Seasonic G vs Corsair HX

Solution
The hardwired cables are:

Seasonic SSR-650RM
20+4 pin ATX connector: 550mm
4+4 pin EPS/ATX12V: 550mm
6+2 pin PCI-E+6+2 pin PCI-E: 550mm+100mm <--- This is what the Corsair HX650 has left off

Corsair HX650
ATX Cable (24-PIN): 610mm ± 25mm
EPS12V CPU Cable (4+4-PIN): 650mm ± 25mm


Modular Cables:

Seasonic SSR-650RM
5.25"+5.25": 300+125mm
5.25"+5.25"+5.25": 400+125+125mm
SATA+SATA: 305+120mm
SATA+SATA+SATA+SATA: 400+120+120+120mm
5.25" to 3.5" adapter: 105mm
6+2 pin PCI-E+6+2 pin PCI-E: 600mm
6+2 pin PCI-E+6+2 pin PCI-E: 600mm
CPU 8Pin: 650mm <--- Corsair HX650 doesn't have this cable

Corsair HX650
2x 600mm ± 25mm 1 connector PCI-E Cable
1x 700mm ± 25mm 4 connectors SATA Cable
1x 850mm ± 25mm 4...
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.

The Seasonic G-650 (SSR-650RM) has:
20+4pin 55cm, 2x ATX12V 55cm, 4x 6+2pin PCIe, 8x SATA, 5x 4pin peripheral
 
The hardwired cables are:

Seasonic SSR-650RM
20+4 pin ATX connector: 550mm
4+4 pin EPS/ATX12V: 550mm
6+2 pin PCI-E+6+2 pin PCI-E: 550mm+100mm <--- This is what the Corsair HX650 has left off

Corsair HX650
ATX Cable (24-PIN): 610mm ± 25mm
EPS12V CPU Cable (4+4-PIN): 650mm ± 25mm


Modular Cables:

Seasonic SSR-650RM
5.25"+5.25": 300+125mm
5.25"+5.25"+5.25": 400+125+125mm
SATA+SATA: 305+120mm
SATA+SATA+SATA+SATA: 400+120+120+120mm
5.25" to 3.5" adapter: 105mm
6+2 pin PCI-E+6+2 pin PCI-E: 600mm
6+2 pin PCI-E+6+2 pin PCI-E: 600mm
CPU 8Pin: 650mm <--- Corsair HX650 doesn't have this cable

Corsair HX650
2x 600mm ± 25mm 1 connector PCI-E Cable
1x 700mm ± 25mm 4 connectors SATA Cable
1x 850mm ± 25mm 4 connectors SATA Cable
2x 750mm ± 25mm 4 connectors Peripheral Cable
2x 101mm ± 25mm 1 connector Floppy Adapter
 
Solution
They both use a temperature controlled fan.

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.