Power phase question.

[Sleeper]

I've had this question for a while. I'm fairly sure I am correct but wanted to ask anyway.

Most homes run on single phase power, and many industrial applications are three phase. I know what those are.

On motherboards, GPUs and the like we have power phases. My question is. Do these power phases behave in the same way as 120/240 and 208 volt single and three phases respectively or is it different?

[buran]

it's not the same. Your computer runs on DC, not AC. The power supply has AC Adapter to transform AC to DC.
As to motherboard phases:
https://www.hardwaresecrets.com/everythi...circuit/4/

[Larz60+]

I think it's a misnomer, my understanding of what is called a power phase is really a transformer, possibly with regulation, that converts from one voltage to another, or regulates a source with same voltage. The reason it's called a 'phase', i believe, is that a motherboard (or even a CPU, like Haswell), may use distributed 'phases' to spread the job over more 'phases' in order to reduce load on each, and thus less heat.

[Sleeper]

Thanks. I was thinking that the phases were somehow linked the frequency of the item they powered. Which didn't make much sense to me as I could have several cores all running at different speeds.

So my motherboard is an 8+3 so power going to my cpu is sent from just one of the 8 at a time.
The phase settings for my motherboard are starting to make sense now.

It was so confusing how you could (applying what I know of multi-phase power outside of computers) have a cpu/gpu/ram run on different motherboards each having a different phase configuration.

Thanks so much to both of you guys for clearing up my question.

[DeaD_EyE]

Our 3~ AC Powersupply looks like this:

def plot_sine(Ueff):
    max_voltage = Ueff * math.sqrt(2)
    x = np.linspace(0, np.pi * 2, 3600)
    x_time = np.linspace(0, 1/50, 3600)
    plt.xlabel('Time in ms')
    plt.ylabel('Voltage in V')
    plt.title('Time vs Voltage at 50Hz 3~AC')
    for n in range(3):
        roll = -(3600 // 3)
        y = np.sin(np.roll(x, -n*roll))
        y *= max_voltage
        plt.plot(x_time, y)
    plt.legend([f'Phase {p+1}' for p in range(3)])
    plt.show()

Result:    


The DC (direct current) Power supply don't have a phase.
If you draw them in a plot, you'll have straight lines.

If you measure the power against +12V and +5V, you've a difference of 7V.
Usually the devices are connected to one power lane and ground.
Each lane has the reference potential to 0V (ground).

If you compare this to our 400V 3~ net, the earth and neutral conductor is the reference ground.
The difference is, that it's alternate current and the 3 phases are shifted by 120°.

400V is Ueff, the effective voltage. The maximum peak is Ueff * math.sqrt(2).
To calculate Ueff to neutral conductor: Ueff / math.sqrt(3)

If you go further and add capacitive/inductive load, voltage and current have also a difference in phase.
At the end you'll see in a plot negative and positive power. It's used for example to feed power back to the net.
In industry you don't want to have blind power. They compensate the inductive part with big capacitors.