64-bit mainstream desktop computing was introduced around 2003 with AMD’s Opteron and Athlon 64 processor lines. These processor’s were based on AMD’s 64-bit extensions (x86_64) to Intel’s 32-bit (x86) architecture. Apple also started selling the 64-bit capable G5 systems. Intel adopted AMD’s specifications and introduced a few compatible processors before ultimately releasing their own 64-bit extensions. Intel also has the Itanium 64-bit (IA-64) architecture which is completely distinct from either x86 or x86_64. Nearly all new computers sold now will have a 64-bit architecture and operating system. Over the years, AMD and Intel have introduced different brand names and code names and it can get confusing. These are 64-bit capable:

AMD “x86-64″, “AMD64″, “x64″

• AMD Athlon 64
• AMD Athlon 64 X2
• AMD Athlon 64 FX
• AMD Athlon II (X2/X3/X4)¹
• AMD Opteron
• AMD Turion 64
• AMD Turion 64 X2
• AMD Sempron (“Palermo” E6 stepping and all “Manila” models)
• AMD Phenom (X2/X3/X4)
• AMD Phenom II (X2/X3/X4)

Intel “IA-32e”, “EM64T”, “Intel 64″

• Netburst family
• some Celeron D’s: LGA 775 “Prescott” models
• some Pentium 4′s: “Prescott 2M,” “Irwindale” “Cedar Mill”
• Pentium D
• Pentium Extreme Edition
• Intel Core
• some Xeon: since “Woodcrest”
• some Core 2: since “Merom”
• Dual Core: E2140, E2160, E2180, E2200, E2220, E5200, E5300, E5400, E6300, E6500, T2310, T2330, T2370, T2390, and T3200
• Celeron: Celeron 4×0; Celeron M 5xx; E3200, E3300, E3400
• Intel Nehalem
• Core i3
• Core i5
• Core i7
• Intel Atom

¹The X2/X3/X4 refers the number of cores.