An Intel Core 2 Duo E8400 CPU is required at a minimum to run Sid Meier's Civilization® IV. Sid Meier's Civilization® IV system requirements state that you will need at least 4 GB of RAM. The cheapest graphics card you can play it on is an NVIDIA GeForce 510.
Sid Meier's Civilization IV will run on PC system with and upwards. Additionally it has a Mac version.
Note
It is very important that you ensure that you are using the latest drivers and versions of all of your software. While doing this you might encounter some specific conflicts with the minimum specifications for Civ4.
For example, if you have an ATI video card and you are using Windows XP you must (it says recommends but when problems are present and no solutions present themselves it is sometimes necessary to make recommended a requirement) have Service Pack 2 installed to meet the requirements of the ATI driver.
Minimum System Requirements
CPU
Intel chipset
RAM
(VRam): 128 MB RAM
OS
OSX 10.7.5 or newer
Graphics Card
(ATI): Radeon 9600 Video Card (NVidia): GeForce FX 5200
HDD Space
3.5 GB free disk space
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