i am going to have enough 8 pins for the gpu's, i will be using 1200w for 3 gpus plus risers and the motherboard and one 1000w for the rest 3 gpus. im just going to used the satas that came with the riser to power them up
Some people recommend to not use the Satas.
I’ve been using them though without any issues.
You have been lucky - the SATA power connector ITSELF is only rated for 54 watts max draw on the 12VDC pins - the PCI-E BUS is specified to have up to 75 watts drawn from it (and some cards in review testing have been shown to pull more than THAT at least some of the time on peaks).
If you are running the card in a "low power draw high efficient" setting, it might work OK for a long time - but why take the risk when MOLEX powered risers are no more expensive and DO power the riser safely (156 watt power rating on a MOLEX connector, just watch the WIRING for those).