Maybe not a case since most cases are longer now.
Also there are P55 motherboards that have 1 PCI-E x16 and 1 PCI-E x8/ slots (the x16 slot gets "downgraded" to x8 if you are running 2 GPUs) for Crossfire/SLI. X58 motherboards have 2 or more PCI-E X16 slots. Recent benchmarks show no real performance gain in games when you have 2 gpus running on x16 slots over 2 gpus running over x8 slots.
Personally I think X58 motherboards are a waste of money. I don't run more than one GPU nor do I overclock anything. But if you want this to be a beast for the next 3 years, then an i7 system may be what you need. You never know what type of games will come out in the next 3 years.
I have a P45 motherboard, E8400 C2D processor, 4GB RAM, Radeon 4870 and I haven't played a game that I didn't have enough horsepower to enjoy the game. I built it 2 years ago.
So you suggest the "Gigabyte GA-P55A-UD3". I see there is a variety of them (UD2, UD4, UD6), is there any point to go for a higher UD-number?
You said "i5 760 or better", what is better than the i5 760? Or did you mean i7 by that?
Let's say I decide to go for what you suggested, are 4GB ram enough or would it still be a good idea to go for 6GB? Just to have a bit more performance and juice? Or must it be 8GB then, because i5's are dual channel memory?
To you and the other guys a thank you, helps me to get a clue.