Can a 20 pin connector be plugged into a 24 pin mobo?

[Digi7aliZed]

Hi, there. My friend is giving me a free used 600w PSU which he tested with a PSU meter, and it ran fine. However, it has a 20 pin connector and my motherboard has a 24 pin slot. I really need a better PSU as my current one is 300w.

Bottom line is, will it be smart/safe to use it?

(By the way, the card I'm getting needs a direct power cord. It's a 6870)

 

[kevin83]

It will work, but it is not smart as the extra pins are used to deliver more power to the motherboard. What is the exact model of the psu?