Or basically:
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Power = Current x Pressure
Watts = Amps x Volts
P = I x V
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P = I x V
I = P / V
V = P / I
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P = I² / R
Considering the results others found in the original post, this theory seems to hold true (calculated using the formulae above and with tests of my own), with the power drawn being higher as the voltage drops.
When working with wires as small and long as the traces on the Gamecube's PCB, the wire's resistance has to be taken into account. This is often a problem when trying to re-wire traces after trimming a board and finding the board has stopped functioning correctly, running the game/sound at the wrong speed or pitch, if at all.
Because of these small traces, portions of the motherboard will get hot, including but not limited to the IC's such as the central and graphics processors, and often the memory depending on the software you're running.
From all of these we can draw several advantages and disadvantages that arise when using a lower board voltage, and what this means for modders.
Advantages:
- The lower voltage limit allows us to use the same or very similar voltages across the board (requiring less power regulation)
- Builds can be cheaper because of the ability to omit expensive power regulation devices
- More space is available and/or saved because this
- Simple discrete devices will use slightly less current (LEDs will be more dim in some cases)
- The lower voltage causes higher current draw, which means more heat
- Heat in electronics is lost energy, which means that the more heat produced, the more power you lose
- Because heat is increased, better cooling (often fans which draw more power still) are required to keep the unit operating correctly
- CPUs and other such devices will still run on lower voltages, but without enough power their performance might wayne slightly
Because more cooling will be required, several sacrifices will have to be made that will negate most advantages. These include, among other things:
- Fan will be required, a fan is usually included in most portables regardless, however larger fans may be needed to allow the system to operate properly
- Larger fans mean more noise
- Increased current draw from fans and heat dissapation mean lower battery life
The voltage of the board's 12v rail isn't as sensitive as first thought. This means we can use cheaper regulators that don't get precisely what voltage we want (eg. 10.5v or 9.8v etc.) that will still work with the system, and it will run fine. By the same token, if your battery voltage total is between 9-12 volts, you won't need to regulate the voltage running to the system, and will only need a step-down DC-DC converter for the 3.3V (which you'll need no matter what.)
I wouldn't recommend using less than 9 volts, as the lower you go, the heat increase grows very quickly.