Well it has been only four days, subsim members are prone for staying submerged as long as possible
And i am not a specialist, i am struggling myself every 4 years, when a new PC is 'needed' (for whatever reason), to find out the latest news and improvements.. i think the one-generation-backwards cpu to be the better choice (financially, and from the bug-free pov), but then get the fastest one, with the most 2nd level cache. Also, four cores should be present. The machine feels much more relaxed, while running Adobe InDesign and Silent Hunter, at the same time
650 watts PSU sound reasonable, though i do not know about the needs of a SLI configuration running two vid cards.
Regarding mainboards
http://www.tomshardware.com/t/motherboards/ is always a good address. Personally, i prefer Asus or Gigabyte mainboards, had some good experience with those. Asrock, not so much..
Everything else, i'd say with a 64bit operating system i would straight go for 16 Gb of Ram, and the mainboard should be able to maybe expand to more later, via free slots (e.g. four slots, insert two 8Gb ram chips, so you have space to expand).
Also dual channel configuration (pairing identical ram chips) is usually a good idea, for further boosting the fsb (front side bus) internal data exchange speed.
No more ideas, especially when it comes to mainboard internal techniques
