Lets start with the 600 Series Video Cards
650 - $110
660 - $220
670 - $399
680 - $470
The difference in the price reflects the difference in CUDA cores and memory on the card. The more cores and memory, the more expensive. But lets talk reality... If you are running a 24 inch or smaller, you really dont need the 670 or 680. The 670 and 680 will allow you to run max settings on higher resolution monitors that are bigger than 24 inches. For the majority of gamers, the 660 will run max settings at 1600x1200.
You can spend more money and your benchmarks will show better numbers but I honestly doubt YOU could tell the difference between running a game on a 24 inch monitor between the 660 and the 670. Honestly, can the human eye tell the difference between 60 fps and 79fps?
I'll leave the i7 question to someone else but as far as memory goes, you might as well go with 12gigs at least since memory is so cheap. Memory is always used and 12 gigs seems to be the sweet spot on todays gaming rigs. If you have the cash, you might as well get the whole 24 gigs. but if you are trying to get the most bang for your buck, 12 gigs will serve you well.
Hope this helps
Can anyone please help me with the specs and such?
which one of the 600-series GeForce GTX GPUs are needed for which kind of needs?
What's the difference between each of the intel core i7 processors?
and how much RAM do I need for a killer Gaming experience?
and is there something I seem to be missing?
If you guys can answer these questions and help me with this I will be so grateful that I will need a poem to express it!