chipguy Wednesday, 05/18/11 01:34:24 AM Re: DavidA2 post# 101614 0 Post # of 149849 The core power cost of x86 over RISC depends on issue width, pipeline depth, and in-order vs OOOE. The front end decoder complexity goes up with the square of issue width for x86 vs roughly linear for RISC. OOOE is also more complex for x86 than RISC. For something like C2D/Nehalem/SB x86 probably adds 25-30% in power over an equivalent RISC. For something like Atom it probably adds 15-20% in power over an equivalent RISC. Now keep in mind for a 1W phone SoC the CPU core accounts for 300-400 mW. So x86 adds 45 - 80 mW in full active power when EVERYTHING ELSE IS EQUAL. Please note the qualifier. It is generally not true. In fact it is so not true that despite all its baggage x86 accounts for over 90 cents out of every dollar spent in the world on microprocessors of all size, description, and use.