Is this enough power?

Always get 2x what you think you'll need, never how little....

He means your better off to get more power than you need than to try and get just enough. The 5770's If I remember corectly have a lower power consumption than say the 4XXX series. So I would think a 1000w or 1200 would be more than enough, You need to keep in mind it's not the wattage as much as the Amps on the 12v rail(s) that matters. According to this review the 5770 draws 102w under load Ati Radeon HD 5770 reviewed: DirectX 11 Mid-Range - Radeon HD 5770, Test, Review, DirectX 11, Benchmark, Graphics Card - PC Games Hardware

The 1000w power supply appears that it will do the job. 80 amps And has enough PCI-e connectors as well. Komplett.no - Cooler Master Silent Pro M1000, 1000W

It should have. :)

Here is a snip

Then your good to go, right? Nice system by the way. IMO the power supply is the core of your system and should always be the best you can afford. You also have to take into consideration powering the board, fans, hard drives and optical drives. So I wouldn't go less than 1000w. Why take any chances. That's not to say you can't find a cheaper 1000w power supply, but going with a proven brand is the safest. Why risk all your hardware on an inadequate or poorly made one.JMO Fabe

Hemulen said:

The 5770 uses only 1 PCI-E power connector.

True. But you also state:

Hemulen said:

As you can see, I'm gonna run 3 x 5770 cards, and I have a 1000W power supply.

Each card will require a separate PCI-E power connector, hence you will require 3 in total.