If the below produces lm (long mode) flags, then the cpu has support for x86_64 architecture.
# grep lm /proc/cpuinfoI have seen quite a few dedicated servers with support for x86_64 architecture, but i386 installed instead.
When doing a `uname -a`, the output misleads you to think that x86_64 is not supported. Such machines do not fully utilize the hardware resources and decreases performance of you box.