Maximus III gene

[edy77]

Thinking about buying this board. Can anyone answer my questions:

I have 6gb DDR3 (3x2). There are 4 DIMM slots. Will this config limit performance. Should I get another 2GB to populate all 4 slots?
If I choose to run 2 GPUs in SLI, will the x8, x8 limit performance or will I not notice?

Thanks,
Si.