For the 6500 at least, working out the wattage for the PSU is easy because it doesn't have a screen!
Apple's docs suggest 220W. http://support.apple.com/kb/SP329
Of course, looking at the sticker on the PSU itself would be a more definitive answer!
Apple's docs suggest 220W. http://support.apple.com/kb/SP329
Of course, looking at the sticker on the PSU itself would be a more definitive answer!