You can determine precisely what power is required for your current or future PC in both watts and 12v rail amps from the link below. Yes a PSU that is four years old could show a loss in total capacity with capacitor aging. The info. at the link below is objective and accurate and will tell you if your current PSU is satisfactory or not and if not what PSUs will serve you well. No guessing required!
I totally agree with beenthere - capacitors in switching power supplies are some of the most stressed components. If I were putting a substantial amount of money into a new build - I would also get a new quality PSU.
hm ok. Is it safe if there are problems? like would it damage components or? I guess if it powers off randomly (not a power cut) best to get higher wattage?
I agree with rolli59's recommendations. Stay with your current PSU.
As with all components, electrical, mechanical, or otherwise. sooner or later they will fail. When that day comes, you can consider buying a new PSU 650 watts or higher. Until that day, your present PSU will serve you well.
Yes, which is why some of us said to go new. It may last for another 4 years - are you willing to bet your mobo/cpu? Many times a PSU will die gracefully - I've also seen it take out almost everything in the case.
Originally I was never going to but I was worried that it could damage parts (which I have experienced in the past). If it starts to fail, shut down - new buy? could failure cause damage?
It is all based on the quality of the unit, yours has good safeties in place "Full Range Input with Complete Protection (OVP;OCP;SCP)" which is the reason to buy a quality PSU in the first place so if problems then only the PSU that gets affected.