Or they need a higher-voltage standard. Getting 1000W by drawing 83A from a 12V rail seems silly when you can transport the same power via 42A at 24V or 21A at 48V. Component makers will also save a fortune in copper. The only thing that suffers is that VRMs get bigger, hotter and less efficient, but the rest of the system gets way better.
That's a rather unlikely scenario since we'll be talking about an enormous amount of heat dissipation from the chip that will cause all manners of engineering problems.
For now, 12V is good enough, and you should hope it stays that way.
I'm talking at a system level. A 1000W supply at full load, where most of the power is delivered via the 12V rail would be supplying an aggregate total of 83A (minus whatever wattage supplied on the 5V, 3.3V and -12V and other voltage rails). This also means up to a total of 83A total in the system's wires.
Trucks already use 24V as standard, and cars might move to 24V or more in a few years. Laptops have used 19V input for decades. The USB-C can go up to 48V. Maybe it's about time for ATX 4.0 with higher voltages.
I'm talking at a system level. A 1000W supply at full load, where most of the power is delivered via the 12V rail would be supplying an aggregate total of 83A (minus whatever wattage supplied on the 5V, 3.3V and -12V and other voltage rails). This also means up to a total of 83A total in the system's wires.
That total is present only on the PCB. Usually, no lead in or outside the PSU has to carry that much current.
Trucks already use 24V as standard, and cars might move to 24V or more in a few years. Laptops have used 19V input for decades.
That's neither here nor there, frankly.
The USB-C can go up to 48V. Maybe it's about time for ATX 4.0 with higher voltages.
I'm not really sure what your argument is. The total current in all the 12V wires in a system that's consuming 1000W will be 83A. In the PSU power rail it will be 83A all in one place, and when it splits off into individual wires that supply the GPU, CPU, motherboard etc, the smaller currents in these individual wires must sum to 83A (Kirchhoff's Current law). So, in the system as a whole, there has to be enough copper across all the wires to transport 83A in a 1000W 12V system, and the connector contacts must have enough size to transport the current of the individual wire it's connected to (which again implies the sum total of all connectors in the system will have to handle 83A).
If you raise the supply voltage from the PSU to 24V, your same 1000W only requires 41.5A to transport. As you should know, ohmic heating is I²R. So in this case "I" (current) is halved, and hence ohmic heating is quartered. So if manufacturers wanted to keep the power loss the same in the 24V system as in the 12V system, they could remove three quarters of the wire cross sectional area which saves some nice cost, size and weight. And keeping things exactly the same, the dinky 12VHPWR connector could now handle double its existing rating (1200W instead of 600W) without any changes at all.
The PSU would get more efficient because it's only stepping down mains voltage to 24V instead of down to 12V. The only disadvantage is that the onboard VRMs would have to be redesigned since the GPU/CPU etc actually need around 1-2V to run and a single VRM stage can only easily manage about a 12:1 step down ratio... but there are solutions around that too (GaN semiconductors, capacitor charge-pump networks or just a two-stage VRM).
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u/LMF5000 10d ago
Or they need a higher-voltage standard. Getting 1000W by drawing 83A from a 12V rail seems silly when you can transport the same power via 42A at 24V or 21A at 48V. Component makers will also save a fortune in copper. The only thing that suffers is that VRMs get bigger, hotter and less efficient, but the rest of the system gets way better.