Posted 29 December 2010 - 10:39 PM
RAM: AMD's standard is DDR3-1333, anything above that is overclocked and may require a setting in the BIOS be changed for use at faster speeds. The number following the DDR3 moniker, such as 1066, 1333, etc., are speed ratings. Not all motherboards take all speeds and will downclock the faster RAM if necessary. You can use any number of RAM slots, however, AMD's motherboards allow for dual channel so you get a little better performance if you use two or four slots. The performance difference is minor and largely not noticed in day to day activities, just like overclocking RAM.
CPU: Keep in mind that only programs that are designed to utilize all six cores will take advantage of them, otherwise they will be limited. Otherwise, they are limited to four, two, or one core. The program Handbrake loves six cores. This is true for all multi-core CPU's.
Motherboard: The reason the 870 is cheaper than the 790FX you originally chose is the chipset. AMD chipsets have a number, such as 870, 790GX, 890FX, etc., which denotes certain features. The FX at the end of the number indicates that it is a premium flagship model that has high PCI-Express X16 speeds when using more than one GPU. The 770 or 870 are standard motherboards, nothing at all special about them. Think of those as basic models. Then there are the G and GX models. The G model is usually designed for HTPC's and are of no use for your purpose, the GX is essentially an 870 or 770 motherboard with a low-end on-board graphics card built-in. MSI makes good motherboards, so you should be good to go.
PSU: Newegg reviews should be taken with a grain of salt as people will complain about everything, even problems they created. The Sparkle unit is higher quality, judging from the specs, and is also modular so you use only the cables you need.
Case: Again, be careful with the Newegg reviews. I still stand by the Cosmos. Looking at those two units, they are very similar, one is made of steel, the other steel and plastic, one has fewer fans, but they are larger fans. I would go for whichever one appealed to you the most.
Graphics Card: With AMD/ATI, graphics card numbering tells you how they are positioned on the market. With the new Radeon 6 series, AMD has shifted the number around a bit. Before, the x8xx series of GPU's were high-end, now, the x9xx series is high-end. Also, AMD has retired the ATI name, finally. The card you should get depends on what is defined as light gaming. My current graphics card is a Radeon 5850 and I get excellent framerates in Mass Effect 2 (Even with super sampling anti aliasing), Final Fantasy XIV, and just about any game I have playing at 1920 x 1200 resolution. But, I don't play games requiring fast reflexes so I can get away with a lower-end model. I would go for something in the Radeon 6800 series, preferably the 6870 as it has the power to at least allow for good frame rates over the next several years.
OS: That Windows 7 version is an OEM/System Builder copy. The software is exactly the same, only the license is different which basically says you provide computer support (Who calls Microsoft for support, anyway?) and you are forbidden from transferring the license to another computer. Microsoft defines a computer based on the motherboard, so, new motherboard, new PC. This is only a legal limitation, not at technical one, you can still very easily get around this.