Yesterday Intel announced details of their 22nm silicon process. There were a number of fascinating details on how the transistors are made, but one graph from the presentation presages what will happen in the mobile market over the next several years.
 |
As the voltage goes to zero, the consumed current goes to zero. It sounds obvious, but really isn't. Even when nominally "off," transistors have always leaked current into the substrate. As silicon features have gotten smaller the power they consume while active has declined rapidly, but the leakage current less rapidly. Other graphs in the presentation show a tradeoff between operating voltage and leakage current, which means power consumed while active versus power consumed at all times. Intel's production chips will likely tolerate a little leakage to get lower voltage, but still very low. |
In 32nm silicon processes leakage current may already be the primary factor in power consumption. It is difficult to estimate how serious the effect is, but this article from March 2008 shows leakage current as relatively insignificant in 180 nm silicon but growing to nearly 40% of total power consumption in a 50 nm process. We're at 32nm now.
Except Intel just changed the game.
ARM has several advantages in the mobile space. Their products are available from many manufacturers and their support in software toolchains is nearly universal, but their biggest advantage has been low power consumption compared to x86 or other architectures. ARM did a great job designing chips which are very sparing of the power they consume while operating.
Except Intel just changed the game.
Intel now has a silicon process with radically lower leakage current. x86 consumes more power while actively operating, but leakage current is more significant. ARM's competitive advantage has shrunk substantially. Expect to see a lot more x86 CPUs in mobile devices, starting in late 2011.