Just a suggestion. I'd get a X4 955BE (on sale $115), it'll be just as fast as that X6 in gaming and overclock better, and you can keep the money you save for a bulldozer upgrade down the road or better yet, a better graphics card than a 550ti. Change it to 560ti. You'll be happier with your machine.
Also you don't want 3 sticks of memory. You need memory in pairs, such as 2 sticks or 4 sticks, not 1 or 3. I'd get ddr3-1600 cuz bulldozer will take advantage of the extra speed. You don't need 12GB, 8GB is more than enough. These Gskills are perfect.
That's a very expensive motherboard designed for 3 graphics cards . You are installing one relatively weak graphics card so its a complete waste of money .
You can have the exact same performance from your motherboard for over a $100 less
You also seem to be saying that you are going to install 3 x 4 gig of RAM , or 3 x 4 kits of 2 x2 gig?
The first option will run in single channel because you have the three sticks pspread unevenly across two channels . The second option is 6 RAM sticks which cant possibly fit in 4 slots
As far as PSUs are concerned, be informed. Before you buy any PSU read accurate, objective PSU reviews at reputable sites such as www.jonnyguru.com or www.hardwaresecrets.com on the EXACT model PSU that you are interested in as some brands have good and poor quality PSUs.
You can also get an accurate rating of how much PSU power is required for your current or future system at the PSU calculator link below. Once you know the total PSU watts required then you need to confirm that the 12v rail has enough amps. to support your Vid card(s) and the rest of the PC system.
There are several websites that show the Vid card power consumption in watts. Divide the watts by 12 to determine the amps. required on the 12v rail(s). Add 15 amps for the rest of the PC on the 12v rail and you now know the Minimum total 12v rail amps required under full load. It's best to have at least 5-10 amps. reserve on the 12v rail available under full load so the PSU is not loaded to 100%.
It's also worth noting that people often misunderstand the 80% power rating. This is a rating of the PSU's energy efficiency not it's output. 80% plus PSUs use less grid power to produce the same PC power. If it's 80% Bronze, Silver or Gold the cost savings on electricity is pretty small between Bronze, Silver and Gold unless you are paying very high rates for electricity so any 80% rated quality PSU is fine even if not Gold. For those who leave their PC on 24/7 a quality 80% PSU is a good investment.