Thermal Dissipation Power which is the theoretical maximum power a chip can consume. ACP on the other hand is sort of a typical amount of power consumed when running a typical server workload.
From AMD:
Q: What is ACP?
A: ACP is a metric that offers a relevant estimation of the power consumption of the Quad-Core AMD Opteron processors. ACP is determined by breaking down multiple components of power consumed within the processor, including the power dedicated to the cores, to the integrated memory controller, and to HyperTransport™ technology links. ACP and TDP are both indicators of processor power. TDP refers to the thermal design power processors are capable of consuming that is the specification system designers follow. AMD has referenced processor power consumption based off of TDP wattages to date. ACP reflects a relevant wattage that reflects power consumption while running server-class enterprise workloads. ACP is a useful metric for data center operators to use when estimating power budgets to size their datacenters. Thermal design power or TDP is more useful and relevant to system designers.
