Help figure out what Video card my PSU can handle

I am trying to figure out what graphics card I can get for my new PC that won't be a problem for my PSU. The PC is mostly for work and some video streaming. I do very little gaming, but the option to do so would be nice. I mostly need it so I can use 2 monitors for work.

I was looking at the GeForce GT 610 - http://www.newegg.com/Product/Product.aspx?Item=N82E168...
This says is requires a 300W PSU

I have also looked at the Radeon HD6570 - http://www.newegg.com/Product/Product.aspx?Item=14-127-...
This says a 400W PSU is required

I have been told that either card should run without a problem on my PSU which is only 220W. Is this true? What can happen if it draws too much power for my power supply to handle?



Here are the specs for the new PC:

- Dell Vostro 270s Small Form Factor - VOSTRO 270s, Windows 7 Professional SP1, 64-bit,
- 3rd generation Intel® Core™ i5-3450s processor (2.80GHz with Turbo Boost 2.0
up to 3.50GHz)
- 6GB DDR3 SDRAM, 1600MHz-1X4G+1X2G
1TB - 7200RPM, SATA 3.0Gb/s, 16MB Cache
Power cord, 220w, US


I would greatly appreciate any help