Do I need more watts ?

[fathurriza7]

if my pc just requires <450w. whats the different when I use 500w psu and 750w psu. is the 750w psu will increase my electric bill even my pc just requires <450w?

 

[turkey3_scratch]

What are your specs?

 

[R_1]

no the unit, say a 750W, can deliver 750W if needed to, the system is not constantly consuming the total rated power.
A 500W unit that is 85% efficient will be using 575W from the wall to give the system 500W DC power.

if the system needs 300W, the 750W will provide the 300W.

 

[turkey3_scratch]

A 500W unit that is 85% efficient will be using 575W from the wall to give the system 500W DC power.

Actually it would be 588W, not 575W. Remember the equation is:

efficiency = DC / AC

So in this case we move AC over and divide by effiiciency to get:

AC = DC / efficiency

 

[R_1]

A 500W unit that is 85% efficient will be using 575W from the wall to give the system 500W DC power.

Actually it would be 588W, not 575W. Remember the equation is:

efficiency = DC / AC

So in this case we move AC over and divide by effiiciency to get:

AC = DC / efficiency

thanks.
the point being you will always consume more than what is needed by the actual parts. how much will depend on the efficiency of the PSU. you still have to pay for the efficiency.