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Gigabyte Greenmax Plus 450W: Measurements

Part 2: Four Cheap 80 PLUS Bronze Power Supplies, Reviewed
By

Efficiency According to the 80 PLUS Spec

Efficiency by Load

Of course, lab results matter more than bundled goodies. So, let’s start with our two pet peeves: ripple and noise. Like all of the power supplies in our round-up, we observe brief spikes on the output rails. They're most pronounced on the 5 and 3.3 V rails. While even the 12 V rails exhibit spikes, they are within the ATX specification's limits. When we disregard the peaks, the oscilloscope's waveforms look a lot nicer.

The Greenmax Plus 450W's efficiency is almost on a par with Cooler Master and Corsair, which is to say it's good. This 450 W power supply stands out from the crowd in two ways. First, its inrush current is quite high at 230 V (62 A). On the other hand, its hold-up time is approximately 25 ms, or almost twice as good as the Silent Pro M2's hold-up time. However, the Greenmax Plus is outclassed by other PSUs when it comes to our acoustic measurements. We observed up to 35.5 dB(A), which is quite audible in a quiet room.

A Close Look at the PCB

The Greenmax Plus 450W's yellow PCB is somewhat smaller than the chassis can fit, which means the layout is necessarily compact. The cooling fins are pretty diminutive compared to Cooler Master's, for example. But we noticed that Gigabyte still uses quality components; there's no cost-cutting we can readily identify. The main capacitor on the primary side is made by Japan-based Nippon Chemi-Con, while the other capacitors are made by Samxon (we already encountered this brand inside Corsair's CX500). While the input filter is not split into two parts, we found all necessary components. We also found the soldering quality to be OK.

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Top Comments
  • 25 Hide
    Deemo13 , August 28, 2013 10:13 PM
    You guys aught to make a power supply hierarchy chart.
Other Comments
  • 25 Hide
    Deemo13 , August 28, 2013 10:13 PM
    You guys aught to make a power supply hierarchy chart.
  • 1 Hide
    pepsimtl , August 28, 2013 10:50 PM
    Please, if you could say , if the power supply is compatible with Haswell .I think this is very important .
  • -2 Hide
    benedict78 , August 28, 2013 11:49 PM
    I second that request. Does ANY of those PSUs support the new Haswell C7 state?
  • 4 Hide
    ojas , August 29, 2013 2:09 AM
    There's also a CX500M...
  • 0 Hide
    jeffunit , August 29, 2013 2:13 AM
    I am not sure why you think that a 40w bulb is purely resistive. Almost all bulb filaments are coiled, which makes them inductive. For example, http://www.donsbulbs.com/cgi-bin/r/b.pl/h4652|12.8v|40w|60w~usa.html shows a 12v 40w bulb filament, which is coiled.

    Perhaps you should measure the inductance of your bulbs, rather than just stating they are purely resistive.
  • 0 Hide
    vertexx , August 29, 2013 3:09 AM
    A couple different PSUs for different applications. I use the Corsair CX 430 & 500 for budget gaming builds, and just this week I ordered the Seasonic for the first time for a home server build. Nice to see those choices validated.

    Thanks guys, nice article!
  • 4 Hide
    Someone Somewhere , August 29, 2013 3:53 AM
    Quote:
    In spite of its low price, no important components fall victim to cost cutting.


    In the CX500. I think Samxon caps count as cost cutting.
  • -9 Hide
    flong777 , August 29, 2013 3:54 AM
    I have recommended the CX500 many times to budget builders and now I feel better about it. It is the clear winner. Funny TH says it is loud but it was nearly identical to the CM 520 on their chart in DB noise.

    On sale you can pick up the CX500 for $40 which is about as cheap as you will ever find any PSU. If you compare how well that Corsair backs its products, there really is no comparison - Corsair is the only choice.

    As far as the Seasonic 360, why on earth would you buy a 360W PSU? I just don't see the point. While I can justify a 500W PSU to a budget builder, I really cannot comprehend recommending a 360W PSU to anyone. I feel cautious with a low wattage 500W PSU. All of these PSUs will run hot and loud if they are stressed and so moving up to a 650W or even an 850W PSU really is not that more expensive.

    I got the gold rated 850W Corsair HX 850 for $144.00 on sale. I can not even begin to describe how excellent this PSU is. It runs as something around 92% efficiency under load and I have never hear the fan even come on (it may be that low fan is inaudible). It comes with a 7-year warranty and is modular.

    If you are not strapped with a low budget, moving up is the only way to go. If you are, the CX 500 is a good choice.

  • 2 Hide
    vertexx , August 29, 2013 4:32 AM
    Quote:
    As far as the Seasonic 360, why on earth would you buy a 360W PSU? I just don't see the point. While I can justify a 500W PSU to a budget builder, I really cannot comprehend recommending a 360W PSU to anyone.

    I just ordered the Seasonic for a home server build. The higher efficiency is a plus since it will be running 24x7. Plus, the system really doesn't need the extra wattage.

    PSUs run more efficiently under load. IMO, the trend has been to overkill on the PSU when it's not really needed. In reality, when you actually add up the max loads of all components a 350-450W PSU is more than enough to run most single GPU gaming builds.
  • 1 Hide
    vertexx , August 29, 2013 4:38 AM
    Quote:
    I am not sure why you think that a 40w bulb is purely resistive. Almost all bulb filaments are coiled, which makes them inductive. For example, http://www.donsbulbs.com/cgi-bin/r/b.pl/h4652|12.8v|40w|60w~usa.html shows a 12v 40w bulb filament, which is coiled.

    Perhaps you should measure the inductance of your bulbs, rather than just stating they are purely resistive.

    It's been a while since I've been involved in DC power calculations, but these bulbs are DC bulbs. At DC steady state, what role does inductance play?
  • 4 Hide
    JimmiG , August 29, 2013 4:40 AM
    Quote:
    Please, if you could say , if the power supply is compatible with Haswell .I think this is very important .


    All PSUs are compatible with Haswell. It's only the C6/C7 idle states that *may* cause problems.

    Any PSU that uses DC to DC for the non-primary rails will support these idle states. Most other PSUs will be just fine as well. Remember that even if the CPU is drawing almost no power, you usually have some fan, hard drive etc. that's active on the 12V rail. I've never had any problems with my 5 years old Corsair VX 450W and my 4770K with C6/C7 enabled.

    Even if you end up having to disable C6/C7 sleep, it will only increase power consumption by 3W at idle. This may make a difference with laptops, but it's hardly an issue with desktops.

    Quote:
    PSUs run more efficiently under load. IMO, the trend has been to overkill on the PSU when it's not really needed. In reality, when you actually add up the max loads of all components a 350-450W PSU is more than enough to run most single GPU gaming builds.


    True. PSUs only reach peak efficiency under a certain load. With an overpowered PSU, you may never load it enough for it to reach peak efficiency. A smaller PSU might end up being more efficient.

    My 4770K overclocked to 4.5 GHz and a factory overclocked GTX 670 reaches 405W at the wall when stress-testing the GPU and CPU simultaneously. In games, it's at 250 - 310W depending on the game.
  • 0 Hide
    Someone Somewhere , August 29, 2013 4:42 AM
    None at all...

    Inductors react to change in current and attempt to counter it. On a constant voltage with a constant resistance, current is also constant.
  • 0 Hide
    vertexx , August 29, 2013 4:54 AM
    Looking at those voltage spikes, I'm wondering if the DC bulbs could be the cause of that.

    A couple of other guys have commented on the inductance of the light bulbs. While I don't think inductance has anything to do with DC loading at steady state, it certainly can play a role with fluctuations in DC loading (i.e. startup, shutdown, and fluctuations).

    Those spikes occur at relative minimums and maximum voltages within the minor fluctuations of each PSU. If I remember correctly, that would indicate points where current is changing. Since inductance resists changes in current flow, that could cause a spike in voltage.

    Interested in your thoughts on that.
  • -1 Hide
    Someone Somewhere , August 29, 2013 5:01 AM
    Retest with a lot of NiChrome wire in a bucket?
  • 0 Hide
    InvalidError , August 29, 2013 5:18 AM
    Quote:
    Looking at those voltage spikes, I'm wondering if the DC bulbs could be the cause of that.

    Unless lightbulbs which are passive devices have something in them that can generate glitch energy at over 10MHz, no.

    The spikes are caused by impulse noise that occurs during the brief cross-conduction when switching elements inside the PSU toggle from forward rectifiers to free-wheeling rectifiers. For the few nanoseconds it takes for one device to turn on and the other to turn off, both will be conducting at the same time and this will momentarily short out the transformer's output. Although this cross-conduction is generally undesirable, some of it is necessary since without it, EMF from output inductors could destroy synchronous rectifiers.

    In a real-world application, the PSU would have over 10 000uF worth of extra capacitance from the motherboard which should considerably reduce if not eliminate most of the (very-)high-frequency noise from the PSU visible from the motherboard's point of view.
  • 0 Hide
    vertexx , August 29, 2013 5:25 AM
    Quote:

    Unless lightbulbs which are passive devices have something in them that can generate glitch energy at over 10MHz, no.

    I'm not saying this is definitely the reason, but a passive inductive load absolutely can cause a voltage spike with a fluctuation in current. Although your answer sounds a lot more smarter than mine.

    But the theory is sound - more detailed explanation here:
    http://www.daycounter.com/Articles/Inductive-Voltage-Spike.phtml
  • 5 Hide
    Onus , August 29, 2013 5:30 AM
    Over at HardwareSecrets, there's a guy named c.hegge who is an Australian PSU reviewer. He has documented how bad the Samxon "GF" capacitors are. They don't like heat, and tend to fail. He has recapped Corsair "CX" PSUs with capacitor problems. This is also described on the badcaps.org forums. The Corsair CX reviews well, and looks great when new, but I won't buy or recommend them, especially in gaming PCs that tend to run warm.
    Of this batch of PSUs, I'd take the Seasonic every time. As Vertexx points out, it offers sufficient wattage for most PCs with a single graphics card using just one PCIe power connector.
  • 0 Hide
    InvalidError , August 29, 2013 6:01 AM
    Quote:
    I'm not saying this is definitely the reason, but a passive inductive load absolutely can cause a voltage spike with a fluctuation in current.

    Not if the voltage spike is too short for the inductor's current to change by a significant amount.

    Also, a passive load being excited at 200-500kHz by the PSU's ripple voltage would not mysteriously generate noise at over 10MHz no matter how capacitive or inductive it might be unless you make/break contact but then it wouldn't be quite a passive load anymore since it is being actively switched on/off.

    Additionally, the back-EMF spike only applies when you are attempting to disconnect an inductive load before its current drops to zero. Here, the light bulbs remain connected to the PSU so there would be no make/break spikes from whatever inductance those bulbs might have as described in your link.
  • 0 Hide
    Maxx_Power , August 29, 2013 7:28 AM
    For those who worry about the inductance of the light bulb, remember that the inductance is proportional to the amount of electrons in the conductor, and therefore, for a length of wire, is proportional to the length and diameter of the wire, as well as the conductance of the wire.

    To put it in perspective, the wire in a coiled incandescent light bulb (there are non-coiled ones) is very very thin (sub-milimeter), and about 60 cm long (2 feet). Therefore, the max inductance of the wire is about the same as a single strand of a stranded wire in the PSU wiring or the bench-test box wiring, and thus, much much less than the total inductance of the system, just due to wiring alone. In this way, Toms correctly considered the inductance of the light bulbs to be negligible, when compared to the principal resistance of the light bulb (the resistance of the bulb-wire is high, particularly when it is heated up).
  • 1 Hide
    rolli59 , August 29, 2013 7:36 AM
    Great to see PSU reviews again at Toms. After these two I am glad I vent with the Antec HCG400 when I needed a spare last year.
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