The invention provides a cache architecture that selectively powered-up a
portion of data array in a pipelined cache architecture. A tag array is
first powered-up, but the data array is not powered-up during this time,
to determine whether there is a tag hit from the decoded index address
comparing to the tag compare data. If there is a tag hit, during a later
time, a data array is then powered-up at that time to enable a cache line
which corresponds with the tag hit for placing onto a data bus. The power
consumed by the tag represents a fraction of the power consumed by the
data array. A significant power is conserved during the time in which the
tag array is assessing whether a tag hit occurs while the data array is
not powered-on at this point.