A high-speed I/O trace is part of an I/O package architecture for an integrated circuit package substrate. The integrated circuit package substrate includes an integrated heat spreader footprint on a die-side and the I/O trace to couple with an IC device to be disposed inside the IHS footprint. The I/O trace includes a pin-out terminal outside the IHS footprint to couple to an IC device to be disposed outside the IHS footprint. The high-speed I/O trace can sustain a data flow rate from a processor in a range from 5 gigabits per second (Gb/s) to 40 Gb/s.