While a programmed RCB value can be used by the user application to compute the maximum number of completions returned for a request, most high performance memory controllers have the optional feature to combine RCB-sized completions in response to large read requests (read lengths multiples of RCB value), into completions that are at or near the programmed Max_Payload_Size value for the link. You are encouraged to take advantage of this feature, if supported, by a memory controller on the host CPU. Data exchange based on completions that are integer multiples (>1) of RCB value results in greater PCI Express interface usage and payload efficiency, as well as, more efficient use of completion space in the Endpoint receiver.