I just recently upgraded my MoBo and Processor from a AMD Phenom II quad and a cheap 80$ budget motherboard to an i5-3570k with a $230~ z77 MoBo a month ago, and already I wanted to upgrade the GPU to a PCI-E 3 graphics card. I know where the prices are for the cards, but I currently have a 560 GTX (not TI) installed and I wanted to make myself a little future proof. Depending on the circumstances, I could get two cards and SLI, but currently I am only looking at one.
My question is, which of the current PCI-E x3 cards are the best on the market currently?
Pretty much for nVidia, the 670 would be your best bet. The 680 and 690 are great, but expensive, and also expensive to upgrade later.
It's easier to spend $350 every two years, than $600 every three years. Costs less, and you have less technology gaps. And the 670 is a beast of a card, unless you're doing something silly like triple monitors at max resolution playing crysis 15.
EDIT: Keep in mind that PCI-E 3.0 has no relevance in the market, as far as I'm aware, as there aren't any cards that as of yet that saturate the PCI-E 2.0 bandwidth line. A "PCIE2" 670 would be no different than a "PCIE3" 670. The technology is simply there, when its ready.
GTX 690 is the top card on the market right now, but unless you are willing to drop some serious cash for one like $1,200+ USD for one they are not worth it. A lot of people have been going with the GTX 670 they can easily be OC'd to GTX 680 with little to no stress at all and they are about $150 cheaper than a GTX 680. I currently just bought a GTX 670 for my new build, only thing left is to decide on a case. Haha I am indecisive. Below is a link for benchmarks for high end gpus. http://www.videocardbenchmark.net/high_end_gpus.html
As far as I've read, PCIE 3 cards are backwards compatible with PCI 2 boards... They're simply putting out PCIE 3 boards NOW, so when we get actual, real PCI E 3 cards that NEED it, you already have the board, instead of having to upgrade. It's actually a good idea, for once.