AMD has lost a fair amount of ground in the server space over the past little while, but it's gearing up for a comeback with 32-nm Bulldozer processors—and it has some new tricks up its sleeve to woo server users. AMD has announced on its blog that upcoming, Bulldozer-based Opterons will let users manually adjust thermal envelopes in 1W increments. AMD's John Fruehe explains:
With today’s AMD Power Cap Manager, you can limit the processor P-states and cut power consumption although this limits the processor’s ability to get to the top frequency (which is also the most power-hungry spot on the curve as you can imagine…). By essentially “locking out” the top P-state, the processor never gets into that state, even under heavy utilization, helping cut down total power to the processor.
With the new TDP Power Cap for AMD Opteron™ processors based on the upcoming “Bulldozer” core, customers will be able to set TDP power limits in 1 watt increments. This means that instead of having to choose between different TDPs for processors, you can actually buy any power range and then modulate down.
Fruehe points to an eWeek story that provides some more details. According to that story, users will be able to reduce TDPs (not raise them) and "tweak the frequency of the cores as needed to get the maximum amount of performance allowed under the TDP setting." It's not clear exactly how much granularity will be available, but Fruehe says the CPU will be able to hit its maximum frequency even with a capped TDP, provided the workload it's running doesn't push power consumption over the limit. I'm guessing the feature will tie in with AMD's next-gen Turbo Core implementation, which is due to premiere in the first wave of Bulldozer chips.