Oops, changed to 'horde'! The distinction is mostly architectural, in that the 'horde' is composed of an undifferentiated mass of CPUs (currently 8, could probably be expanded up to 128 with a cache-based memory hierarchy, which would certainly feel more 'horde-like'). The application processors can be accessed individually, whereas the horde can only be accessed as a group.
Generally things hoarded are sequestered on a shelf against some imagined future need instead of put into service. At the same time, a "horde" usually numbers more than 8, except when treated ironically, after the manner of "three's a crowd". So I would suggest "horde", or "crowd". 8 is just a bit thin even for a crowd, unless it concerns a certain president's inauguration attendance.