I don't like charts like that. Back in the day when video cards didn't require as much power as they do today, you really didn't need to worry about the amps on 12V rails, you could go by the PSU's overall wattage to gauge what you needed.
Now it's much different and PSU manufactureres are quite different as well. A 500W Joe Blow brand may have 18A on multiple 12V rails while a PC Power & Cooling has 35A on one 12V rail. That's quite a difference in design respects and power distribution.
Amps are really what are power the card.
Volts x Amps = Watts
When you see Watts on a PSU raiting, that's all the rails (3.3V, 5V, 12V) put together. You need to dig further to see the Amps that are available on the 12V rail to properly power your card. If it's under powered you'll either have game shut downs on you, damange done to the card, or it may not even display video out during boot up.