Official Diablo III System Requirements

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Wonder what it will take to play Diablo 3? No worries! We have the recommended settings and minimum settings to play the game as well as single player system requirements and multiplayer system requirements and options!

RECOMMENDED SYSTEM REQUIREMENTS

Windows

Windows® Vista/7 (latest service packs)
Intel® Core 2 Duo 2.4 GHz or AMD Athlon™ 64 X2 5600+ 2.8 GHz
2 GB RAM
NVIDIA® GeForce® 260 or ATI Radeon™ HD 4870 or better


Mac

Mac® OS X 10.7.x or newer
Intel® Core 2 Duo
2 GB RAM
NVIDIA® GeForce® GT 330M or ATI Radeon™ HD 4670 or better


MINIMUM SYSTEM REQUIREMENTS

Windows

Windows® XP/Vista/7 (latest service packs) with DX 9.0c
Intel Pentium® D 2.8 GHz or AMD Athlon™ 64 X2 4400+
NVIDIA® GeForce® 7800 GT or ATI Radeon™ X1950 Pro or better
1 GB RAM (XP), 1.5 GB (Vista/7)
12 GB available HD space
DVD-ROM (required for retail disc versions only)
Broadband* Internet connection
1024x748 minimum resolution


Mac

Mac® OS X 10.6.8, 10.7.x or newer
Intel® Core 2 Duo
NVIDIA® GeForce® 8600M GT or ATI Radeon™ HD 2600 or better
2 GB RAM
12 GB available HD space
DVD-ROM (required for retail disc versions only)
Broadband* Internet connection
1024x768 minimum resolution


Source:

http://us.battle.net/support/en/article/diablo-iii-system-requirements