Upgrading power

[backdrop001]

hi guys i'd like to upgrade my power to a modular power unit but not sure what compatible with my system or what type i need.

I have a Asus esention the model is : cm680-us-3ac

the one that is in it is only 300 watts so i'd really like to upgrade that so i can get a better video card.

 

[chimera201]

list ur current or would-be system components

 

[backdrop001]

Intel Core i7 3770(3.40GHz)
• 8GB DDR3 2TB HDD Capacity
• Nvidia Geforce GT 545 3GB DDR3
• Windows 7 Home Premium 64-Bit
Intel H77 motherboard



here's a link to the one i have it show further specs if you need more infor.