The board you posted originally was great. I would only listen to these threads for awhile, because everyone in the world has their opinion, and if you listen to everyone, you'll change your mind 100 times and never get to start
What he meant by not supporting "full SLI" is that it doesnt do 16x on both PCIe slots. If you have 1 GPU, the PCIe slot you are using does 16x, but if you have 2, they both do 8. This is perfectly fine. There are studies that show 8x only loses a few FPS over 16, so don't waste money to get a dual 16x board. I would also look into raid black drives before you do it. I think you have to get the raid version of them, and be sure to understand it before you invest in it. If you have 2 drives in raid 0, they get twice the performance as 1, but also act as one hard drive. If one dies, you lose everything on both. I think if you are a new builder, you should really start out basic and go from there. Get 1 WD Black drive, 1TB is probably a good start, and use it for awhile. Study SSDs to make an educated choice, and when you are ready, purchase an SSD as a boot drive, and use your TB Black drive as storage/app installs. I dont know about every board, but the Asus boards should easily overclock the CPU GPU and memory. Just be sure to do a lot of research on overclocking before you dive in. Its easier with sandy bridge than previous CPUs, but don't change things that you don't know what they do. And as for level of overclocking, you should be able to get 4.5-4.6 easily with that board and CPU cooler under safe voltages and temps.