Need decent video card for Optiplex 980

[turuu]

i have a an Dell Optiplex 980
i7-870 CPU
8gb RAM
3 Hard Drives
with a standard Dell 305w PSU

What decent video card can i put on it?
i have 2 problems
1st is my CPU fan is awkwardly close to the GPU slot so the graphic card cant be bulky with a huge fan
2nd is my PSU is just 305w

i was thinking of buyin HD5670 or GT440
HD5670 requires minimum 400w PSU but not sure if it will fit
GT440 requires a minimum 300W or greater system power supply (with a minimum 12V current rating of 22A) which im not sure i have? but it fits in my PC very well

 

[turuu]

http://www.frys.com/product/6553053 will this card work on a Dell Standard 305w PSU?

 

[turuu]

people say even though HD5670 has minimum 400w PSU requirement, it will work on a 300w PSU perfectly.
How true is it?

 

[turuu]

My dell Optiplex 980 has a 12v on 15a, 305w PSU will ot be enough to power 3 sata hard drives and Geforce GT440 which requieres 300w PSU but needs 12v 22a
Please help i have to decide in a few days to buy or not to!!!!!