I am wondering if it is any ide too buy 2x GT690 or not?
Better is to buy for same mony 3x GTX 580 with give you somethink like 6x GTX 680
That´s absolutely not true. While the GTX680 is a bit slower than a GTX580 it is no way near half the speed. So yes very possible and the nice thing is that you only need two PCI-E slots. If you got PCI-E 3.0 and you have a board that can do 2x 8.0 that is very sweet as you will never be I/O-bound. Apart from that, it will probably not be worth the cash unless you are into hardcore gaming @ 5120x2880 / 5120x3200. Also 2GB per GPU will most likely be a heavy constraint at those speed levels ( 4x GTX680). If you contemplate on going GPGPU seriously wait for GK110 to reach consumer levels.
Moved from “General Forums > Blender and CG Discussions” to “Support > Technical Support”
Well, I have a GTX680 since launch that replaced my GTX580. But aparently you seem to agree that his statements where exaggerated ? And you can still change voltage and fan settings if you still feel the need for it via nibitor, it is just capped at 1.21V on reference cards. Anyway, wait for GK110 !
So yes very possible and the nice thing is that you only need two PCI-E slots.
-anaho
That depends on the size of the video card.
First check to see how big the card is compared to the PCI-E slots on your board…my Zotac GTX580 Amp!
only uses one slot, but it covers the 2nd slot completely…no way to put in 2, though other boards may have room.
Also they run hot and draw a lot of power…probably would need to increase cooling & power supply.
What I meant was that you only need two 8x Gen3 slots for the same bandwith as with two 16x Gen2. As far as I know two or even three 16x Gen2 are reserved to very pricey boards only. I dont know if PCI-E bandwith makes any difference for Blender though, probably not.
Good…didn’t know that. 
My point was that the newer cards take up a lot of room, and need to plan ahead when choosing a mainboard…I didn’t realize that when I put together my system last year.
But it runs great, and really don’t need 2 gpu’s for rendering.
I have 2 instances of Blender 2.64 going at the same time on 2 different animations (output to different folders) no problem. 