e c'era qualche pirla che diceva avrebbe superato i 245 W solo guardandone i 
connettori
altra cosa da notare è che anche se la gpu va a consumare meno, si rimane 
sui 225W, quindi non dipende dalla gpu in se


ATI will introduce three Radeon HD 2900 cards on the 14th of May. According 
to a document we've seen the most powerful one is called the Radeon HD 2900 
XT 1024MB DDR4. Its TDP, thermal design power of the GPU, is an astonishing 
180 Watts, while the whole board dissipates 225 Watts.

The second card is the Radeon HD 2900 XT 512 MB GDDR3 and its GPU's TDP is 
160W due to slightly lower clock speed and the whole board again dissipates 
225 Watts.

The third and final card is the Radeon HD 2900 XL, a cheaper version of the 
marchitecture with 512 MB GDDR3 and its GPU will dissipate 130 Watts, while 
the board will dissipate 205 Watts. We believe that the power components on 
the card gets really hot, 82 degrees C on the outside of the cooler is what 
we've already seen.

http://www.fudzilla.com/index.php?option=com_content&task=view&id=850&Itemid=1