At its CES press conference, Intel boldly announced the availability of a new line of Ivy Bridge processors that dropped power usage down to an impressive 7 watts. They claimed to have beaten their own estimates of delivering a 10 watt ultra-low voltage processor, and everyone was happy--this meant better battery life and thinner laptop shells for systems released in the spring of 2013, before the next generation of Haswell chips arrives in summer. Turns out Intel fudged the numbers a bit. That 7 watt figure would normally be a processor's thermal design power (TDP), or the maximum amount of cooling a system needs to be able to do to keep the processor from overheating and eventually going all melty. This time, Intel was actually bragging about SDP.
What's SDP? It stands for scenario design power. So here are the facts about the new Ivy Bridge processors that will soon be gracing lightweight laptops: they boast a TDP of 13 watts, not 7, which is still significantly lower than the previous 17 watts but not quite as amazing as Intel made out. Intel publicized the 7 watt figure because it made for good publicity, but SDP is actually a significant measurement that we'll probably see more of in the future. These chips will lead to thinner and more power efficient convertibles and Ultrabooks.
Ars Technica talked to Intel to suss out all the details about SDP and the new Ivy Bridge chips and put together a detailed explanation of what this means for computers. Though TDP is meant to represent the maximum amount of heat a system needs to be able to dissipate, Intel's chips can and do exceed TDP in some cases--for good reason. Using Turbo Boost, Intel chips can briefly rocket past their intended max clock speeds and TDPs to do a short bit of work very quickly, then step back to idle power usage. This is called a power level state. OEMs can control how hot and fast the chip is allowed to get, which is why some laptops are faster than others when using the same processors.
Intel's added some new power level states to these Ivy Bridge processors that dip below the baseline TDP: 10 watts and 7 watts, which is where the "scenario design power" comes in. According to Ars, the number will mostly matter under sustained load:
"Short bursts of CPU activity will run equally quickly on a Core i5-3339Y whether the PC OEM sets its PL1 value to the SDP of 7 watts or the full TDP of 13 watts, but for long-running CPU-heavy activities like gaming and video encoding there's a chance that two different PCs running the same processor may perform the same task at different speeds."
SDP is yet another metric we'll have to keep in mind when poring over spec sheets and evaluating laptop performance, but Intel is, at least, committed to cutting power usage wherever and however it can. All-day battery life in a Core system is so close we can taste it.