Power supply connection to MSI 280x GAMING

[bvault]

So I have powered risers (2-pin Molex)
My PSU has dual 6-pin and 8-pin (6+2) cables
MSI 280x has a 6pin and 8-pin slot.
MSI 280x also comes with a 6-pin to two 3-pin molex-looking connectors AND an 8-pin to 6-pin connector

PLAN
Three 280x's and 1200W Silverstone PSU
I was just going to connect the PCIe power cables [each dual 6-pin and 8-pin (6+2) cables] to the respective 6-pin and 8-pin slots on the GPU.

QUESTIONS
Is the plan sufficient?
Do I need to connect the molex on the risers with this set up?

[bvault]

What about the extra cables that come with the GPU (as described above)? Do I need these?

[Starscream]

It's better if you do use the risers to ease on your mobo (less current goes though it = less chance of frying your mobo) , so yes, power the risers.

As for your second question... if your PSU doesn't have enough PCIe power connectors for all your GPUs, than yes, obviously use it.

[bvault]

It's better if you do use the risers to ease on your mobo (less current goes though it = less chance of frying your mobo) , so yes, power the risers.

I know this already. You probably did not get what I am asking. Yes I am using riser cables AND they have the molex connector. My question pertains connecting the molex vs. PCIe power connectors. Do I need to connect molex if I have connected all the GPUs to PCIe PSU coonectors?

As for your second question... if your PSU doesn't have enough PCIe power connectors for all your GPUs, than yes, obviously use it.

I have enough for each gpu. See my question above