Corsair HX650 (CP-9020030 / 75-001217) has the following cables (according to Corsair's website):
20+4pin, 1x EPS12V, 2x PCIe, 8x SATA, 8x 4pin peripheral
Corsair might have a pdf which states what the cable lengths are on this unit, but I personally don't trust that pdf because in the past I have found that their numbers do not agree with multiple reviews.
I don't think there is a fanless mode. I haven't been able to find any published info, from either Seasonic or Corsair, on the cooling fan profile for either model.
What info I was able to gather, based on reviews of the 550 Watt model, the fan starts off in low speed mode until the power draw reaches 50% when it is suppose to increase linearly to maximum fan speed when 100% power draw is reached.