I'm quite new to PC gaming and I know nothing about it. I decided to invest some money on building one. This probably gets asked a lot but I'm looking to build one in the $$600-$800 range. I want to be able to run current games (if possible) such as BF3, Crysis 2 in Ultra/High settings. I'm also a cinematographer and would love to edit videos with it. Your recommendations are appreciated!
$800 it may be difficult to get you a better video card. Depending on how heavy into video editing you're into would change my mind on which direction to go with the build. If its light video editing and more emphasis on gaming, I would use a Phenom II CPU which will allow you go to heavier on the video card. A Phenom II will "get the job done", but for heavy video editing, I would go with the Intel. (Video editing ironically doesn't require a particularly powerful graphics card)
Or alternatively, you could increase your budget slightly and use the 7850 in the i5-2400 build.
In answer to a couple questions you raised when you filled out the form:
Overclocking: This is when you manually adjust the parts in the computer to run faster than they normally. Now, both of these CPUs I recommended have the capability (not all do). The Phenom II can be manually overclocked from its stock setting typically they're good for about 4.0-4.2GHZ (which by default the 965 model is 3.4GHZ). The intel i5-2400 is a locked CPU, meaning it cannot be overclocked manually, however it does overclock itself the CPU will "detect" when the higher speed is needed to handle the workload and will adapt itself accordingly.
Now you can get an Intel i5 that can be overclocked manually, but they cost a bit more, particularly the i5-2500K, or 3570K (The K denotes the CPU is unlocked in the model numbers)
Keep in mind that when overclocking the CPU, a more efficient CPU cooler is usually needed. Decent ones run about 30-50 dollars. A Phenom II on the stock heatsink cooler is good for about 3.7GHZ give or take since every CPU is different in terms of its tolerances.
What is Sli/Crossfire? This is when 2 video cards of the same kind can be run together in tandem to increase performance. For example, if today you bought a 6870 and 2 years from now you needed a little performance bump, you could add a 2nd 6870 card into the computer. Although typically 2 cheaper video cards in crossfire/Sli will not outperform a single better video card. (Example: 2 Sli Nvida GTX 550 TIs will not out perform a single GTX 580)
There are 2 manufacturers of Video cards, AMD and Nvidia. Crossfire and Sli are the exact same thing, the difference is Crossfire is referred to for AMD cards, and Sli is for Nvidia cards.
Another thought on your system, since you're relatively new to this whole thing, I withheld my recommendation of an AMD Bulldozer FX-8120 model in lieu of the Phenom II 965. The problem with this CPU is at stock speeds, they tend to suck, however under heavy overclocking conditions, they can easily perform up to the standards of a more expensive Intel i5-2500K when overclocked. (Which means if you wanted to go this route, you would want to overclock it fairly substantially), although the 8120s can get quite power hungry when overclocked, so it would be ideal to go with more than a 500 watt PSU such as I recommended, I would also say this is true if you were to purchase a 2500K and overclock it.
The reason I link to this benchmark is merely because there is currently quite a bit of "flamewarring" going on regarding the Bulldozer series CPUs. You know how it is when you get a Honda owner and a Volkswagen owner in the same room?
I really appreciated all the explanation you did nekulturny . The PC i'm trying to build is mostly for gaming. I'm currently using a Mac for editing. And like I said, I want to be able to play graphical intense games on high (if possible) settings without exceeding my budge ($800). Which build would you recommend for me (Like I said, I'll be using it for gaming)Thank you so much for the time and effort to reply to my thread, I really appreciate it!
EDIT: I can probably scoot my budget to $1000 max, and also is i5-2500K a better choice?
The 2500K would be the better choice when neither of them are overclocked, although the FX-8120 would be equally good provided it were overclocked heavily. The 2500K is good enough at stock speeds. The Phenom II is a decent CPU, but it is beginning to show its age (its an older generation CPU, but still very competent in 2012)
If you wanted to get into serious overclocking and have your good game settings I would run with the 7850 video card and go with a stronger power supply. I've included a decent aftermarket cooler:
In games the video card matters the most more often than not for single player games, online multiplayer, tends to rely on the CPU a little more and the 7850 is about the best you can do without spending >$300 on the video card. The GTX 570 isn't any better in most cases, the 580 is $400, 7870 is $360, etc) Keep in mind, the 7850 I linked to is factory overclocked, so it will perform a little better than these benches.
Edit: I went back and changed a couple links in my builds, I mixed a couple of them up, (since I copied and pasted a notepad file of recommendations I have saved so I can modify them). The links all match the parts now. BTW, its my birthday, so I'll be heading out for a bit, and most likely will be returning home later tonite drunk, so best to make sure I have the links fixed right away