Phenom II 940 and 920 are socket AM2+, work only in AM2+ motherboards and only with DDR2 memory. 945 and 925 are AM3, work in either AM2+ motherboards with DDR2 memory or AM3 motherboards with DDR3 memory. Yes, models ending with 5 have both DDR2 and DDR3 controller (or in fact one controller working in two modes).