GTX 660 ti questions - upgrading my Octane rig

[pixelrush]

Hi all,
Recently I embarked on building a new CAD workstation also with the intention of enabling better Octane rendering performance via a more useful mobo and power supply for multiple graphics cards.
Its all but finished now except for the final choice of rendering graphics cards to go with a Quadro 2000.
I am thinking of 3xGTX660ti/3gb or perhaps waiting until the Kepler refresh is out for the equivalent in the 760ti/3gb.
To me this card seems like a reasonable compromise between vram space, performance, and cost, for moderate use.
3x GTX760 ought to be about 5x faster than my existing single GTX460/2gb so I could be quite happy with that.
My questions for other users who have 660ti/3gb are:
Are you generally happy with the performance of this card?
Is 3gb enough for your purposes? or is 2gb actually enough in practical terms? I'm not doing arch viz presently but I might pick up some work along those lines occasionally. My usual scenes aren't very big but I would like to increase my texture use. The extra number of textures for Kepler cards is attractive for this purpose. An alternative to the 660ti/3gb for much the same money would be GTX670/2gb....more performance but less work space....
If you have more than one 660ti do they 'breathe' well next to one another?
I am looking at the two variations of cooling available; large multiple fans which blow onto the heat sink fins but don't vent outside the case, and the single fan style that blows out the end slot and wondering which is best.
Various reviews tell me the first type are quieter and cooler however I am not sure how well they work in a close stack of three. I can't find a decent sli review that talks about this aspect. The actual air flow in the case could be hard to anticipate and might be quite variable with the topmost card suffering from the rising and turbulent heat of the others. My own thought is that the blowing out the end slot type might be better for Octane.
I have a Silverstone Air Penetrator fan aimed at the front of where the cards will be.
Any advice or experiences welcome.
Thanks
BTW I have 16 gb sys ram which should work well with up to 3gb vram and the PSU is 1250W/8 pcie connectors so it can run almost anything I can stick in the 3 spare pcie double wide slots even a fourth 660 in place of the Quadro.

[newske]

Can't help you too much directly but my experience, ArchVis related:

There is a huge amount of optimization you can do to your scenes to make the smaller. For me, I get by with 1GB Vram. This includes scenes with dense foliage etc. Making proper use of scattering and only using high poly meshes when required and it's no real trouble.

Of course, optimizing takes a little extra time. If it were one card, I would say the 670 would seem optimal to me if they are at the same price. Honestly though, it seems like you'll have 'enough' performance from the 3x660Ti that the extra 1GB Vram will be worth it. It would be really tedious to have all that power and not be able to load the scene you want.

Also, random note since I saw you use Rhino. If you're trying to get your obj's smaller (and load WAY faster) try exporting with a write precision of about 5-6. The file size is reduce by 1/3-1/2 and you won't notice the difference . Also working on animation Rhino > Octane...

[fovito]

[...]
If you have more than one 660ti do they 'breathe' well next to one another?

I have two 660ti OC and there is almost no space between them, the case and the cpu cooler. But even if I run Octance for more than 12h, they remain "cool" at 74°C (next to cpu) and 64°C (next to bottom of case). Best of all: you can barely hear them even under full load.

I am looking at the two variations of cooling available; large multiple fans which blow onto the heat sink fins but don't vent outside the case, and the single fan style that blows out the end slot and wondering which is best.

My 660ti have a mixture of both. There are two small fans on each card, which blow directly onto the heatsinks. The air flow of the card then leads the warm air to the end slots.

[pixelrush]

Thanks for the replies. I was hoping to keep the temp of all gpu less than 65degrees but that might not be possible.
I've decided I am going to wait a few months longer to see what the Kepler refresh brings.
I see in some early information that there might be a 35% or more speed up in the 770 due to some more cores and architecture changes but the 760 may only get a clock improvement and amount to 15% or so.
There might be more bang for buck elsewhere then than the 660ti. Maybe I can live with 2gb too.