InWin Green Me 750 W Power Supply Review

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We’re back with another InWin PSU, this time it is the top unit from their really new “Green Me” series. I’m going to do my best not to make too many cracks about the series name, we’ll see how that goes.

The Green Me series is aimed at a very tough market indeed, the mid-range wattage and mid-range efficiency market. It sports 80+ Bronze certification and comes in power outputs of 550 W, 650 W and 750 W. Naturally being one of the Benching Team leaders, I just had to request the largest unit. Along with being aimed at a market best described as “tough”, the Green Me is also aimed at being green. As to what that entails exactly I’m not sure, it does come in an interesting reusable and recyclable box at least. I’ll go through what InWin has to say about the Green-ness of it all in the features section.

Features and Specifications

Now that we’re here we’ll go through all the various features listed for this PSU, if anything is worth discussing I’ll comment in italics after the official blurb. Awkwardly the Features and Specification pages at InWin’s product page are not functioning, so I’m going to have to type this up based on what is on the box rather than having access to the entire feature list.

  • Supports the latest Intel ATX12V V2.31& EPS 12V V2.92 Version.
  • Active Power Factor Correction (PF >0.99). Not rare these days, definitely beats passive though.
  • High Efficiency Voltage Transfer Technology, efficiency up to 85%.
  • 5V and 3.3V DC to DC design. This used to be something you only found in top units, I like seeing it here.
  • Smart Thermal Control to balance noise and cooling. See previous.  Not rare these days, but still very nice.
  • 12cm double ball-bearing cooling fan.
  • Patented 4 pin Molex Easy-Swap connectors.
  • Eco-Design of Energy-using Products Directive. I like EuP/Erp, it translates to “Off means off!”
  • Multi-Protection function (OVP, OPP, UVP, SCP, OCP).  I like protections.  Nothing really missing here.
  • Erp lot 6 compliant. Part of the EuP/Erp stuff, I still like it.

As far as being green goes, efficiency is definitely “green”, the ink on the box is green, but that about does it for the features list on the box as far as green goes. Now on the front of the (unbleached cardboard) box it says “100% recyclable packaging”, as well as “DC TO DC DESIGN”, “105c High-Quality Japanese Bulk Capacitor” and “Strict Voltage Regulation (+/- 5%)”. I am totally down with recyclable packaging stuff, recyclable and recycled would be better, but recyclable is great as they’re making a ton of these things. DC to DC we’ll get to in the Dissection Section. 5% voltage regulation is what the ATX spec calls for, I would not call it strict other than that if you go over that you don’t get to say your PSU is ATX compatible.

The specification web page isn’t up yet either (told you this was a brand new design), so I’m going off the box here.

AC Input 100V-240Vac, 50-60Hz, 9.5A
DC Output +12V +12V +12V +12V +5V +3.3V -12V +5VSB
Max. Output 25A 25A 25A 25A 20A 20A 0.3A 3A
Max. Combined Wattage. 744W 120W 18.6W
Total Power 750W

Four rails sounds excellent, especially four juicy rails as listed on the box. Safer than a single-rail design, but beefy enough individual rails that you won’t run into issues with OCP on a rail while trying to power a hungry GPU. Being a DC-DC design I expect to see the 12 V output be quite close to the total unit rating, as everything but 5 Vsb first goes through the 12 V operation.

Interestingly the user’s manual is actually quite informative, enough so that I’m going to put an (almost) full size image of it.

The Owner's Manual

The user's manual

Listing the OCP, OVP, UVP and OPP trip points is a very nice touch. Also note the cable listing, we’ve hit the first hiccup here. Two PCIe power cables/plugs (6+2, though!) is awfully skimpy for a 750 W unit. It’d be generous for a 550 W unit (The Green Me 550 W gets one cable) and perfectly reasonable for a 650 W unit (which does get two), but a 750 W really ought to get four in my opinion. On the plus side you can always use Molex to PCIe adapters. Unfortunately there are only three Molex plugs, which complicates issues a bit. You also get six SATA plugs and a 4+4P ATX/EPS CPU power connector. When you get down to it, I suspect the design was initially for a 650 W and a 550 W and when InWin got the ES units it became apparent that they were awesome enough to extend a bit to 750 W without stressing things, so they did. I have absolutely no issue with that (assuming this thing can cough up 750 W without issue of course!), but more cables would have been nice.

Let’s stop talking about the box and actually look at it, I expect it will be informative and possibly amusing.

Ye Olde Photo Tour

I figure I’ll be boring and start with the box again.

The front. It's green!

The front. It's green!

The rear, still green (and brown).

The rear, still green (and brown)

One end of the box. Still green.

One end of the box

Another flat surface on the box. The bottom maybe?

Another flat surface on the box. The bottom maybe?

Opened the box, inside it's green/brown.

Opened the box, inside it's green/brown

Just brown now. I think I see PSU though!

Just brown now. I think I see PSU though!

Yup, there's the PSU. Not brown, or green.

Yup, there's the PSU. Not brown or green.

I feel that I need to make a statement at this point, so I’m going to. I simply cannot go any further without making at least one amusing statement about the front of the box. “Green Me” is an odd name for a PSU series in the first place. Am I green now? Is it the PSU talking? The PSU looks white, not green! The part that really amuses me is the tagline however: “I care, I do!”. Words cannot express the amusement the front of the box has brought me. HOWEVER! I think that it is absolutely fantastic that InWin is paying attention to their packaging materials and using unbleached paper (the paper bleaching process results in some nasty byproducts that are typically simply flushed into the local water supply, regardless of what country the factory is in) for the cardboard. Using entirely recyclable materials rather than hard or impossible to recycle foam is wonderful as well. Regardless of how green (or not) the PSU itself is, the box/packaging is definitely nicer environmentally speaking than a standard PSU box/packaging setup. I like that a LOT. I would be very happy to see other manufacturers following InWin’s lead here, because when you get down to it, I care, I do!

I figure by this point you’re ready to stop reading and start looking at pictures, so I’ll oblige and show you some pictures of the PSU.

The PSU accessories.

The PSU accessories

A closer view of the fan side of things.

A closer view of the fan side of things

The label.

The label

The white crackle finish. It's nice.

The white crackle finish. It's nice.

Back of the unit

You want angles? We've got angles.

You want angles? We've got angles.

Really there isn't that much to see.

Really there isn't that much to see

This side has a label at least.

This side has a label at least

Usually these are inside the case.

Usually these are inside the case

I didn’t notice the cable tie in the last picture until I was trying to disassemble the unit, it isn’t as obvious as the picture makes it look. Usually if a PSU has a cable tie tasked with this job it is entirely inside and uses a loop of metal. That costs more however, and it looks like InWin was working hard to keep the price down. I like low prices and don’t mind a cable tie like that, so it’s fine with me.

Other than that, the Green Me is a pretty simple crackle white finished box, even the label is black and white. If you have a white case it will fit in wonderfully, if you don’t have a white case you can take advantage of the fact that if you aim a colored LED at it you’ll have excellent results. If you’re going for a stealth install and were hoping for a black PSU, it might be time for spray paint. Personally, I’ve done the LED bit and it really does look quite nice, with a blue LED it looks like the entire PSU is glowing. Fantastic!

Having counted cables I can confirm that there really are only two PCIe power plugs and three Molex power plugs, which is a bit on the skimpy end, in my opinion.

Load Testing

A decent load test of a PSU requires a decent load. Contrary to what some may believe, that means you need a known load that can fully stress the PSU. Computer hardware does not cut it. Worse if the PSU fails during testing it might take out the computer hardware anyway. Commercial load testers cost a lot of money. I do not have a lot of money, so I built my own with juicy power resistors and a Toyota cylinder head. It works great. I’ll be using it to load this thing down fairly severely and will check voltages and ripple (more on that later) at various points. The down side to my tester is that the loads it can put on PSUs are fairly coarse, they go in increments of 48 W for 12 V, 50 W for 5 V and 22 W for 3.3V. Those wattages assume the PSU is putting out exactly the official rail voltage, a PSU putting out 12.24 V rather than 12 V will be at 49.9 W per step rather than 48 W. I file that under the “tough beans” category as I figure if a percent or two of load makes that much of a difference the PSU manufacturer should have hit the voltage regulation more squarely.

The ATX spec says that voltage regulation must be within 5% of the rail’s official designation, regardless of load. It doesn’t actually mention that the PSU shouldn’t explode, though I expect they figured it was implied. Exploding is a failure in my book regardless.

Without further ado, we have the load test results!

Rail Wattages (total) 12 V Rail 5 V Rail 3.3 V Rail
0/0/0w (0w) 12.28 5.14 3.38
96/0/0w (96w) 12.27 5.13 3.38
240/50/22w (312w) 12.24 5.04 3.34
432/100/22w (555w) 12.18 5.01 3.33
624/100/22w (746w) 12.12 5.00 3.32
720/0/0w (720w) 12.10 5.10 3.35

Not bad at all!  Well within spec. 12 V has 1.4% regulation, 5 V 2.8% regulation and 3.3 V 1.5% regulation. Really quite solid, if not as good as the InWin Glacier 900 W’s regulation (few units are, really). 5 V fades a bit, but if you look back at the spec 5 V is putting out 100% of its rated power, something that will never happen in real life and is really rather rude when you get down to it.

Starting a few minutes into test #3 the fan woke up a bit and in test #4 it ramped up to where it was making a decent amount of airflow noise. Nothing offensive though.

All together I’m impressed, if the InWin Green Me 750 W can do that well through the ripple testing we have a winner on our hands here!

Ripple Testing

Ripple is fluctuation of the PSU’s output voltage caused by a variety of factors. It is pretty much impossible to have zero ripple in a SMPS computer power supply because of how a SMPS works, so the question is how much ripple is there? In the regulation testing phase we found out how the PSU does at keeping the average voltage at a set level, now we’re going to see what that voltage is doing on really short time frames. The ATX spec says that the 12 V rail cannot have more than 120 mV peak to peak ripple, the 5 V and 3.3 V rails need to stay under 50 mV.

If that isn’t complicated enough for you, there are three forms of ripple to keep track of as well. Long-term ripple from the PSU’s controller adjusting the output voltage and over/undershooting, correcting, overshooting, etc. Medium-term ripple from the voltage controller charging and discharging the inductor(s) and capacitor(s) that make up the VRM, and very short-term ripple caused by the switching itself. The first and second forms are the most important, if they are out of spec it can cause instability at best or damage in extreme situations. The very short-term (I call it transient ripple) flavor is less crucial, excessive amounts can still cause issues though it takes more of it to do so. The ATX spec does not differentiate, as far as the spec goes 121 mV of transient ripple is just as much of a failure as 121 mV of medium or long term ripple.

I tested the ripple at very low load (the PSU is not rated for zero load operation, I put 48 W on the 12 V rail to stabilize it) and full unit load. On units that are not DC-DC regulation I generally do a heavy 12 V crossload as well, on DC-DC units such as this one all the power goes through the 12 V regulator first anyway.

For the ripple shots, the scope settings used to find the worst ripple (and keep it on-screen) varied widely, so be sure to read the captions.  We’ll do 12 V first, then 5 V, then 3.3 V. For some reason my scope was not at all interested in triggering cleanly for the 5 V and 3.3 V low load shots.

12 V low load ripple, ~29 mV (scope: 10 uS / 10 mV)

12 V low load ripple, ~29 mV (scope: 10 µs / 10 mV)

12 V full unit load ripple, ~75 mV (scope: 10 ms / 20 mV)

12 V full unit load ripple, ~75 mV (scope: 10 ms / 20 mV)

12 V crossload ripple, ~68 mV (scope: 10 µs / 20 mV)

12 V crossload ripple, ~68 mV (scope: 10 µs / 20 mV)

Nothing really to report here, 75 mV isn’t breathtakingly low, but it’s well inside the 120 mV spec. This unit passes 12 V ripple testing easily.

5 V low load ripple, ~28 mV (scope: 1 µs / 10 mV)

5 V low load ripple, ~28 mV (scope: 1 µs / 10 mV)

5 V low load ripple, ~53 mV (scope: 5 µs / 10 mV)

5 V full unit load ripple, ~53 mV (scope: 5 µs / 10 mV)

5 V (12 V crossloaded) ripple, ~44 mV (scope: 10 µs / 10 mV)

5 V (12 V crossloaded) ripple, ~44 mV (scope: 10 µs / 10 mV)

5 V just barely fails ripple spec with the unit fully loaded and the 5 V rail loaded to 100% of its rating. How barely? Barely like it is out of spec by 3 mV or so for something less than a millionth of a second. I have to score it as the ATX spec is rather specific on that front, but I would be truly shocked if it caused any issues. You’ll need to click the picture and squint a bit to see the transient spike that goes over 50 mV.

3.3 V low load ripple, ~21 mV (scope: 1 µs / 10 mV)

3.3 V low load ripple, ~21 mV (scope: 1 µs / 10 mV)

3.3 V full unit load ripple, ~37 mV (scope: 5 µs / 10 mV)

3.3 V full unit load ripple, ~37 mV (scope: 5 µs / 10 mV)

3.3 V (12 V crossload) ripple, ~44 mV (scope: 10 µs / 10 mV)

3.3 V (12 V crossload) ripple, ~44 mV (scope: 10 µs / 10 mV)

The 3.3 V rail has some very interesting shapes to it, but stays within spec. As with the 12 V the ripple results aren’t anything to write home about, but they do pass.

For the last test I monitored the 12 V rail regulation and ripple at 100% unit load and placed the PSU in Bobnova’s Box of Doomish Heat. I kept it in there until it had an intake air temperature of 35 °C and held it at 35 °C intake for ten minutes. During that time the ripple was better, regulation was still good and exhaust temperatures were ~46 °C. The fan ramped up pretty decently, but didn’t make any nasty or annoying sounds.

If you’re wondering what Bobnova’s Box of Doomish Heat is, I’ll tell you. If you aren’t wondering, I’ll still tell you. It is a recycled recyclable unbleached cardboard box with slots cut for the input and output wires, along with two thermocouple probes. I placed it over the PSU so the PSU sucked its own hot air right back in the intake. Temperatures are modulated manually by lifting or lowering the edge of the box near the PSU’s exhaust vent. Crude, but effective.


Disclaimer: Power supplies can have dangerous voltages inside them even after being unplugged, DO NOT OPEN POWER SUPPLIES. It’s just not a good idea, and doing so could very well kill you. Don’t try this at home. Don’t try this at work. Just don’t do it. 

First, overview shots!

An overview.

An overview

Good soldering.

Good soldering

Opening the PSU we see a platform I’m not familiar with (The UL number traces to “BRITE PLUS ELECTRONICS (SUZHOU) CO LTD“, I’m not familiar with them either). Popping the PCB out reveals soldering I would describe as “good”, though not excellent. There are a few areas where SMD bits are hand soldered and a few other bits where a soldering iron touched down for unknown reasons. Nothing I would consider an issue though, and other than those spots the soldering is quite good.

Next, we’ll follow the power through the unit as it heads in from the wall, through the unit, and out to the computer. Ignoring the fact that the “power” doesn’t, nor do any electrons, or any other single thing. Electrical theory is weird.

In any case our tour starts with the receptacle, which has a pair of Y capacitors soldered to it as a first state of transient filter. There is a ferrite bead on the power leads that go to the main PCB too. Following that comes a fuse, a TVS diode for surge protection, two X capacitors and two inductors. Note the perfect placement of the TVS diode.

The receptacle and power switch.

The receptacle and power switch

Most of the transient filter.

Most of the transient filter

On the far side of the heatsink, we find two GBU806 (8 A, 600 V) rectifiers, an X capacitor on their output leads, and two more Y capacitors that are wired to the AC input.

Last the transient filter Y caps, rectifiers, and output X cap.

Last the transient filter Y caps, rectifiers and output X cap

The rectifiers.

The rectifiers

The APFC switches are a pair of 21N50C3 (21 A @ 25 °C, 13 A @ 100 °C, 560 V) MOSFETs, the boost diode is a nice standard BYC10 (10 A, 600 V) unit and the bulk storage cap is indeed Japanese and rated at 105 °C. The brains of the operation are on their own little PCB, which not only houses a CM6802 APFC controller but has Green Me printed right on it.

One of the two APFC switches.

One of the two APFC switches

The boost diode.

The boost diode

Panasonic is quite Japanese. 450 V is nice to see.

Panasonic is quite Japanese. 450 V is nice to see.

The brains of the APFC unit.

The brains of the APFC unit

Moving right along the main switches are a pair of 21N50C3 (21 A @ 25 °C, 13 A @ 100 °C, 560v) MOSFETs, the 12 V output is rectified by four 40L60PT (40 A, 60 V) schottky diodes. 5 V and 3.3 V are supplied via DC-DC regulation boards, each with two M3016D and two M3004D MOSFETs, neither of which can I find datasheets for. The switching brain is a TNY278PN, while a WT7579 is on protection duty. Output filter caps are Teapo and Samxon 105 °C rated units.

Switching brain.

Switching brain

Protection brain.

Protection brain

One of the two main switches.

One of the two main switches

12 V rectifier, one of four.

12 V rectifier, one of four

The output filter, most of it anyway.

The output filter, most of it anyway

There really are four rails.

There really are four rails

5 V and 3.3 V DC-DC boards.

5 V and 3.3 V DC-DC boards

The other side.

The other side

InWin was fairly liberal with the white silicone caulk, while it looks messy it does a good job protecting against shipping damage as well as reducing inductor whine at high loads. I’m a big fan of it when I’m not scraping it off things to read the part numbers.

Last, the fan hub:

Adda again, probably the most common PSU fan.

ADDA again, probably the most common PSU fan

Final Thoughts and Conclusion

I’m forced to admit that I started this review by laughing. While I stand by that laughter, I also have to say that this is really a rather good PSU. It isn’t without issues, though little is in the existence we all inhabit here on Earth. The 5 V ripple having transients that just barely violating spec is sad from the standpoint that I have to mention it, but I don’t see it causing any issues. The other rails did just fine in ripple testing, not spectacular but not bad either. Voltage regulation was good for a unit in this price range, it can’t touch the InWin Glacier 900 W unit’s <1%, but the numbers from this unit are nothing to sneeze at. The shortage of PCIe power cables could be an issue, be prepared to bust out the Molex-PCIe adapters if you’re using multiple GPUs. A couple more Molex plugs would be nice as well, especially if you have to use them to power GPUs.

The price is quite good at $99, I can only find one unit in this wattage/efficiency range for less and it isn’t much less. Most comparable unit are the same price of $5-$10 more expensive. Four rails with juicy OCP trip points is ideal from a safety standpoint. The fan does a good job of staying quiet when possible, by the time you draw enough power to spin the fan up the odds are excellent that whatever is drawing the power will drown out the PSU fan noise. White color shows off LEDs in your case really well and is fairly rare. I really am a fan of the “green” packaging, I hope that it catches on and other companies follow suit.

All told there are plenty of pros:

  • Good price.
  • Good voltage regulation.
  • Good build quality.
  • Recyclable environmentally friendly packaging.
  • One of a very few worthwhile white units out there.
  • Four 12 V rails, excellent!

It’s not all sunshine and roses however, as usual some cons have snuck in as well:

  • 5 V rail (barely) violates ripple specs with transients.
  • Two PCIe cables is skimpy for a 750 W unit.
  • Could do with a couple more Molex plugs, too.

All told, I definitely approve of the InWin Green Me 750 W power supply, it has a nice juicy pro list and a short con list as well as amusing packaging. How could I not approve it? It cares, it does! Seriously though, if you don’t need more than two PCIe cables this is a good unit with a good message.

Click the Approved picture for an explanation of what it means

 – Bobnova

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  1. I like the white too, it looks a bit out of place in a black case with no LEDs, but if you aim an LED at it the whole PSU practically glows. It's pretty glorious really.
    I rather like the actual look of the unit. The black and white stickers suit it, other manufacturers could learn a thing or two from this regarding simple yet stylish packaging.... Mind you, I love the shiny gold label on the other unit that was reviewed recently..... So very sexy..... I'm sure it'd be terrible for fingerprints though whereas with white you'd never even see them