Is this PSU good enough for Radeon HD 6770?

YES and YES, although it would of been nice to know what the rest of your system is so i could work out your power requirements more accurately.

Yes

For a system using a single Radeon HD 6770 graphics card AMD specifies a minimum of a 450 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 26 Amps or greater and have at least one 6-pin PCI Express supplementary power connector.

For a system using two Radeon HD 6770 graphics cards in 2-way CrossFireX mode AMD specifies a minimum of an 600 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 36 Amps or greater and have at least two 6-pin PCI Express supplementary power connectors.

Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Total Continuous Amperage Available on the +12V Rail(s) is the most important factor.

The Antec Neo Eco 450C, with its combined +12 Volt continuous current rating of 34 Amps and with one 6-pin PCI Express supplementary power connector, is sufficient to power your system configuration with a single Radeon HD 6770 only.

An old PS3 power cable should work.

My CPU : http://ncix.com/products/?sku=46281&promoid=1101

Motherboard: http://ncix.com/products/?sku=52677&promoid=1205

RAM: http://ncix.com/products/?sku=55546&promoid=1101

And thank you guys for all the responses! Need any more specs?

PS3 power cable?
Probably, provided it fits snugly. On the other hand power cords are $4 so I'd recommend ordering one with your Power Supply: http://us.ncix.com/products/?sku=3104

(so your PS3 isn't being used?)

POWER SUPPLY:
Yes. It will work. It provides 34Amps on the +12V rail.

But doesn't it need 36Amps?
No. I keep seeing Amps incorrectly stated, so let's clear it up.

Energy equation:
Watts = Amps X Voltage (DC)

We know that the Voltage is 12V. If the card required 36Amps then we'd need 432Watts just for the graphics card which isn't even close.

Now here's a power graph:
http://www.tweaktown.com/reviews/4099/sapphire_radeon_h...

Note that the ENTIRE system is drawing 263Watts. Since I usually recommend builders aim for about 50% to 60% of the max PSU Wattage under load your bang on!

Update:
My guess is graphics card manufacturers are incorrectly stating an AMPERAGE for the entire system, not the card. It's frustrating and common. They need to state the PSU's maximum Wattage AND the minimum Amp value on the +12V rail because PSU's vary.

If you can find the LOAD WATTAGE (at benchmarks) for the graphics card then divide by 12 and compare to the PSU +12V rail value which needs to be higher.

An easy way is to look at MAX LOAD in a 2xCrossfire vs single card configuration. The difference is the LOAD WATTAGE of a single card.

Power Supplies:
A 500Watt power supply comprises several different voltage outputs. The 500Watt value is created by ADDING up the power each voltage output could generate if ONLY it was creating power. It's impossible to actually output 500Watts.

So the +12V rail has a maximum power output it can provide (rated in Amps) for the graphics card.

It's easy to find two DIFFERENT 500Watt PSU's with one providing sufficient power for a particular graphics card and the other not.

Thank you for the information. Then I suppose I'll go with this build? It's look likely for me.

And about the PS3 power cord, looks like a computer power cord pretty much exact similar. I actually have 2 PS3's, but one of them died, I still have it though and all of it's cords, the power cord should be working just fine, it's collecting dust  

I see no issues. I still recommend spending $4 on the cable. I had two different PSU cables and one was loose and the other fit fine.

Sell the broken PS3?
I'm in Canada, but I'd buy your broken PS3 for $50 if you wish to sell it. I can't offer more because the Warranty is expired and it's too expensive to fix. As a technician I simply want to tear it down for fun.

Cheers.

I also live in Canada. It's completely fried, it got the "Yellow Light", so I just bought a slim after that and have been using it since.

Hmmmm..