Some of the newer 1.8" SSDs use the 3.3 Volts, But to the best of my knowledge all 2 1/2 in SSDs and HDDs use the 5 Volts.
the Molex -> SATA adptors ONLY provide the +5 and +12V. and can NOT be used on the 1.8" 3.3 V SSDs.
enclosures for 2 1/2 in SSDs/HDDs use the +5 V (USB supplied power) which is applied directly to the SSD/HDD.
Internally the 2 1/2" SSD could be either +5V or +3.3 V. But if 3.3 V would reqire a converter circuit to step the +5 down to +3.3 V.
For the 3.3 V 1.8" SSDs a special encloser would be required to step 5V -> 3.3V
For direct connection to sata Power connector, this is not a problem as the correct pin suppling the voltage is mapped internally. Ie with a 5V SSD ONLY the +5 v and return are mapped, the 3.3 V and =12 V pins are simply "open circuited" at the connector input.
Quote: 3) Supply 3.3 volt output for your SSD – 2.5″ hard drive bays found on laptops supply 5 volts. 1.8″ SSD devices require 3.3 volts. In order for your 1.8″ SSD to function properply, you would need to use an adapter/converter that has 3.3 volt output