Embodiments of the present invention provide a system that performs a speculative writestream transaction. The system starts by receiving, at a home node, a writestream ordered (WSO) request to start a WSO transaction from a processing subsystem. The WSO request identifies a cache line to be written during the WSO transaction. The system then sends an acknowledge signal to the processing subsystem to enable the processing subsystem to proceed with the WSO transaction. During the WSO transaction, the system receives a second WSO request to start a WSO transaction. The second WSO request identifies the same cache line as to be written during the subsequent WSO transaction. In response to receiving the second WSO request, the system sends an abort signal to cause the processing subsystem to abort the WSO transaction.