Could all new PC motherboards only require a primary 12V rail?

[japlytic]

This is a possibility, but future PC motherboards could only require a single 12V primary rail with +3.3V/+5V (-12V is only required for PCI slots (and certain cards thereof) but not PCI Express slots) switching regulator circuitry (which is now quite compact for their high output) on the motherboard with SATA power output connectors on the motherboard.
Most newer ATX (and related counterpart) power supplies over a certain wattage typically have a single primary rail of +12V which is then connected to independent +3.3V/+5V/-12V switching regulator modules; also, many hot swap server PSUs have a single primary rail of +12V.

[lti]

Re: Could all new PC motherboards only require a primary 12V rail?

Some computer manufacturers already do that. My parents have a goofy oddball Dell like that. That means that I need a SATA power cable for the 2.5" bays so I can install an SSD "properly" instead of throwing it in the 3.5" bay.

[dmill89]

Re: Could all new PC motherboards only require a primary 12V rail?

Some computer manufacturers already do that. My parents have a goofy oddball Dell like that.

Many OEMs are doing that now. Dell, HP, and Lenovo have all been doing it for several years now (and of course all with their own proprietary connectors that aren't compatible with each other).