
My problem lies in Resolve not recognising more that 1 GPU even though my system does, Actually every application except for Resolve.

Phillip Lakis wrote:My problem lies in Resolve not recognising more that 1 GPU even though my system does, Actually every application except for Resolve.

Phillip Lakis wrote:If i have [Use Display GPU For Compute] ticked, Only one RX480 is showing in System.
If i un tick the box i get both GPU's showing but one is GUI only obviously.

Right right right....

Try going into preferences and setting "Pre Allocated System Memory" to 4000 MB.

and remove the 270 in the 4x slot.