Voltage tolerances

Crunchie

What sort of voltage tolerances are acceptable as in low/high? I've got a fairly new FSP-AX500 (Blue Storm) that is showing a low 12v level. Fluctuates between 11.68v and 11.8v. The 3v and 5v also are a little low but ok imo.
The low 12v has only occurred since moving into the Thermaltake case running 5 case fans on top of the cpu fan and the gpu fan.
Could this be a case of too much of a drain on the 12v rail? Or would the psu be dying? It's only about 6 months old.

madmat

The ATX spec is +/- 5% so for 3.3V it's +/- .17V for 5.0V it's +/- .25V and for 12V it's +/- .60V.

Now remember it can be low or high within this range and be in spec.

Crunchie

So, theoretically, the 12v can go as low as 12.4 and still be viable? Cool .

GHoosdum

Theoretically, you're still OK if the 12V droops to 11.4. That's a range to be careful in, though. At that point, I'd start being careful about adding any drives or doing any OCing.

Crunchie

Here's me thinking that the PSU I bought would be more than enough . Would a dual rail PSU be better for running all the fans etc that I have?

GHoosdum

Nah, the dual-rail PSUs are better for dual GPU systems. I'd say that you can consider yourself safe, but if you experience any system instability, then you have a possible culprit already lined up, just check your 12V rail. Stability of the rail is more important than actual voltage, to a point. So if you're at 11.4V and it doesn't fluctuate, you probably won't experience any hiccups due to power.

Crunchie

Cool. Thanks a lot .

GHoosdum

No problem - good luck!