How to check if a processor is capable of 64-bit.

If you are running Linux, open the terminal prompt and run:

grep --color=always -iw lm /proc/cpuinfo

If this command returns lm (Long Mode) as one of the flags, then your processor is capable of 64-bit.

flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt