2 GTX 780

[dirtyjohn_lv]

SLI makes no difference, although Resolume no longer crashes with SLI turned on. Not sure that anyone besides game makers use SLI profiles. Do Cinema 4D or similar programs utilize SLI?

High frame rates above 60 are most likely caused by disabling stuff like ambient occlusion and vertical sync in GPU settings.


One thing I am curious about it is capture to GPU. Could we capture external sources direct to the second non-rendering GPU?

[Oaktown]

I hear you but the only difference is that using SLI or Crossfire creates a bridge between 2 GPUs so that they can behave as one and "all displays outputs are connected to the primary (master) card and outputs on the slave card(s) are disabled".

Also, I have not used SLI, just Crossfire so I don't know if there is a difference.

[dirtyjohn_lv]

Display outputs are NOT disabled in SLI, not sure how it works in AMD Crossfire. I used 6 outputs regularly, the 7th (during summer only) and 8th when needed. The combined calculations are only used if the software supports it as far as I know.

1 x control monitor
1 x 4mm led 1440x900
2 x 6mm led 864x480
1 x 8mm led 512x288
1 x 720p tricaster feed

Only with NVIDIA drivers put out in the last 4-6 months has SLI stoped crashing (used to crashed around the 3-4 hour mark)

[Oaktown]

In Crossfire the 2nd (3rd and 4th as well) card(s) are disabled.

[dirtyjohn_lv]

Even more reason to buy nvidia!

[Oaktown]

I don't understand your comment/reasoning so can you explain?

[Oaktown]

Display outputs are NOT disabled in SLI, not sure how it works in AMD Crossfire. I used 6 outputs regularly, the 7th (during summer only) and 8th when needed. The combined calculations are only used if the software supports it as far as I know.

SLI is a master/slave configuration which uses the 2nd (3rd and 4th) GPU(s) for calculations and sends the information to the master which is the 1st card just like AMD Crossfire so I'm not sure how you can drive 6 to 8 outputs when SLI is enabled on your NVIDIA cards! My understanding was that NVIDIA SLI was limited to 2 outputs for standard SLI configuration which is confirmed from the FAQ on their website:

http://www.geforce.com/hardware/technology/sli/faq#s1
MULTI-MONITOR
How many monitors are supported when running in SLI mode?
With GeForce R180 drivers (or later), standard SLI configurations for 2-way, 3-Way, and quad SLI support a maximum of two monitors. Additional monitors (up to 6 monitors total enabled) may be enabled by using either a motherboard GPU and/or a PhysX capable graphics card (GeForce 8 series or higher with at least 256MB of memory) that does not have the same GPU as those that are SLI enabled.

Is the SLI automatically turned off when you don't run a software that uses it?

[dirtyjohn_lv]

I don't know about turned "off". It's never used in the first place. I'll take a screenshot when I get back to the machine. Resolume has no SLI/crossfire settings so they don't utilize this part of the card, even though it's on. Same way stuff like OpenCL /Open AL are included in card. They've said before the only card used for processing is first GPU, so SLI would never come into play.

OR

Resolume outputs master texture/OpenGL context as 1 output and spans the monitors you need (much the same way you would a triple head or something similar)

[Oaktown]

With AMD, you need to turn it on for Crossfire to work so I always keep the bridge on and turn Crossfire on or off in Catalyst depending on my needs:

• If I turn it off, I have access to the two video cards and all outputs (12 total if I use MST hubs on my R9 270X)
  If I turn it on, it disables my lower card (the slave) which is used for rendering.

I dont' know if it makes a difference with Resolume but AMD Catalyst supports OpenGL.

[dirtyjohn_lv]

Here's a screenshot of my main system. SLI turned on with "Activate all displays". If I turn on Manage 3D, it behaves the way documented and you describe (only 1 output). Driver version 344.11

You can see Arena running ~60fps, with 1 video running (varies between 56 and 62)