Did you measure them under load (good) or everything disconnected (bad)? Some power supplies need some load in order to get the voltages within tolerance.

Some quality brands do use low quality capacitors. ZIPPY-EMACS is one of the greatest offenders of using some of the worst capacitors (despite a minority praising them as the best PSUs ever made). Delta will use TAICON for certain OEMs (which isn't good). I've seen AcBel use TEAPO on a few NetVista and PowerMac G5 PSUs.

Generally power supplies shouldn't gradually drop their voltage though. The 12v rail being ever so slightly under 12v is fine. It's bad PSUs that over-volt the 12v rail causing your HDDs to fry and other things (such as the ST Smooth chips on many Maxtors and WDs).

Anything within 5% tolerance on the +5V and +12V is within (ATX) specs (when loaded between minimum required load and maximum allowed load).

Also the voltage ripple should be less than 50mV on the 5V line and less than 120mV on the 12V line (these are measured at minimum load and maximum load conditions, but not without any load).

I recall having a power supply that refused to power on properly unless 1 or 2 hard drives were connected to draw at least minimum load from 5V and 12V lines. So try with 2 or 3 spare/expendable hard drives.

(Some hard drives require only 10% tolerance on 12V supply so they are much more forgiving, and they usually tolerate 100mV ripple on 5V and 200mV ripple on 12V. So you really can't break them with a normally working power supply, unless you disconnect a huge load on the fly so the voltages could have an overvoltage spike).

Has the power supply in question actually been in use or did it sit for many years? PSU's that see constant usage should only degrade if the capacitors are low quality or you are putting too much strain on the supply.

Without knowing the brand not a lot can really be said but generic power supplies are very very infamous for dropping the volts like this under load. If the volts are that low and no real load then it is really bad, some power supplies are bad enough to be fire hazards and have seen a few smokers before.

Thats a lot of info i wanted to know, thanks guys.
The Power supply was used constantly for around 5 years, plus it was in a house of cosntant smokers (golden nicotine tan).

I had some other PSU-s that I sold for cheap because of this, and because they appear often i started to wonder are they fixable easily.
I have one 500W power supply, i made a thread as well : Power Supply troubles

The problem with taht one is when its not loaded with anything it gives perfect 12V and 5V, but when loaded with something it turns on than instantly off.
And whats sad is that its a really quality 560W LiteON power supply 🙁

Stojke wrote:

Thats a lot of info i wanted to know, thanks guys. The Power supply was used constantly for around 5 years, plus it was in a hou […]
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Thats a lot of info i wanted to know, thanks guys.
The Power supply was used constantly for around 5 years, plus it was in a house of cosntant smokers (golden nicotine tan).

I had some other PSU-s that I sold for cheap because of this, and because they appear often i started to wonder are they fixable easily.
I have one 500W power supply, i made a thread as well : Power Supply troubles

The problem with taht one is when its not loaded with anything it gives perfect 12V and 5V, but when loaded with something it turns on than instantly off.
And whats sad is that its a really quality 560W LiteON power supply 🙁

Give Seasonic power supplies a try then you won't go back to using anything else.

Id gladly buy a 250 euro power supply, if i had 250 euro 😀

The S12-II is only about €50 😉

Still too expensive. Average pay is 200 euro a month here. So youre either outta of here or a mobster