No, they do not. Power supplies can vary from style or model. Before you choose a right power supply for your system, you need to gather the following information:
a. What is your case form-factor? AT, ATX or Micro-ATX.
b. What is the wattage requirement on your system? 200W, 250W, 300W or more.
c. What type of chassis do you want to use? Rackmount (1U, 2U, or 4U), tower, or pedestal.
d. Do you want redundancy or not? Dual redundant, tripple redundant or none.