Be Quiet! Dark Power Pro P11 550 W: from gold to platinum

Conclusion and evaluation

The Be Quiet! Dark Power Pro P11 550 W passed the combined and crossload testing in accordance with the ATX specification, so according to my evaluation methodology, it is deserving of its evaluation. I can’t help but to compare this unit to the Corsair RM550x, which is cheaper by at least 1/3. Don’t get me wrong, the voltage regulation was very good, but definitelly inferior to that of the RM550x (mostly within ±2 %, but 6 % for -12 V). However, the ripple suppression is slightly better, as all positive rails stood just within 20 mV or 40 %. The efficiency is better as this is an 80 PLUS Platinum certified unit, but albeit somewhat lower than what it should be – and I think now we can clearly say that my new wattmeter’s margin of error tends to be a bit generous, as it measures on the higher side of things. So I think this unit should be able to peak at around 94 % efficiency.

Besides a couple of Toshin Kogyo capacitors (a brand that I don’t particularly trust), the P11 550 W is equipped with only quality capacitors (I believe we can trust C(r)apXon polymers to survive at least as long as japanese wet electrolytics) and comes with almost fully modular cabling, the only fixed wiring being that of the Main ATX cable. And while the fan doesn’t operate semi-passively as the ones in Corsair RMx units do, it spins so slowly that it shouldn’t make any difference. However, I believe it is somewhat detrimental to the internal operating temperature (which seems to be the Be Quiet!’s philosophy though). Unless you run the unit in a very hot environment, it should be OK, especially considering that this is the first Be Quiet! unit with quality capacitors that I have ever held in my hands.

But I am then compelled to address another drawback: unlike other manufacturers of such undisputed high-end units, Be Quiet! only offers a five-year warranty while others offer 7 years or sometimes even a 10 year warranty. Now if the unit cost 1000 CZK less, then that would be acceptable. But for such a high price you should not expect any compromise. After all, you can buy a fanless 520 watt Seasonic for similar price with longer warranty! So while technically this unit is not bad and not even average, in fact it really is above average – in my opinion you are not getting enough for what you are being asked to pay for it. There are units out there that offer better value for their price.

The integrated fan speed controller feature, which drives external fans with the same voltage as the units built-in fan, is not alone in itself that unique a feature to warrant its pricetag. Having said all this, this unit may perhaps have one saving grace: While I don’t typically evaluate the number of cable connectors or their length, I must commend Be Quiet! for including sufficiently long cables that are plentiful in number. Short cables plague many competing units…

The value of the Be Quiet! Dark Power Pro P11 550 W as a high-end unit is as follows:

  • components used: 0 p. (− for non-quality capacitors, − for lack of golden-plating)
  • built quality: 2 p. (− for solder balls and messy soldering)
  • voltage regulation: 1 p. (- for combined loading, – for crossloading)
  • ripple: 13 p. (+ for combined loading, + for crossloading)
  • efficiency: 17 p. (+ for higher stand-by efficiency, + for higher combined-loading efficiency, + for crossload efficiency)
  • hold-up time: 12 p. (+ for longer voltage hold-up time)
  • others: 9 p. (+ for modular cabling, + for cable ties, + for longer warranty)

It really is a pity that the -12 V rail’s performance was so average, because if it was better the unit could have gotten much better results. Overall I like it, but the value isn’t so good and with its terrible price…I can only give a Bronze award this time.



Assuming the cost is 4300 CZK, then the price per value ratio would be 100×54/4300 = 1.26. So after six high-end units, we can see that the Be Quiet! Dark Power Pro P11 550 W is second in value. However, considering the price per value ratio, compared to only a percent worse Cooler Master V Semi Modular 550 W, is is up to 100 % worse.

Unit Value (high-end)
Corsair RM550x 85.5
Be Quiet! Dark Power Pro P11 550 W 54
Cooler Master V Semi Modular 550 W 53
Antec Earthwatts Platinum 550 W 22.5
SilentiumPC Supremo M1 Gold 550 W 10
Silverstone Strider Essential Gold 600 W 4
Pros + high overall efficiency
+ silent (very slow fan) + integrated fan regulator
+ low ripple
+ great voltage regulation (besides -12 V rail)
+ almost fully modular
+ longer warranty
+ long cables
Cons worse -12 V regulation
may run a little warmer
Be aware of… /?\ average hold-up time


I thank the Be Quiet! company for providing the Be Quiet! Dark Power Pro  P11 550 W unit.


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