ArchiCAD 15 System Requirements

System:
Windows® XP SP3
(32-bit and 64-bit)
Windows® Vista
(32-bit and 64-bit)
Windows® 7
(32-bit and 64-bit)
64-bit system is recommended
Note: ArchiCAD 15 was tested by Graphisoft on Microsoft Windows 7 Professional, Windows Vista Ultimate, and Windows XP Professional. Not tested editions differ in features that do not affect the correct functionality of ArchiCAD.
Mac OS X 10.6 Snow Leopard
Only case insensitive file-system volumes are supported.
Note: QuickTime 7 or later and Java 1.6.0 or later are required.
Note: ArchiCAD installer will automatically install QuickTime 7 and Java 1.6.12 if they are not present on your computer.
CPU:
Intel® Pentium 4, or compatible processors with equal or higher performance
Mac: Macintosh® with 64-bit Intel® processor (Core2Duo and later)

Multicore processor is recommended to exploit ArchiCAD 15 performance capabilities. Read more about multiprocessing.
RAM:
With 64-bit system: 3 GB RAM is required, 6 GB RAM or more is recommended.
With 32-bit system: 2 GB RAM is required, 4 GB or more is recommended.
The maximum amount of memory ArchiCAD can use on a 32-bit system is 4GB. Read more about this topic.
3 GB RAM is required, 6 GB RAM or more is recommended.
Hard Drive:

5 GB free disk space required for a full installation of ArchiCAD.
Additional 10 GB hard disk space required per project for work with complex models and 3D visualization.
Display:

1024x768 resolution is required
1280x1024 or higher is recommended
Video Card:
 True Color display adapter is needed.
Open GL and DirectX9 compatible graphic card with on-board video memory of 256 MB or more is recommended to fully exploit hardware acceleration capabilities.		 Open GL compatible graphic card with on-board video memory of 256 MB or more is recommended to fully exploit hardware acceleration capabilities.

You can find a list of recommended video cards at:

Recommended Video Cards for ArchiCAD 15

Requirements for BIM Server

System:
Windows® XP SP3 (32-bit and 64-bit)
Windows® Vista (32-bit and 64-bit)
Windows® 7 (32-bit and 64-bit)
Windows Server® 2003, 2008 (32-bit and 64-bit)
64-bit system is recommended
Note: The BIM Server for ArchiCAD 15 was tested by Graphisoft on Microsoft Windows 7 Professional, Windows Vista Ultimate, Windows XP Professional, Windows Server 2003 Standard Edition 64-bit, Windows Server 2008 Standard Edition 64-bit, and Windows Server 2008 R2 Standard Edition 64-bit. Not tested editions of the mentioned non server operating systems differ in features that do not affect the correct functionality of BIM Server.
Mac OS X 10.6 Snow Leopard (64-bit)

Mac OS X 10.6 Server (64-bit)
Only case insensitive file-system volumes are supported.

Note: Java 6 or later are required to run BIM Server. The installer will automatically install Java 6 (build 1.6.12) if it is not present on your computer.
CPU:
Intel® Pentium 4, or higher required
Mac: Macintosh® with 64-bit Intel® processor (Core2Duo and later)

Multicore processor is recommended Read more about multiprocessing.
RAM:

4 GB of RAM is required. 8 GB or more is recommended for complex models.
Read more about this topic
Hard Drive:

5 GB free disk space is required for the Graphisoft BIM Server installation. 10 GB of disk space (physically located on the server) is required per project.