to the left of the cpu, there is pairs of mosfets, sometimes cooled together. I recently had to study this stuff, my motherboard melted a mosfet and even had a small fire with a 103w presoctt on a ms6728...the ms6728 cheaped themselves to 3 pairs instead of four (fu**** as****!)
I learned a phase is simply the same volts and amps, simultaneous, it makes things clean. on a mtotherbaird, there is many places to spread it out...hence needing a "four". (aircraft have had 3 phase in lower volts for a half a century- but hard wired, not spread across a mobo with 6 layers)
I look for four phase..no less, and solid caps seem to be proving themselves as well, (they are right near the pairs).. and if it is four phase, alot of times coolers are not needed, even for hefty cpu wattage. Excellent on workstation integrity, ecc ram seems to find nothing, even in storms of all electron kinds..
nothing special, it is a standard in other words. A psu and whatever decent mobo combo, can change this four phase hype