Radeon HD 4870 System Requirements (from manufacturer's website):
PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard.
4X75 Watt 6-pin PCI Express power connector is required for CrossFireX™ system.
2X75 Watt 6-pin PCI Express power connector is required.
Certified power supplies are recommended. Please refer to:
http://support.amd.com/us/certified/power-supplies/Pages/listing.aspx
1024 MB Minimum of system memory.
Installation software requires CD-ROM drive.
DVD playback requires DVD drive.
Blu-ray™ / HD DVD playback requires Blu-ray / HD DVD drive.
For an AMD CrossFireX™ system, a second same AMD Radeon™ graphics card, an AMD CrossFireX™ Ready motherboard and one AMD CrossFireX Bridge Interconnect cable per graphics card (optional) are required.
500 Watt Power Supply is required.
600 WattPower Supply is recommended for CrossFireX™ System.