Electronic techs & Electricians please come in.

[NoShangriLa]

I have an older MPT-3012 with sticker rated @ 300W max.

Manufacture rated input @ 115V ~ 6A
Manufacture rated output @ 300 Watt max.

According to MACRON spec sheet the MPT-3012 VA output total is 607.85W.

And my calculation for it is:

Input = 115V * 6A = 690W
Output = my understanding of AC/DC converter is up to 90% efficent and modern converter is at least 80% efficient, therefore PS output should be 690W * .8~.9 = 552~621W (actual V out of my wall socket is 118V).

I hope that I'm correct with the calculation, because my calculation indicated that the PS should be rated @ 439.88~455.89W. Which is well over the 357.8W peak that I need for my new system.

 

[HOOfan 1]

Efficiency is based on the topology of the power supply. If it is an older power supply and was farily cheap, then I doubt very seriously it is 80% efficient. Also seeing a picture of it on the web...and seeing that it doesn't have APFC...I highly doubt it is 80% efficient Besides that, efficiency is not the only factor determining a PSU's output...that would include how much current the switching transistors and rectifiers can handle as well. If the PSU is rated at 300W max, then I would say it is a 300W unit.

 

[Zepper]

I've not heard Macron being touted as a top brand or anywhere close. I recall lots of failures with those which were included in some of the C-M Cavalier HTPC style cases. PSUs lacking the 80 Plus sticker are only likely to hit 80 percent efficient over a small portion of the output range. Look at some of the reviews on JonnyGuru's web site to find out real world. The fuse (6A max indicated) is not an indicator of actual AC power input (which varies with the load) - the fuse is protection from extreme situations, not routine operation. Get yourself a Kill-A-Watt meter and you can find out for yourself. You are looking at efficiency just backwards - to test it, you put a known dummy load on the PSU (so you know just how many watts are being used) then measure how many watts are being drawn from the wall. Watts OUT divided by Watts IN gives you the efficiency value at that load. I know my system (just the CPU box) draws less than 250 Watts at the wall at most times. Some PSUs are capable of safely delivering as much as 10% over their ratings, but most aren't - particularly third and 4th tier brands. A lot of those can't even make their rated power w/o blowing up.

. Unless you don't care about your system, get a good brand PSU of the rating you need. The old Antec Earthwatts units made by Seasonic are examples of reasonably priced (when you can find them on sale or new pulls on fleabay) PSUs which can actually meet their ratings. IDK about the new Delta made Earthwatts units yet.

In AC, Volts * Amps only equals Watts when the Power Factor is at 1 (meaning the load looks like a resistor to the PSU). Otherwise it's just called Volt-Amps. PSUs with active Power Factor Correction (aPFC) try to keep their PFs as close to 1 as possible by compensating for the reactivity of the load. The Seasonic made Earthwatts units keep their PFs at 0.9 or better, which is typical of a good aPFC circuit. There are plenty of other PSUs out there (some OCZ, Corsair, et al.) that are made by Seasonic and almost all of them are very good to excellent and generally cost less than Seasonic branded ones.

.bh.

 

[NoShangriLa]

My bad PSU efficency aren't anything like AC/DC converters that I use ou in the industry.

Switched-mode power supply typical efficiency.

 

[Zap]

Originally posted by: Zepper
The old Antec Earthwatts units made by Seasonic are examples of reasonably priced (when you can find them on sale or new pulls on fleabay) PSUs which can actually meet their ratings. IDK about the new Delta made Earthwatts units yet.

The Delta EarthWatts should be just as good. Delta made the Antec Signature series which many consider to be excellent. Also, the very first Delta made EarthWatts was reviewed at jonnyGURU.com and got a 9/10.