be quiet! 350w SFX Power PSU

Simulated Load Testing

Simulated Load Testing
 
To provide accurate and consistent results in all of our PSU testing, Overclock3D uses professional grade DC electronic load equipment capable of placing a sustained load of 3690w across a total of six rails (including +5vsb and -12v) on the PSU! This is achieved by using a combination of SunMoon and Analogic electronic load equipment which allow us to adjust amperage loads in increments as small as 0.01A while also measuring voltage and wattage readings on-screen.
 
During today's tests, we will be placing the be quiet 350w SFX PSU under 25%, 50%, 75% and 100% load levels at room temperature. Unfortunately, due to the size of the PSU on test today no 50°C 'hot-box' testing could be performed.
 
be quiet! 350w SFX Results @ Room Temperature
   +3.3v  +5.0v  +12v  +5vSB  -12v  AC Watts /
 DC Watts
 Efficiency  Intake /
 Exhaust
Δ Temp
T1
(Low)
3.75A 4.00A 4.25A  0.62A  0.12A 105w /
88w
 83.80% 27.2°C /
44.2°C
17.0°C
3.37v 5.09v 11.92v 5.14v  -11.90v
T2
(Med)
7.50A 8.00A 8.50A 1.25A  0.25A  205w /
176w
 85.85%  27.0°C /
45.0°C
18.0C
3.35v
5.03v
11.94v 5.05v  -11.93v
T3
(High)
11.25A 12.00A 12.75A  1.87A  0.37A  309w /
263w
 85.11%  26.5C /
45.8°C
19.3°C
3.33v 4.98v 11.94v 4.96v -11.98v
T4
(Full)
15.00A 16.00A 17.00A 2.50A  0.50A 419w /
350w
83.53%  25.6°C /
44.7°C
 19.1°C
3.31v 4.92v 11.96v 4.88v -12.01v
T5
(x-load)
15.00A 16.00A 1.00A 0.00A 0.00A 175w /
138w
78.85% 27.2°C /
45.2°C
18.0°C
3.34v 4.75v 12.45v 5.16v -12.50v
T6
(x-load)
 1.00A  1.00A  29.50A  0.00A  0.00A 0w /
346w
00.00%  00.0°C /
00.0°C
 0.0°C
0.00v 0.00v 0.00v 0.00v -0.00v
T7
(MAX)
 15.00A  16.00A 23.00A  2.50A  0.50A  507w /
420w
82.84%  27.3°C /
56.0°C
 28.7°C
3.31v 4.93v 11.88v 4.86v -12.06v
 
Starting with the results from Test 1-4 which best represent the PSU under normal usage, we can see that the +3.3v and +5v rails on the unit are reasonably stable with a drop of 0.06v and 0.17v respectively. The real shock however comes when we take a look at the results from the +12v rail which actually INCREASED by 0.04v from idle to full load. This normally occurs when the voltage regulation on the PSU overcompensates for the load and can actually end up reducing the total power output as a result. Efficiency, on the other hand is very good for such a small unit with 85% being achieved at a load of 180 - 260w.
 
Although it is quite unlike me to comment on the noise of a PSU given how loud the load testing equipment is, this is undoubtedly going to be an important factor in the decision of anyone purchasing a SFX PSU. Therefore, using my ear alone as the only measuring device, I can tell you that up to 200w load the SFX Power is very quiet. However as the load increases to 260w the 80mm fan speed increases significantly to the point where I imagine you'd easily be able to hear it across the room. At 350w I could actually hear the PSU above the load testing equipment, which is never a good sign! 
 
T5 moves into the cross-load teritory and here we can see that the be quiet isn't so happy with a heavy load on the +3.3v and +5v rails and only a small load on the +12v rail. Voltages for the +5v rail hit a rather poor 4.75v and the +12v rail shoots up to 12.45v. Additionally efficiency during this test drops to around 78%. In T6 the cross-load is reversed with a minimal load being placed on the +3.3v and +5v rails and the rest on the +12v rail.  Unfortunately during this test the be quiet unit refused to power on with anything above 25A on the +12v rail and therefore failed the test. What we do need to remember at this point though is that these cross-load results are highly unlikely to be reproduced by any PC system (especially a HTPC/SFF PC) in the real world. Only if you was intending to use the unit purely to power 12v devices and nothing else would this become an issue.
 
T7 sees the SFX Power hit a maximum output of 420w - 70w higher than that if its rated output. Given the size of the unit this is actually pretty respectable and shows that the unit has a little extra power to give should the need arise. At this load the voltages are still very respectable and efficiency is just shy of 83%.
 
be quiet! 350w SFX Scope Results @ Room Temperature 
   +3.3v  +5.0v  +12v
T1
(Low)
T1_3.3V T1_5V T1_12V
T2
(Med)
t2_3.3v t2_5v t2_12v
T3
(High)
t3_3.3v t3_5v t3_12v
T4
(Full)
t4_3v t4_5v t4_12v
T5
(x-load)
t5_3.3v t5_5v t5_12v
T6
(x-load)
     
T7
(MAX)
T7_3.3 T7_5 T7_12
 
For those of you not familiar with the term 'ripple', this refers to the small fluctuations in voltage that occur in all PSU's on a milisecond scale. Large quantities of 'ripple' on a PSU can damage or kill components in your PC over time and therefore testing a PSU's performance in this area is just as important as any other part. Unfortunately ripple cannot be measured using a standard multimeter and requires a specialist device called an oscillioscope. The results you see above are taken from our Rigol 25Mhz 400MSa/s scope that can save 'screenshots' of its data to a USB memory stick.
 
A quick glance at the graphs above shows the most unruly rail to be the +3.3v one. However, even here the SFX Power manages to keep the ripple at just over 40mVpp in Test 4 and just under 40mVpp in Test 7. The +5v and +12v rails perform even better in comparison topping out at 21.6mVpp and 25.6mVpp respectively during Test 4. Only during the cross-load testing in T5 does the +5v rail break 50mVpp showing that the SFX Power isn't too keen on cross-load situations.
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Most Recent Comments

22-09-2009, 13:13:09

JN
"Looking for a quality small form factor PSU to replace the generic grey deathtrap that came with your HTPC chassis? Read on to see if be quiet! have the answer."

http://www.overclock3d.net/gfx/artic...155848146s.jpg

be quiet! 350w SFX Power PSU

22-09-2009, 13:22:50

PeterStoba
Very nice unit that, the size of it is great, whilst performance is sitll good. Looks nice as usual too!

Shame it's noisy at full load, but for the applications it's aimed at, will it ever reach full load?

22-09-2009, 13:43:55

VonBlade
My initial thoughts were that they've done really well to get it so small, but it's a shame about the noise. Then exactly like Peter I wondered how likely it is for a HTPC system to hit full load.

Depends on if you use it for Bluray playback (thus a beefy CPU) or not I guess.

22-09-2009, 14:37:59

zak4994
Perfect timing.

Need a HTPC PSU as my relative's HTPC PSU just busted!

Gotta love OC3D.

22-09-2009, 15:14:49

JN
Quote:
Originally Posted by name='zak4994'
Perfect timing.

Need a HTPC PSU as my relative's HTPC PSU just busted!

Gotta love OC3D.
Glad to be of service

@Peter/VB, yeah I doubt in most systems it will come close to 350w so the high load noise won't really be too much of an issue. But on the other hand I do have a Q6600 HTPC with a HD4850 and 3x1TB HDD's, so I might give it a slightly hard time

22-09-2009, 15:15:40

zak4994
Just wanna make sure before I order, will this fit in an HP Slimline PC?

Don't wanna thread hijack. lol

22-09-2009, 15:22:12

JN
Quote:
Originally Posted by name='zak4994'
Just wanna make sure before I order, will this fit in an HP Slimline PC?

Don't wanna thread hijack. lol
If it takes a standard SFX PSU then yeah I'd say so. We can compare measurements if you're not sure tho

22-09-2009, 16:25:03

VonBlade
Lol. That's a hell of a HTPC Jim!

I still find the size of the thing amazing. As so many PC parts are getting enormous (men and their size fetish eh) it's great to see some companies going in the opposite way.

I'd love to see how it looks in size against the PCP&C behemoth

23-09-2009, 10:26:20

Rastalovich
It all really depends if ur buying all the components for a htpc, or ur using gear u have lying about to make one.

The size, or shape, of the unit here wouldn't fit into the htpc I've got at present. It's more the shape of a squashed vhs-video unit - to that extent, the options are to really go with what is supplied with the case. It works, can't remember off-hand if it's 300/350/400 (might be a CiT), but it is a p4 designed psu, with optional replacements coming in the shape of some obscure ebuyer.co.uk stockers. 4 pins to the Q35m mobo has worked to this point.

So really, even with the psu being aimed at the smaller case market, u do have to consider the cases this could limit u to.

Imo too, being as this will not be used (or meant for should I say, cos people do some strange things) in some enthusiasts oc'ing, large graphics, loads of drives, rig - it has a limited appeal to the small case people that I don't think warrants a costing of 45 necessarily.

Having said that, it performs close to the quality of a regular atx of similar wattage. Therein lies the reason u would have to submit.

More than anything tho, I like the idea that the option is out there. Too many things pop-up during custom builds, that hamper what u might want to do. Having the shorter depth is great without the loss of quality.

Great stuff.

(another thing this will be good for is replacement psus for dell/compaq etc builds that often have a small-depth psu in them. if u try a regular one in them, u find the dvd drive doesnt fit. great option)

25-09-2009, 04:23:06

VonBlade
Wouldn't this be perfect as the second power-supply in a WC system!

Just thought of that.

25-09-2009, 04:33:50

JN
Quote:
Originally Posted by name='VonBlade'
Wouldn't this be perfect as the second power-supply in a WC system!

Just thought of that.
Yep. It may be a bit old school now but I was also thinking that it would make quite a good TEC/Pelt PSU.
Reply
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