Here are the main specs from ATI.
ATI Radeon HD 4850 System Requirements:
- PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard
- 450 Watt or greater power supply with 75 Watt 6-pin PCI Express® power connector recommended (550 Watt and two 6-pin connectors for ATI CrossFireX™ technology in dual mode)
- Certified power supplies are recommended. Refer to http://ati.amd.com/certifiedPSU
for a list of Certified products
Doesn't mention Ampage ;-( check the box your card came in.