Hi,
I have a rig which PS is working almost at the top of its power, and I'm afraid it won't be enough on the long term because I read it's meant to loose a bit of power. I think I could get a PS a 20% more powerful to have some margin, would that be enough? Anyone with experience on the matter?
Thanx a lot!
First question is what brand and model is your PSU? Top end units from eVGA, Corsair, Seasonic, etc. can handle higher continuous loads than lesser units.
Second question is how did you measure the power draw, with an at-the-wall measurement or with some other means? An 800 watt PSU will draw more than 800 watts from the wall at its maximum capacity based upon its efficiency. For example, an 90% efficient 800 watt PSU will draw around 890 watts from the wall at its maximum capacity. Conversely, if you have the same 800 watt PSU and are measuring 800 watts at the wall, the PSU is only delivering around 720 watts, so a good PSU (as explained earlier) might be well within its long-term usage limits.
A good website that mainly covers PSUs is
http://www.jonnyguru.com/ They not only review popular PSU's, they have many good articles explaining different aspects of what makes up a good PSU.
In any case, it is still a good idea to have some spare headroom, or margin as you call it, and 20% is a good figure to aim for.