It depends on your hardware (motherboard expansion slots) as well as your power supply.
If this is an off the shelf type PC (Dell Optiplex, etc...) post the model number, we can look it up for you.
If not, you can obtain the Mobo info from utilities (like CPU-Z) but the power supply has to be documented, or physically looked at.
You can locate CPU-Z at the URL below:
CPU-Z