Depends on program actually and what version of ICC. What you're describing was old ICC behavior before they were sued. My own tests compiling Povray with ICC 13 I've found that the ICC dispatch code does work properly on my FX 8350. In other words, compile with AVX dispatch support and the program will choose the AVX code path, which gives the same performance as compiling with only AVX support (the dispatched program also runs on my PhenomII 1090T, but the AVX exclusive program doesn't). But that doesn't necessarily mean the ICC code is always faster. Sometimes GCC code is faster because GCC can explicitly order instructions for Bulldozer, but it doesn't do autodispatch. That has to be coded separatley by the programmer.