Order of GPUs / decide which GPU is used to build scene

Renomista

Hi is there any way to control the order of the GPUs and/or which GPU is used to build the scene?

This is based on the following Problem:

I have 3 GPU Cards in my  machine

2 x 970s ( lots of CUDA cores 4/3,5GB)
1 x 730 ( few CUDA cores 4GB)

(Monitors are connected to a non NVIDIA onboard GPU)

they are detected (consistently) as

[0] 970

[1] 730

[2] 970

DS seems always to use [0] as the device to build the scene what seem to use up some of the RAM

When I render Scenes that are allready near the RAM limit for the 970s i get Warnings in the log for device [0] and in the final statistic this device does a lot less iterations than the other 970. This significantly increase Render Time (nearly doubles it)

Is there a way to bring DS to use the 730 to build the scene. 1) it has more usable RAM 2) if i loose iterations on it it would have a much smaller impact on the render time.

(4.9 on a Win10 64 bit machine)

chickenman

Not sure but it could be related to the order in which the cards are placed on the motherboard. You would have to look at eh motherboard specs if you have one and look at theorder of the cards themselves and where they are placed.

Renomista

Interesting Thought

Physically they are set 970, 970, gap, 730

Have to look up the MB Specs and see how they are listend in BIOS

mjc1016

Renomista said:

Interesting Thought

Physically they are set 970, 970, gap, 730

Have to look up the MB Specs and see how they are listend in BIOS

I'm guessing that the layout of the slots on the motherboard is where you'll find the answer.

SpottedKitty

Renomista said:

Is there a way to bring DS to use the 730 to build the scene.

Are you sure you're not seeing the part of your cards that's used to build and display the actual Windows screen (including the D|S window)? This isn't quite constant, it goes up and down a bit as your running programs go through their jobs.

mjc1016

 

SpottedKitty said:

Renomista said:

Is there a way to bring DS to use the 730 to build the scene.

Are you sure you're not seeing the part of your cards that's used to build and display the actual Windows screen (including the D|S window)? This isn't quite constant, it goes up and down a bit as your running programs go through their jobs.

It was mentioned:

Renomista said:

 

(Monitors are connected to a non NVIDIA onboard GPU)

So I'm not sure that would matter?  If the onboard is being used for the OS/display it shouldn't have any impact, right?

DAZ_Spooky

Motherboards do vary, especially when you have multiple GPU's. In general the first GPU is the one closest to the CPU but after that it is a guess, at best. 

 

Note that the GTX 970 has 4GB, half a GB is slower Ram, which matters for gaming, but not for Iray.  

Renomista

Thanks DAZ_Spooky for confirming the 4gb usage in the 970. i assumed this allready but was never sure.

moving the 730 to the first slot is no option unfortunatly b/c of a badly designed passive cooler on it :-(

Would choosing wich card is used for building a scene be a possible feature or does IRay not support this?

DAZ_Spooky

Renomista said:

Thanks DAZ_Spooky for confirming the 4gb usage in the 970. i assumed this allready but was never sure.

moving the 730 to the first slot is no option unfortunatly b/c of a badly designed passive cooler on it :-(

Would choosing wich card is used for building a scene be a possible feature or does IRay not support this?

Iray doesn't build scenes. Which card is used to drive the monitors while you build a scene depends on which card your monitor(s) is plugged into. If you are using the Iray viewport then you can choose which cards are used to render on the advanced tab of the Render settings pane. 

Tobor

Renomista said:

(Monitors are connected to a non NVIDIA onboard GPU)

It certainly does sounds like the first card is using some VRAM for display. Review your settings for a phantom monitor. A misconfiguration in Windows can result in a graphics card using its VRAM for holding display memory even if no monitor is connected to it. 

If you aren't already, use a utility like GPU-Z to actively monitor the VRAM and other sensor data of each of your cards. Note the at-idle VRAM use of each of your cards. For a card not used to hold display data, the VRAM use should be paltry -- on the order of under 20-50 MB or so.

As noted above, the scene database is created by the CPU in system RAM. You can see this happening by opening Task Manager, and viewing Processes. Keep an eye on DAZStudio.exe. Start a render and even before there are renderpass interations the RAM starts building up. This is the scene database being built. Let it render, then cancel, but keep the render window open. Wait for the RAM usage to stablize a bit, and then close the window. Note the significant reduction in memory allocation to D|S.

Renomista

DAZ_Spooky said:

Renomista said:

Thanks DAZ_Spooky for confirming the 4gb usage in the 970. i assumed this allready but was never sure.

moving the 730 to the first slot is no option unfortunatly b/c of a badly designed passive cooler on it :-(

Would choosing wich card is used for building a scene be a possible feature or does IRay not support this?

Iray doesn't build scenes. Which card is used to drive the monitors while you build a scene depends on which card your monitor(s) is plugged into. If you are using the Iray viewport then you can choose which cards are used to render on the advanced tab of the Render settings pane. 

It's not about monitors.

 

It is about the following Log entry:

Iray INFO - module:category(IRAY:RENDER):   1.4   IRAY   rend info : Using device 0 to build data for host

 

mjc1016

On some motherboards Device 0 is the onboard...

Tobor

I don't believe the "data for host" refers to the scene database. If it's on, try turning OptiX off, to see if that helps.