You guys might be out of luck here.

 

According to nVidia in a Surround SLI setup one monitor must be connected to the second video card.

 

http://www.geforce.com/whats-new/guides/how-to-correctly-configure-geforce-gtx-680-surround#3

 

Ok this is for the 6oo series but I assume it to be the same for all cards.

 

gb.

 

 

This is correct. Basically, if you want to run in a non-surround mode using max 3d performance, but still have all of the monitors running, connect all three to one display. If you plan on running surround mode, you MUST have at least one display connected to your second card. If you run max 3d performance in this mode, it will power off two out of three monitors when in that mode. 

Surround mode doesn't matter for P3D2.2.  In fact in my experience with my system with 3 monitors here I think it hurts the frame-rate.

I'm not sure VRAM is going to matter yet, not until the 64bit hurdle has been crossed.  For most people who are not pushing past 3 fullHD monitors or a 4k monitor it won't matter.  I've been monitoring 3 fullHD screens in many games now and memory has not been an issue.  3GB is just enough.  There may be some limitations, there are some reports of extreme cases going to 3.5GB usage on Titans, but again, very large viewing demands.  And that was a year ago when I researched the issue, before some of the driver updates.  There is no need to go to 6 at this time.  

I'd consider a 4GB VRAM card to be a high VRAM card, though I know 6GB 780's are on the way.  Has anybody tested what the impact of high cloud shadows settings on the GPU are?  Do they require more VRAM?  More core speed?  More everything?

Memory isn't the problem with clouds.  I believe that clouds shadows in bad weather will benefit to be functional with SLI.

Could someone please explain to me how expanding Vram beyond a 4Gb card can be beneficial, as I understood both FSX and P3D is bound to a max of 4Gb due to it's 32Gb architecture, thanks.

VRAM is not VAS.

VRAM is still limited to 32bit addressing.  Period.

VRAM is still limited to 32bit addressing.  Period.

 

That's what I thought.

VRAM is still limited to 32bit addressing.  Period.

 

This is true, but really only applies to anything mapped by the os/app/dx itself. The GPU can use whatever amount of the remaining VRAM for on-GPU processing,  things like anti-aliasing, etc, and that isn't impacted in any way by the 32 bit addressing limits of the app. If I force something like 8xSSAA in the driver, P3D is completely unaware that I have done so, and the GPU will use as much VRAM as is required to apply that processing.

 

As an example, Battlefield 3 (as with most games) was not 64-bit, and that would chew up VRAM like nobody's business.

 

You'd still likely end up being ROP limited before it became much of a concern, assuming a single GPU config.

 

EDIT: Just to add that on the other end, hitting VRAM limits is very painful. Single digit FPS/severe stuttering painful. That doesn't mean everyone needs 6GB cards, but is just something that can really ruin your day.