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Review: In Win GreenMe 750W PSU

by Tarinder Sandhu on 19 July 2012, 16:29 3.5

Tags: In Win

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Running the numbers

Our testing procedures can be found at this link.

Efficiency

Load 10pc 25pc 50pc 75pc 100pc
Efficiency 78.4pc 85.2pc 88.1pc 87.3pc 86.0pc

Efficiency is higher, read better, than that mandated by 80 PLUS' Bronze certification when evaluated from a 230V source. The supply pulls 425W from the mains to deliver a 50 per cent load of 375W to the Chroma test equipment, losing 50W in resistance and heat. Ramp it all the way up to a desired 750W - constituted by 12V load, in the main - and the supply needs 872W from the mains. Providing some context, a Platinum-rated PSU of the same capacity would need no more than 824W for the same full-load draw. Overall, considered with respect to its class, efficiency is decent for a £65 supply.

Regulation

In terms of regulation, we're looking at just how well the supply is able to hold to the various lines. The ATX spec. has a +/- 5 per cent leeway on all but the -12V line.

Line/Load 3.3V 5V 12V
10 per cent +1.5pc +0.6pc +1.4pc
50 per cent -0.3pc -0.8pc

+0.6pc

100 per cent -2.2pc -1.9pc -1.3pc

Genuinely premium supplies can hit each of the preset loads by wavering less than one per cent away from ideal voltage regulation. The GreenMe 750W isn't as good, understandably so given its price, but remains well within the ATX specification.

Regulation - cross-load

How about providing uneven loads that stress particular voltage rails? In the first attempt, we've put 60A on the 12V rails, and 1A on the 3.3V and 5V rails. This can actually be somewhat typical for a system heavy on graphics and CPU power. In the second, we've turned the tables and gone for 12A on both the 3.3V and 5V rails - highly unlikely in a real-world environment - and just 2A on the 12V - even more unlikely!

Line/Load 3.3V 5V 12V
Cross-load 12V focus +1.3pc +1.1pc -1.0pc
Cross-load 3.3V/5V focus -1.9pc -2.2pc +1.8pc

Hammering one part of the PSU power delivery while using just a small portion of the other can throw cheaper supplies of out kilter. Pushing and pulling the voltage and lines does cause the regulation to suffer a touch. But again, it's nothing that we'd worry about.

Ripple

Line/Load (mv - p-p max) 3.3V 5V 12V
10 per cent 10mV 10mV 15mV
50 per cent 15mV 10mV 45mV
100 per cent 20mV 18mV 80mV

The ATX v2.2 spec states that the maximum permissible ripple is 120mV for the 12V line and 50mV for others.

PSUs convert AC power into DC, but doing so requires the AC waveform to be suppressed. What we're really testing here is the quality of the supply's rectifier and any smoothing capacitors in getting rid of this unwanted up-and-down ripple. The standout figures are for 50 and 100 per cent load on the 12V line. The numbers are perfectly within ATX specification but cannot get close to the 30-50mV standard set by a number of Gold and Platinum supplies. Considering it properly, with respect to price vs. capacity, the In Win GreenMe 750W meets and exceeds common standards though its 12V ripple does start to become noticeable at full load.

Temps and noise

Temperatures Intake Exhaust
10 per cent 27°C 34°C
50 per cent 32°C 37°C
100 per cent 37°C 45°C

High efficiency ratings tend to go hand-in-hand with low-ish temps; there's not a great deal of heat being created by the PSU. The supply's fan is active at all times, unlike some of the competition, but it's not noticeable at loads below 50 per cent. Increase the load to around 75 per cent and the fan spins up to around 1,250RPM. We'd term the noise just above average for a supply of this class.