I'm looking to make another PC sometime soon, getting my parts all ready in the checkout basket and saving it so i can see the prices drop and drop.
Im currently using 3x GTX 580s with 1.5GB of GDDR5 each, (I am skipping the 6 series as i don't think i warrant an upgrade just yet) they are powering 3 Acer GB245hq's. As everyone knows you want the best your pocket will feel it. Unfortunately 1.5GB at the extreme resolution of 5760 * 1080 while trying to max out games isnt really cutting it, and the 3 cards dont add each others rams to make a lovely 4.5GB. So...
Can i buy a 4GB GTX 685/780 GeForce card to occupy the 1st PCI-E slot and then buy cheaper 1.5/2GB cards to run in the 2nd and 3rd slots.
Money ATM isnt really an issue, but everyone wants the best bang for their buck
In a CrossFire or SLI setup both cards (of the same series like two GTX 685 or two GTX 780) should have the same amount of RAM because both cards will be load with identical textures. If you have a 4GB GTX 685 and a 2GB GTX 685, then only 2GB of textures will be loaded into both cards.
The card with the lowest amount of VRAM determines how much textures will be loaded on to the cards.