H4X3R :
how? 350 is about 70% of the total power it can deliver, so there should be no problem (with a decent power supply)
Most power supplies ramp up pretty heavily above about 50% load.
You can run a good power supply at 70% or 80% load, but it will generally be loud and you may reduce its life.
Many cheap power supplies won't run at 70% load consistently and often don't have a rating on the combined 12V rails that you would expect from a good power supply.
If people are putting a video card in an existing system, you might compromise on a PSU loaded to 70% providing it is not cheap and nasty (e.g. Shaw).
When buying a new power supply however, they are much better off in the long run buying something a little more powerful in a good brand.
A good quality 650W power supply is perfect for this system if it is not overclocked (beyond the factory GPU overclock).