Ocre wrote:
the medfield i heard of has a terrible idle to light cpu power draw.
RWT Article wrote:
It is manufactured on Intel’s 32nm SoC process that has been optimized for power efficiency. The process includes three transistor libraries for performance logic, standard logic and always-on blocks and extremely dense SRAM macros. As an example of a new process technology optimization, the 32nm SoC process includes a transistor that has 10X lower leakage than any available at the 45nm node, which is crucial for always-on regions. In addition, the process has both 1.8V and 3.3V I/O transistors, which are necessary for integrating all the I/O into the SoC.
RWT Article wrote:
The branch predictor is an 8K entry Gshare predictor, twice the size of the previous generation. The 48B post-fetch instruction buffer in Lincroft has been augmented to act as a cache to save power by eliminating repeated instruction fetches in Saltwell. This technique is similar to the Loop Stream Detector that was first implemented in Merom.
RWT Article wrote:
An always-on TSC and local APIC timer have been added, primarily to assist with power management and avoid waking up the CPU.
RWT Article wrote:
One of the major power improvements in the design was moving the L2 cache to a separate voltage rail from the CPU core. The 6T SRAM in the L2 cache has a significantly higher minimum operating voltage compared to the logic and 8T SRAM cells used in the CPU core. The Vmin for the Saltwell core is 0.7V, while the L2 operates on a fixed 1.05V rail. Intel’s engineers estimate that using separate voltage rails improved the Vmin by around 18mV.
RWT Article wrote:
The clock distribution was also improved to reduce power, with finer-grained frequencies. ... The PLL, which generates the core clock, was also tweaked for lower dynamic power consumption.
RWT Article wrote:
The net result of the 32nm process technology and circuit design improvements is significant. Figure 1 shows the projected power for the 32nm Saltwell core and L2 cache at a number of operating points. As a rough comparison, it consumes about 40% less power at a given frequency, compared to the previous generation Z600 core.
