be quiet! Pure Power 9 600W PSU Review

be quiet! released the updated Pure Power 9 series that consists of four semi-modular models with capacities ranging from 400W to 700W. Today, we're looking at the 600W implementation to see where it stands in the competitive mainstream market.

By Aris Mpitziopoulos
published

Early Verdict

be quiet!'s Pure Power 9 600W PSU is a very silent power supply based on a platform that doesn't offer good performance when the loads are highly unbalanced among the +12V and 5V rails. Efficiency is good though and with a price lower than $70 it will be highly competitive.

Pros

  • +

    Full power at 47 °C • Low ripple at +12V • Long hold-up time • Silent • Efficient for a Silver unit • 4x PCIe connectors • Flat and stealth modular cables • Compact dimensions

Cons

  • -

    Cross Load performance • Performance of the 3.3V rail in Transient Tests • Power Good signal drops late • High inrush current • Low quality bulk cap • Long component leads • Single EPS connector • Power distribution • 5VSB efficiency

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Introduction

be quiet! is a well-known German company with a diverse portfolio of PSU products. As you might guess from its name, be quiet!'s focus is on delivering acoustically-friendly power supplies, and indeed the company's PSUs are some of the quietest you can buy.  During this year's CES, we had the chance to check out the new Pure Power 9 series. These budget-oriented units, manufactured by FSP, feature 80 PLUS Silver efficiency.

The previous Pure Power 8 models were 80 PLUS Bronze-rated, so these new PSUs are certainly an upgrade, boasting a more advanced platform. Those older units utilized a group regulation scheme along with SBRs for rectifying the +12V rail, while the new ones use a synchronous design for +12V regulation and, according to be quiet!, independent regulation of the minor rails. The platform upgrades don't stop there. Solid caps are used for increased reliability and a GTD (gas discharge tube) takes the MOV's place providing over-voltage protection. Frankly, we're not sure that GTDs offer better protection than MOVs; they can withstand higher currents and have lower capacitance, but they're also slow and cause a short circuit once triggered, allowing high currents to flow instantly.

We received the 600W Pure Power 9 (L9-CM-600W) for testing. It sports two +12V rails, and be quiet! claims the PSU is silent even under full load. Its fan has a max speed of 1800 RPM, so obviously the control circuit needs to stay conservative, else it wouldn't facilitate low noise output under high operating temperatures. Without question, the efficiency improvement over last-gen's implementation helps enable this since greater efficiency translates to less heat waste.

Specifications

be-quiet! L9-CM-600

The L9-CM-600W is 80 PLUS Silver-rated; we don't review many power supplies with the Silver certification, but we know it's a step up from Bronze, particularly for folks on a budget. You also get the benefit of semi-modular cabling, compatibility with the C6 and C7 sleep states (Haswell-ready) and a maximum operating temperature of 40 °C for full power delivery. Additionally, the PSU includes all of the protection features we'd expect, while our sources indicate that the cooling fan has a sleeve bearing. We couldn't hope for much more in an inexpensive power supply. There is no semi-passive mode unfortunately, but the fan profile isn't aggressive, minimizing noise under normal conditions. Finally, you get a three-year warranty, which is ample in this segment.

Power Specifications

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Rail3.3V5V12V112V25VSB-12V
Max. PowerAmps2518322830.3
Watts140576153.6
Total Max. Power (W)600

There are two +12V rails, the first delivering 4A more than the second one. In total, both +12V rails can output 576W, or 96 percent of the unit's maximum. The minor rails also have unequal peak power ratings, as the 3.3V rail delivers more amps than the 5V rail. It seems as though be quiet! wanted to keep the 5V rail's max output low in order to avoid putting huge stress on the +12V rails, since they seem to be regulated together (despite the company's claims that they're independent). Finally, the 5VSB rail is strong enough, with 3A of maximum current output.

Cables And Connectors

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Native Cables
DescriptionCable CountConnector Count (Total)
ATX connector 20+4 pin (550mm)11
4+4 pin EPS12V (600mm)11
Modular Cables
6+2 pin PCIe (500mm+150mm)24
SATA (500mm+150mm+150mm)13
SATA (500mm) / Four-pin Molex (+150mm+150mm)12
SATA (500mm+150mm) / Four-pin Molex (+150mm) / FDD (+150mm)12 / 1 / 1

Cable length is ample, as is the distance between connectors. Usually we complain when there's more than 10-11cm between the SATA connectors. However, lately we've noticed cases with SSD mounting locations spread farther apart.

The number of available connectors is more than enough for a budget 600W unit, and the only restriction is a single EPS connector. Then again, we doubt that anyone will put a power supply like this one in a PC with a high-end motherboard requiring two EPS connectors. Finally, all connectors use standard 18-gauge wires.

Power Distribution

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Power Distribution
12V1ATX, Peripheral, PCIe 1+2
12V2EPS, PCIe 3+4

Since there are only two +12V rails, some compromises were made. But we don't agree with putting one EPS connector and two PCIe connectors together on the second +12V rail. It would be better if the EPS connector instead shared that rail, which is weaker, with the ATX and peripheral connectors, moving the auxiliary PCIe connectors to the first +12V rail.

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Aris Mpitziopoulos
Aris Mpitziopoulos
Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.

14 Comments Comment from the forums
  • turkey3_scratch
    Really poor unit. For one thing, the crossload performance is poor. Sleeve bearing fan with less reliability. 85C primary capacitor. Once again, another failed 3.3V transient response. Very high inrush current. Also, near worst of all, 140+mv of ripple on the 12V rail in CL2. Just really bad. And CL2 is a realistic scenario these days because those 3.3V and 5V rails don't do much anyway. FSP's soldering is clearly not the same as the nice soldering on their high end units.

    But my largest complaint would have to be voltage regulation (line regulation) under different load scenarios on page 6.
    Reply
  • 4745454b
    85C main cap doesn't bother me that much. It should get airflow from the fan so unless the fan dies (and if it does 105C cap isn't going to help much.) or it gets clogged with dust you should be ok. As for the CL test what do you expect? It's a group regulated design so that's going to happen. It's like buying a super duty truck and then complaining you don't get 30MPG in town. What I find more bothersome is they can't seem to sell you what they claim on the box. If it's not C6 or C7 ready and not a group reg design, why claim so? I wonder if they shipped the wrong unit?
    Reply
  • powernod
    Outstanding review by Aris as always! :)
    If only the PSU itself was outstanding as well:ouch:
    Reply
  • basroil
    Looks like FSP is still mostly a second tier manufacture with those transient response and inrush... does it really hurt that much to put a shuntable thermistor like Seasonic and SuperFlower units have?

    For less than $10 more you can usually find excellent Seasonic and SuperFlower Leadex Gold units, which makes it really hard to say this PSU is anything more than "meh"
    Reply
  • Aris_Mp
    actually I am worried about the bulk cap, because 85C means that it has 4x times lower lifetime than a 105C cap.
    Reply
  • turkey3_scratch
    17839248 said:
    85C main cap doesn't bother me that much. It should get airflow from the fan so unless the fan dies (and if it does 105C cap isn't going to help much.) or it gets clogged with dust you should be ok. As for the CL test what do you expect? It's a group regulated design so that's going to happen. It's like buying a super duty truck and then complaining you don't get 30MPG in town. What I find more bothersome is they can't seem to sell you what they claim on the box. If it's not C6 or C7 ready and not a group reg design, why claim so? I wonder if they shipped the wrong unit?

    Not all group regulated designs are exactly the same way. We see in Seasonic's S12ii series a group regulated design that actually crossloads very well. This seems to be one of the worst on the ladder.

    @Aris: Why is Inactive PWR_OK to DC_LOSS better at a higher value? Once the PWR_OK signal is dropped, wouldn't you want the unit to shut down as quickly as possible, not prolong it?
    Reply
  • powernod
    It was already explained by Aris at his review:
    "The power-good signal lasts longer, so when it drops, the voltage level of the +12V rail is already below 11V."
    When the pwr_ok to DC_loss is higher (*meaning that it has a positive , not negative value) that means that the motherboard will already have been shut-down. (*from what i've understand, at least)
    Reply
  • turkey3_scratch
    Not sure how the motherboard could shut down before the PWR_OK signal is dropped.
    Reply
  • Aris_Mp
    the problem is that in some PSUs, PWR_OK, which informs the mainboard when it should shut down, drops after and not before the rails go our of spec. So once it drops the rails are already too low.

    Normally when AC is removed, the PWR_OK signal should be de-asserted at least 1ms before voltages go out of spec in order not to stress the VRMs of the mainboard and of other components (e.g. VGA, HDD, SSD, etc.).

    The only way to address this issue is to have a circuit on the mainboard checking the input voltages and give the shut down order when these go out of spec. In other words to completely bypass the power_ok signal coming from the PSU. But this will cost money and after all a PSU oughts to follow ATX spec's guidelines.
    Reply
  • turkey3_scratch
    So is "DC_LOSS" considered "voltages out of spec"? I mean, there can still be DC even if voltages are out of spec. It won't be a loss of DC< just an out-of-spec voltage relative to the DC.
    Reply