POWER SHARING BY MULTIPLE EXPANSION CARDS

A first printed circuit board (PCB) comprises a first hardware interface, compatible with an interface standard, to couple the first PCB to a first socket of a second PCB, which further comprises a second socket, and first and second busses respectively coupled to the first and second sockets. The first PCB comprises a second hardware interface to communicate a first signal, to indicate a total current drawn by multiple PCBs, and a second signal each with a third PCB while the third PCB is coupled to the second PCB at the second socket. The first PCB comprises circuitry to impose a limit on power consumption by the first PCB, circuitry to generate, with the third PCB, the first signal, and circuitry to generate a second signal, which is to provide, for each of the multiple PCBs, an indication of whether respective circuitry of the PCB is to be throttled.