A computer that is used as support, still consumes power as if it is a standalone weapon in addition to being part of the main weapon.
{F22743, size=full}
2 more issues/cases that points to it being used as a standalone weapon still for power consumption:
# removing the support computer before unlinking it, does not remove its standalone power consumption.
# adding more support blocks than main ones, still adds consumption and it's definitely standalone consumption that gets added only.