Turbo boost isn't overclocking, it's a built-in method of increasing the speed of the processor.
http://www.intel.com/support/processors/sb/cs-029908.htm
"Intel® Turbo Boost Technology is a way to automatically run the processor core faster than the marked frequency if the part is operating under power, temperature, and current specifications limits of the Thermal Design Power (TDP). This results in increased performance of both single and multi-threaded applications."
Overclocking is manually (or via software) changing the settings of the processor to make it run faster.
For the Sandy Bridge processors, you should buy RAM that is 1333 speed. (PC3-10666)
You should always buy RAM in a kit of matched DIMMS, and buy as much as you think you'll need. If you want 4 Gb, (plenty for most games and applications, but either one 4 Gb DIMM, or buy two 2 Gb DIMMS like this:
http://www.newegg.com/Product/Produc...82E16820226092
(several manufacturers, that's just an example)
Avoid the RAM that's 1.65 v. The Sandy Bridge processor is designed for 1.5v. (even though 1.65
should work.)
Most motherboards documentation specifies what slots memory should be in. Usually something like "A1 and B1" for dual channel capabilities with 2 sticks of RAM. You need to pay attention to what sockets you install the memory into...if you choose wrong...your computer may not run.
Dual graphics cards, (SLI or Crossfire) is a way to nearly double your computer's graphic speed. (You don't actually get twice the speed of one card, but you SHOULD get ~25% more speed with two)
Depending on what games you play, a single card is USUALLY plenty...if you buy a quality current generation card.
(of course, hard-core gamers swear by dual cards...but I could never justify the extra cost or power draw)
Will you have the need for 2 video cards? That's up to you and what games you want to play at highest settings.
