Jimbo832 :
The Corsair CX comes under tier 3 which says "These are still solid units, which still supply stable power to your system"
They're OK, not great. In other words, they will probably be fine for a budget general-use machine that does not push the PSU much. For a high-performance system, which includes anything with multiple GPUs, you will want something in Tier 1 or 2. CX series also has a reputation for cheap components that are prone to dying after a few years, which you do not want.
In any case, that Capstone unit is better quality than the CX750 and also cheaper right now.
GRUxTSAR :
You cannot do it on 650w. 562 for the GPUs alone plus another 100+ for the CPU and another little bit for the other components. Even 750w is cutting pretty close
That was full system power consumption, not just the GPUs.