Both are Socket 939, which is good. If you like to overclock, go with the Opteron 154, since the Venus core is basically a enhanced San Diego core (provided that you don't get the CABGE "Cabbage" core) with an improved memory controller. It'll be a tad bit slower when it comes to gaming, but it'll own the FX-57 at number crunching anyday. Also, you can overclock the Venus core extremely high with air cooling and barely any raise in voltage. One thing the FX-57 has though, is the unlocked multipliers, which means that you can unlock them and get some pretty decent overclocking out of it (although it's nothing compared to the Opterons).