Now even if the powersource is 5 years old,
if the PSU is 5 yrs old it NEEDS to be replaced!!!!!!!!!!!!!!! best advice is to replace every 2-3 yrs, after that you enter the aging danger zone.
power supplies lose output ability over time, upto 30% in an average of 3 yrs. meaning a 500W 3-5yr later may only be a 350W supply. and likewise for the AMP output. if it was a 40A it may now only be 28A.
there are certain variables to this including but not limited to, quality of the PSU and how much the PSU is run at peak power.
500 watts is a rating thats given for something like 80% capacity due to temperature. The actualy device might be a 550watt or so, lol.
no. please go do some research on PSUs and how they operate before you give advice.
the power rating has nothing to do with x capacity due to heat. a 500w PSU will put out 500W however most power supply companies rate the PSU wattage at PEAK power which is the max amount of power it will put out. some companies like PC Power & Cooling rate PSU at CONTINUOUS power (the amount of power used in normal operation) you will hit peak power depending on the system config and what you are doing such as extreme gaming or other graphics work.
your thinking about the efficieny rating, if a PSU is rated 80% efficient it merely means that 80% of the power coming into the PSU from the wall will be coverted to watts and then amps for power out put. the remaining 20% is lost to heat in the process. It has NOTHING to do with the wattage rating of the PSU. another factor of the efficiency rating is the temp it is rated at. a PSU rated 80% efficient at 25C is garbage because your PSU will be above 25C 10 seconds after power on. what you want to look for is an efficiency rating that was taken at 40-50C which is the average operating temp of a PSU.
the efficiency of a PSU can come in to play for the life of the PSU and how soon it loses output ability, as well the size of the PSU can play also. if you have a low efficiency PSU it will run hotter, likewise running a PSU that is just barely large enough for your system can hurt in the long run. yes it will run the system now, BUT, if you do a lot of extreme stuff and run that PSU at PEAK or close to peak power a lot it will run hotter.
all that heat will speed up the pace at which the PSU loses output ability.
the best advice is to run a PSU a little larger than you need. such as if you NEED 500W 35A, run something like 650W 40A+, this will allow you to stay out of peak power more and keep heat down. which in turn will slow the rate that the PSU dies (loses power output)
the PSU is the most important component. run one too small or too old and you WILL eventually fry components due to lack of power.