All of my brand name power supplies still work, but I can tell you that if you have a really old one - it is burning more power then it's worth (IE: 65-70% efficient is common) I use only 80-85% efficient power supplies now.
Antec 350 watts (10-12 years old) - on a shelf, works 100%
Antec 350 watts (7 years old) - in an old PC, works 100%
Antec 430 Earthwatts (4 years old) - in my HTPC case
Corsair 400 watts (3 years old) - in my Home Server
OCZ stealthXstream 600 watts (2 years old) - works 100%
Antec 750 Earthwatts (< 1 month old) - Just got this one
The funny thing is I tried to run those Antec 350's to death but just couldn't do it. I carried the oldest one from PC to PC, finally retiring it with 400+ watts of load on it 24/7 and it was blowing fast/blow-dryer hot air out of it and I just couldn't kill it. That is when I bought the OCZ 600 so it would run cool, quiet and save on the power bill
In my cabinet @ level 3 I have 13 servers. All of the servers there had 4-7 year old power supplies by Sparkle, Antec, and others. I have replaced about half of them - but only to upgrade to 80%+ efficient power supplies. Just replacing 5-6 of the supplies in the highest load servers allowed me to place a whole new server in (I was out of available AMPS). Replacing the other half will free me up for another server.
ADDED: Actually, I had one 2U Sparkle 400 watt server power supply die on me about 4 years ago. But that is the only "brand name" power supply I've had die that I can remember. Most of the dead ones I come across are $10-$20 garbage ones that come with cheap cases.Edited by LiquidKaos - 1/2/11 at 10:45am