Since some of our readers didn't actually believe that their bellowed R600XT might need a 750W or higher PSU, here is some proof. AMD clearly states that you need a 750W or better power supply for this hot beast. You also need an Athlon or Pentium 4 or better CPU, 512MB for it to work and 1024MB for optimal performance, or more. You can read the original part here.
The card supports Windows XP, 2000 and Vista both 32 and 64 bit versions. We still have hope that the card might work with a good 500W PSU, but this is what AMD recommends. Well, it's all here.
Update: We still stay behind the picture we posted, but several sources close to AMD, partners and retailers who has had cards confirmed that a single Radeon HD 2900 XT works with a good quality 450 - 500W PSU as well. One of the sources confirmed the slide we posted, but said that this is actually the Crossfire Radeon HD 2900XT with a Quad core CPU requirements. Some of our friends will test the card for us and we will let you know if it works with a 500W PSU. Stay tuned. Gibbo from Overclockers has tested his card and he said it will run with 400-500W PSU and you can read about it here.