[citation][nom]InvalidError[/nom]Using the heatsink to provide DC ground makes perfect sense since the heatsink has a whole lot more metal and hence lower electrical resistivity and I2R losses than fine traces on the CPU die, solder balls, substrate, socket pins and PCB traces which could significantly reduce DC power losses there. This would make it possible to eliminate ground pins used mainly to provide DC ground but some ground pins would still be required for AC components that still require a low-impedance path with minimal loop surface area with power/IO traces to keep EMI and AC ripple on supply rails within tolerances.Going beyond that to squeeze IO interfaces between heatsink fins/CPU however seems a little extreme and very inconvenient since it would require the use of complex heat-spreaders or sticking the CPU between a top and bottom substrate which would be problematic for heat flow. Integrating signal traces in grooves under the heatsink would require precision alignment with the CPU, which may be a little too much for DIY, it would also make usage of thermal paste a lot trickier.So, I doubt using the heatsink as a signal carrier beyond complementary DC ground would be practical.[/citation]
Wait, are you saying that electricity flows easier through an aluminum heatsink than through the copper ground wires built into the die? I assure you that's not the case.