I've read a bit about 64 vs 32 bit for desktop machines but have been wondering a bit about it all lately. My hardware is a core 2 duo which supports 64 bit, nvidia pci-e and 4 Gb RAM (all about 3 months old). I'm running up to date CRUX 2.2 32 bit. I've been using the following pkgmk.conf export CFLAGS="-O2 -march=nocona -pipe" export CXXFLAGS="-O2 -march=nocona -pipe" And just about everything works fine (some weird firefox hanging problem but that's another story). I tried using: export CFLAGS="-O2 -march=x86-64 -pipe" export CXXFLAGS="-O2 -march=x86-64 -pipe" In pkgmk.conf and rebuilt bzip2 to test and it's actually faster (tested a large file) and it runs. So I got a bit more adventurous and tried compiling firefox and thunderbird with x86-64 CFLAGS and they seem to work too. Firefox (hanging seems to have stopped but I haven't tested fully) seems to run faster, rendering pages just seems faster than before. Has anyone else played with CFLAGS and 64 bit options? Because I'm using a 32 bit toolchain does it just ignore the x86-64 CFLAGS and resort to basic cpu flags? If so why would they be faster than nocona? Any thoughts? Ideally I'd like to run a pure 64 bit system but I'm not really that fussed. Thanks, Joe