I am just wondering how all you guys PSU are doing, have they lasted long?
Have you had to replace them ever? If so how long?
I just wonder thats all, because I bought some PC parts and I might get a PSU later if its really necessary, so far I dont think I had a problem though.
i had my old psu for about 3.5 years and it started making loads of noise. had this one for about 1 year and it is already less then perfect. i think ultimately, the more you spend the longer it will last. mine were both cheap and chearful. but 3.5 years isn’t bad going for £20…
Its basically depend on use.Some time ,for some user it will work continuously for 3 to 4 years and for some user it will not work more than a year.
I have some that still work that were purchased over 15 years ago. I have had about three fail in the last 15 years - at least one of those was due to a lightning strike.
A good PSU will last a long time. You should make sure your current PSU provides enough power for your new components. You wouldn’t want to take a cheap-o 150W PSU out of a Dell box and put it in a custom computer with a quad core processor and high end GPU. It wouldn’t even power up.
I have a 12 year old Compaq that still works fine, but admittedly it hasn’t been used frequently for many years now. I also put together a PC 3 years go and I had used ULTRA PSU (I believe 600watt) which went bad only after couple of years of use. I think it depends on the work load, power settings, and where you store your PC will also have big influence how well your hardwares cope over time. I put together a brand new desktop 6 months ago for my garage, from fans to cd roms things started to go bad. I think the breakdown had a lot to do with moisture, drastic temp difference between day and night, and dusts building up overtime.
I would say it wouldn’t be unusual to have a PSU which lasts 15 years, they are generally among the most “trustworthy” components within a computer and their relatively simple compared to the other parts which gives them the advantage of fewer things to go wrong, however problems can occur, i’ve had a few blowouts which didn’t last past their 2nd birthday so it’s really down to luck. Dust, moisture and heat can reduce the lifespan though. 
I had a PSU die on me, and then almost another one, that, well, I’m not going to jix the fates