Provided are an apparatus, system, and method to determine a cache line in a first memory device to be evicted for an incoming cache line in a second memory device. An incoming cache line is read from the second memory device. A plurality of cache lines in the first memory device are processed to determine an eviction cache line of the plurality of cache lines in the first memory device having a least number of bits that differ from corresponding bits in the incoming cache line. Bits from the incoming cache line that are different from the bits in the eviction cache line are written to the eviction cache line in the first memory device.