AMD and Intel have put in a lot of time and effort devising CPU power management schemes for their multicore devices aimed at trimming the energy draw of the server farm. But new questions are being raised as to whether these techniques are the most effective means to lower energy bills, particularly as virtualization becomes more popular throughout the enterprise. Both AMD and Intel use some form of on-chip processing to shut down idle cores, allowing energy to be diverted elsewhere. Intel's platform provides for individual control of processors — ostensibly to preserve laptop battery life — and it is tying it to a server power management system that allows admins to direct power within individual server racks. But according to some critics, enterprises shouldn't expect much from the on-chip power-saving tools, particularly those that seek to manage idle cores.