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be quiet! Straight Power 11 550W Platinum Power Supply Review

The new Straight Power 11 model with 550W max power is now certified as 80 PLUS Platinum and features a dead silent operation.

be quiet! Straight Power 11 550W Platinum
(Image: © Shutterstock, be quiet!)

The new Straight Power 11 Platinum line focuses more on noise output than performance, which is expected from be quiet! It's not that the overall performance is low, but we expected to see a larger difference with the previous model, given the platform upgrades that boosted efficiency. Unfortunately, the new unit has a downgraded 5VSB circuit with notably lower efficiency than the previous model, and the Vampire power levels are high with both voltage inputs. 

The parts that FSP used in this platform are of high quality, especially the bulk caps of the APFC converter. It is the first time that we see a 5000h lifetime bulk cap in a desktop PSU, with the majority of units using 2000h bulk caps. It is also nice to see 16AWG gauges used on the ATX and EPS connectors of a 550W PSU, and the cable length is fully satisfactory. Moreover, this is one of the few power supplies that has an adequate distance between all of its peripheral connectors (both SATA and 4-pin Molex ones). Usually, the distance between those connectors is 100-120mm, leading to compatibility issues even with mid-size cases. 

(Image credit: Tom's Hardware)

The FSP platform that the Straight Power 11 Platinum 550W uses has potential, but we noticed several issues that not only affect the overall performance but can also bring trouble in extreme scenarios. We are referring to the protection features, where the OCP triggering points on all rails are set too high. The same goes for the over-power protection, which shuts down the PSU at around 793W. 

Under normal operating temperatures, the PSU might survive such high loads, but at higher temperatures (>40 degrees Celsius), this could lead to its destruction. The competition is fierce in this Wattage and price range, with the Fractal Design Ion+ 560P offering higher overall performance, ultra-flexible cables, and equally quiet operation. The Seasonic Focus Platinum 550W and the Corsair RM550x units also achieve notably better performance and feature silent operation. 

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Disclaimer: Aris Mpitziopoulos is Tom's Hardware's PSU reviewer. He is also the Chief Testing Engineer of Cybenetics and developed the Cybenetics certification methodologies apart from his role on Tom's Hardware. Neither Tom's Hardware nor its parent company, Future PLC, are financially involved with Cybenetics. Aris does not perform the actual certifications for Cybenetics.

Aris Mpitziopoulos
Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.
  • JohnBonhamsGhost
    how can it be both;

    + FORCompatible with the alternative sleep mode

    &

    - AGAINSTNot compatible with the alternative sleep mode

    ??
    Reply
  • chaz_music
    Great write up, Aris.

    I was not aware that the Intel PSU specs were coming out this summer (July 2020), which is great. BTW, take a look at the ripple graph on page 3. I think the Y axis is labelled wrong. Also, why no data on the 115VAC holdup? That is critical for people using this PSU with a standard UPS. Most of desktop UPS systems (think: inexpensive) are standby / line interactive and have a change over relay with transfer times in the 4-20mSec time range. Any PSU that is lower than that will have problems keeping the CPU alive during an outage. Too bad there is not a signal from the PSU to the CPU to power back. That signal could be used everywhere to cause SSDs and RAID arrays to go into save mode, and other subsystems to power down (Ethernet, USB, audio, etc.).

    The Cybernetics Labs testing methods are spot on for the "how and why". There are minor tweaks that I would make, but overall, excellent testing methodology. The UPS market has cheated on efficiency for decades by testing a cold UPS for the product documentation. Everything should be at thermal steady state for true efficiency numbers, and at realistic operating conditions. The only parts that benefit from being warm are the electrolytic caps, except for their lifetime. I believe it is still true that all electrolytic caps have a decrease in ESR as they get warmer, up to a point depending on the electrolyte used. Everything else gets worse efficiency with heat: MOSFETS, XFMR, filter inductors, etc.

    It is good to see better efficiency numbers in lower power PSUs. I searched for along time on my NAS build for at least a 80+ gold rated 200-250W PSU. I finally found an FSP 250W unit that was in an SFX package. A great article would be one who has the better/best low power PSUs especially in the area of efficiency.

    Several points that I believe get overlooked in thinking about efficiency:

    How much energy are you going to use to cool the building that the PSU is in? Usually around 50% of the total PSU power used for the months that HVAC is being used. This also gets overlooked with cost comparisons for LED bulbs versus incandescent bulbs. The HVAC savings is enormous.
    The concept that the payback period for a higher cost efficient PSU does not give good ROI. I reuse most of my PSUs unless the caps look poor or I have had it being used at over 50-60% rated power for much of its life. With PSU getting warranties of 5years+, the added cost should be amortized over a longer period. Maybe over two chassis builds?
    Thanks for the great article.

    BR,
    Charles
    Reply
  • Aris_Mp
    JohnBonhamsGhost said:
    how can it be both;

    + FORCompatible with the alternative sleep mode

    &

    - AGAINSTNot compatible with the alternative sleep mode

    ??
    this is an obvious error. It IS compatible with the alternative sleep mode. Already asked to fix this.
    Reply
  • Aris_Mp
    chaz_music said:
    Great write up, Aris.

    I was not aware that the Intel PSU specs were coming out this summer (July 2020), which is great. BTW, take a look at the ripple graph on page 3. I think the Y axis is labelled wrong. Also, why no data on the 115VAC holdup? That is critical for people using this PSU with a standard UPS. Most of desktop UPS systems (think: inexpensive) are standby / line interactive and have a change over relay with transfer times in the 4-20mSec time range. Any PSU that is lower than that will have problems keeping the CPU alive during an outage. Too bad there is not a signal from the PSU to the CPU to power back. That signal could be used everywhere to cause SSDs and RAID arrays to go into save mode, and other subsystems to power down (Ethernet, USB, audio, etc.).

    The Cybernetics Labs testing methods are spot on for the "how and why". There are minor tweaks that I would make, but overall, excellent testing methodology. The UPS market has cheated on efficiency for decades by testing a cold UPS for the product documentation. Everything should be at thermal steady state for true efficiency numbers, and at realistic operating conditions. The only parts that benefit from being warm are the electrolytic caps, except for their lifetime. I believe it is still true that all electrolytic caps have a decrease in ESR as they get warmer, up to a point depending on the electrolyte used. Everything else gets worse efficiency with heat: MOSFETS, XFMR, filter inductors, etc.

    It is good to see better efficiency numbers in lower power PSUs. I searched for along time on my NAS build for at least a 80+ gold rated 200-250W PSU. I finally found an FSP 250W unit that was in an SFX package. A great article would be one who has the better/best low power PSUs especially in the area of efficiency.

    Several points that I believe get overlooked in thinking about efficiency:

    How much energy are you going to use to cool the building that the PSU is in? Usually around 50% of the total PSU power used for the months that HVAC is being used. This also gets overlooked with cost comparisons for LED bulbs versus incandescent bulbs. The HVAC savings is enormous.
    The concept that the payback period for a higher cost efficient PSU does not give good ROI. I reuse most of my PSUs unless the caps look poor or I have had it being used at over 50-60% rated power for much of its life. With PSU getting warranties of 5years+, the added cost should be amortized over a longer period. Maybe over two chassis builds?Thanks for the great article.

    BR,
    Charles

    Hi Charles, and thank you for your comments.

    The hold-up time is almost identical between 115V and 230V. The change is in the inrush current. I agree with you, the hold-up time is of immense importance.

    CL ripple graph in page 3, I cannot find anything out of order.

    If you have any suggestions on how to improve the Cybenetics methodology, they always hear opinions and are ready to make changes, if those are for the best.

    About efficiency, diodes have lower voltage drops at increased temperatures as well, and this plays a major role especially in bridge rectifiers.

    Thank you for the other two points you mention. Indeed the cost of dealing with the added thermal load of lower efficiency PSUs is significant.
    Reply
  • Co BIY
    Interesting cross-hatching (in solder?) on the back of the board in the FET and VRM photo.

    Can someone explain the purpose of that ? Heat Sink ? Heat dissipation ?
    Reply