SLI only using vram of one card

[Ekko84]

2 x Titan X in SLI and playing Witcher 3, Nvidia Inspector on whilst playing and monitoring Mem usage shows only the memory on GPU0 being used, the other one stays at 0MB usage.

Is this normal?

Notes:
- I know SLI doesn't double the amount of VRAM available, but I thought the other card still used it's memory...

- I haven't had a chance to try any other games yet, but even when not running games, I can see Mem usage sitting at 860MB for GPU0 and 0MB for GPU1.

- The GPU Usage for BOTH cards does go up during games, as does the temperature.

 

[KKAW]

2 x Titan X in SLI and playing Witcher 3, Nvidia Inspector on whilst playing and monitoring Mem usage shows only the memory on GPU0 being used, the other one stays at 0MB usage.

Is this normal?

Notes:
- I know SLI doesn't double the amount of VRAM available, but I thought the other card still used it's memory...

- I haven't had a chance to try any other games yet, but even when not running games, I can see Mem usage sitting at 860MB for GPU0 and 0MB for GPU1.

- The GPU Usage for BOTH cards does go up during games, as does the temperature.

Yes, it's normal.

 

[Ekko84]

That's a relief. Can I ask how you know this is normal?

As a side question, why doesn't it use the vram of the other card?

 

[KKAW]

That's a relief. Can I ask how you know this is normal?

As a side question, why doesn't it use the vram of the other card?

http://www.overclock.net/t/1365868/please-does-vram-stack-in-sli-crossfire-or-not
http://www.techpowerup.com/forums/threads/why-cant-crossfire-or-sli-use-the-sum-of-vram-from-all-gpus.167301/

 

[atomicWAR]

2 x Titan X in SLI and playing Witcher 3, Nvidia Inspector on whilst playing and monitoring Mem usage shows only the memory on GPU0 being used, the other one stays at 0MB usage.

Is this normal?

Notes:
- I know SLI doesn't double the amount of VRAM available, but I thought the other card still used it's memory...

- I haven't had a chance to try any other games yet, but even when not running games, I can see Mem usage sitting at 860MB for GPU0 and 0MB for GPU1.

- The GPU Usage for BOTH cards does go up during games, as does the temperature.

Yes, it's normal.

umm no and if you read the links he posted all the way through they say the same thing. the graphics rendering information is mirrored on both sets of ram. The ram is not stacked (ie doubling the memory) that is true but gpu 0 and gpu 1 should both be using there respective ram pools to render their scenes. when I run witcher 3 both sets of ram are used not just GPU 0. My question to Ekko is is he sure SLI is enabled, functioning properly and have an SLI bridge properly installed.

 

[Groza Adrian]

Since launching the game puts pressure on both GPUs I would presume that SLI is active,enabled and configured correctly.Regarding Nvidia Inspector I would say it's most likely a bug in the sotfware/driver report and that you should not be worried about it.If you want to measure Memory load you can also use 3rd party tools such as GPUZ(it supports multiple gpus) to see what's what.
If the Inspector would have been right you would have seen a tremendous performance handicap since the GPU that does not use its own memory would have to process textures that are (technically) far away from the core (inducing latency),it would also compete with the GPU on which the Vram is installed but worse,it would have a tremendous bandwidth handicap since it would transfer data either via Pci-e or the Sli bridge(or both) which are significantly slower than the Titan's internal bus capabilities.

 

[Ekko84]

Yup, seems it's a bug with Nvidia Inspector, GPUZ displays both GPUs as using memory. Thanks for your help.