Gigabyte, mostly known for its motherboards and graphics cards, is participating in one of our power supply round-ups for the first time. Its Greenmax Plus 450W is a good fit for this budget-oriented comparison. Currently, only the company's 550 and 650 W Greenmax models are available in the U.S., but based on their pricing, we expect the 450 W version to show up in the $50 to $60 range.
Since this is not a high-end PSU, we aren't surprised by its fairly standard features. Its build quality seems OK, but not outstanding. The cables are non-modular and fully sleeved though, which is nice. The cable lengths and the number of connectors are average. There are but three Molex connectors and only one 6+2-pin auxiliary PCI Express connector. So, this power supply isn't really suitable for dual graphics cards, or even a gaming rig with one high-performance card (though that should have been pretty obvious in light of its maximum output). The 450 W PSU sports two +12 V output rails, each of which can deliver up to 25 A for a combined maximum of 32 A. No screws or Velcro bands are included.
| Gigabyte Greenmax Plus 450W | ||||||||
|---|---|---|---|---|---|---|---|---|
| AC Input | 100-240 V, 50-60 Hz | |||||||
| DC Output | +3.3 V | +5 V | +12 V (#1) | +12 V (#2) | +12 V (#3) | +12 V (#4) | -12 V | +5 Vsb |
| 20 A | 21 A | 25 A | 25 A | n/a | n/a | 0.5 A | 3.0 A | |
| Individual Output | 32 A | 6 W | 15 W | |||||
| Rail Utilization | Sys | Sys | CPU & VGA | |||||
| Combined Output | 120 W | 378 W | ||||||
| Total Continuous Output | 450 W | |||||||
| Peak Output | 550 W | |||||||
- At $45 And Up, We Reach For Power Supply Gold
- Cooler Master Silent Pro M2 520W
- Cooler Master Silent Pro M2 520W: Measurements
- Corsair CX500
- Corsair CX500: Measurements
- Gigabyte Greenmax Plus 450W
- Gigabyte Greenmax Plus 450W: Measurements
- Seasonic SSR-360GP
- Seasonic SSR-360GP: Measurements
- Test Configuration, Hold-Up Time, And Inrush Current
- Efficiency According To The 80 PLUS Spec, Standby Power, And Sound Level
- Part 2: Which One Of These PSUs Is Right For You?
- Model Comparison Table






Perhaps you should measure the inductance of your bulbs, rather than just stating they are purely resistive.
Thanks guys, nice article!
In the CX500. I think Samxon caps count as cost cutting.
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.
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.
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?
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.
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.
Inductors react to change in current and attempt to counter it. On a constant voltage with a constant resistance, current is also constant.
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.
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.
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
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.
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.
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).