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Additional technical assistance: Peter McFarland and Jeremy Price.
Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. Due to public requests we have changed our temperature settings recently – previously we rated with ambient temperatures at 25C, we have increased ambient temperatures by 10c (to 35c) in our environment to greater reflect warmer internal chassis conditions.
We use combinations of the following hardware:
• SunMoon SM-268
• CSI3710A Programmable DC load (+3.3V and +5V outputs)
• CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa)
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA
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DC Output Load Regulation
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Combined DC Load |
+3.3V
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+5V
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+12V
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+5VSB
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||||
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A
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V
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A
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V
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A
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V
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A
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V
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75W
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1.02
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3.39
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1.46
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5.05
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4.89
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12.21
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0.50
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5.03
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150W
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2.44
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3.36
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3.16
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5.03
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9.71
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12.17
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1.00
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5.02
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250W
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3.66
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3.33
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5.18
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5.01
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16.54
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12.15
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1.50
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5.01
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| 350W |
4.95
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3.32
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7.06
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4.99
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23.53
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12.12
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2.00
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5.00 |
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455W
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6.77
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3.28
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9.18
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4.98
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32.78
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12.09
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2.50
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5.00
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Load regulation is excellent and all output maintain close to reference results.
| Seasonic X-Series 460W Fanless | Maximum Load |
| 492.6 |
We managed to push the supply to 492.6 watts before it would shut down safely.
Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.
| Cross Load Testing | +3.3V | +5V | +12V | -12V | +5VSB | |||||
| A | V | A | V | A | V | A | V | A | V | |
| 386W | 2.0 | 3.38 | 2.0 | 5.05 | 30.0 | 12.08 | 0.2 | -12.12 | 0.50 | 5.02 |
| 171W | 18.0 | 3.30 | 12.0 | 4.99 | 4.0 | 12.19 | 0.2 | -12.07 | 0.50 | 5.00 |
Our first test placed a heavy load (30a) on the +12 V output with a light load on the remaining voltages. The supply delivered excellent results across out of the output range.
We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum.
ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.
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ATX12V Ver 2.2 Noise/Ripple Tolerance
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Output
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Ripple (mV p-p)
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+3.3V
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50
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+5V
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50
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+12V1
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120
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+12V2
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120
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-12V
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120
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+5VSB
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50
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Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.
| AC Ripple (mV p-p) | ||||
| DC Load | +3.3V | +5V | +12V | 5VSB |
| 75W | 5 | 5 | 10 | 5 |
| 150W | 10 | 5 | 15 | 10 |
| 250W | 10 | 5 | 15 | 15 |
| 350W | 10 | 10 | 20 | 15 |
| 455W | 15 | 10 | 25 | 15 |
An incredible set of results and actually some of the best we have seen to date. Only 25mV at full load from the +12v. The other output are just as impressive, peaking at 10mV/15mV from the +3.3V and +5V respectively.
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Efficiency (%)
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75W
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87.34
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150W
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88.53
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250W
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92.15
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350W
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91.48
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455W
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90.79
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Again, very good results from the Silver Power supply, peaking just over 92 % efficiency at 50 percent load.
We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.
Today to test the Power Supply we have taken it into our acoustics room environment and have set our SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa) one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.
As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.
KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refrigerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 Player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum
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Noise (dBA)
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75W
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//
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150W
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//
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250W
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//
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350W
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//
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| 455W | // |
No fan, so therefore not relevant for this article. No complaints here !
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Temperature (c)
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Intake
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Exhaust
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75W
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35
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40
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150W
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36
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43
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250W
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39
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48
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350W
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42
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54
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455W
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45
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59
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The high 80 Plus Gold Efficiency and heatsinks ensure that the temperature differential is maintained to a maximum of 14c at full load. Impressive results.
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Maximum load
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Efficiency
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492.6W
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89.26
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Pushing the PSU above its rated limits generates an efficiency level of around 89%. This is not a viable ‘real world’ situation, but its interesting nonetheless.
Great design, but wow thats expensive. 850W are under £100 now.
Not much wrong with this, good efficiency, silent, nice bundle.
They make some great designs, id say 75% of the worlds best PSU designs are seasonic.
One slight problem which is made worse considering its intended application…
Many HTCP/cube cases sit the PSU against the side/top, assuming that the built in fan will push the hot air out of the back. This means that the top of the PSU is placed against a side/top panel with little to no gap (to save space)
As this PSU’s top panel is vented, and needs to be at the top, the side/top panel on the case will block it causing unsufficient ventilation. This means that the PSU can only really be used in more modern tower cases where the PSU is at the bottom.
This seems to me to be somewhat contrary to the intended use, don’t you think??
Hi Martin. You make a very good point. It would depend greatly on the specific chassis design and the air flow of the system. There may be some small physical case designs as you say that might have the top vented panel of the PSU partially blocked.
Hi Z
It wouldn’t be able use in my case for example. OK, it’s a cheap ‘cube’ case, similar to the Thermaltake Armor A30 but without the top fan. The PSU is set at the top of the case, tight against the roof. Also, take a look at the Antec Fusion Remote, the PSU is in it’s own ‘chamber’ (along with the 5.25 drives) with no top venting. And you can’t use this at all with most of the Silverstone Lascala’s and Grandia’s. They have the PSU set on it’s side so it’s a no go.
I don’t mean to do down what is clearly a very good PSU. I’d dearly love to have a fanless PSU in my HTPC.
It seems the only waypossible to use this though is to take a drill/saw to the top of most HTPC cases to create a vent and thus turning what you’s plan to be a pretty box sitting under your TV in to an eye-sore.
I guess much of my complaint is aimed at the case manufacturers that assume that the PSU will have it’s primary vent pushing air out of the back. They ought to have realised, seeing as fanless PSU’s have been around for a ling time, that HTPC case owners might want to use one and factored that in to their desins.
Sorry, I’ve just re-read that and realised I’m ranting a bit! I’ll put that down to my frustration at not being able to get my HTPC quiet enough!
Thanks for the great review!
Its actually a good point and I never thought about the problems as we are generally so focused on the design and performance, rather than the partnering cases available. Something like this would definitely need the vented top directly accessible to air and as you say a fan based PSU would be a safer option with restricted case designs.
There are some other higher output power supplies such as Corsair 750w and 850W models which don’t actually spin the fan until a specific power output is met, therefore in a low powered media center they would be silent, even when loaded (as long as the long variable is inside the limit for silent fan use).
Seasonic told us:
1. The 400/460FL is actually based on the X-850 platform so it can withstand quite a bit of abuse.
2. We have many customers put the PSU on its side without any heat issues because most HTPC system requirements is actually very low.
3. As well, so long as there is air flow movement within the case to the outside, it is enough for the PSU, especially due to the actual low consumption of most HTPC systems.
4. The FL series are all with OTP protection so when Temperature of critical components reaches a certain point, the PSU will shut down to protect itself.
5. All our X & P are hybrid Fanless with differences on to when the fan kicks in at what load points.
Caught one on sale for $100. Placed it upside down in a Lian Li PC V 351 with the side vents taped over so all the case air outflows through the ps. AMD A8 for HTPC. Sits behind TV . I never hear the fans and the outflow is barely warm.
I thought I read somewhere this is an X-750 without the fan. I have used other PS’s but now I only use Seasonics, never had a failure and voltage is rock solid over years of use.
I have read that such a PSU may annoy with a long pi sound, because this is difficult to create such a device. I am curious whether are many product returns? I am looking for a new PSU in vain. I think about buying a Thermaltake, but maybe such a device without a fan would be better?
PC24.de offers it for a pretty good price (although I should check it on Amazon).
I don’t want to send it back and have other troubles if it is not reliable enough.