Corsair RM550x Power Supply Review

Efficiency, Temperature And Noise

Efficiency

Our efficiency testing procedure is detailed here.

Using the results from the previous page, we plotted a chart showing the RM550x efficiency at low loads, and loads from 10 to 110 percent of the PSU's maximum-rated capacity.

Under normal loads, the RM550x takes the lead from all of the other Gold-rated units. It loses only to the two Platinum units in our comparison graph. Although the deficit to Super Flower's Platinum platform is rather small, the passive Seasonic SS-520FL is way ahead with an impressive 1.68% difference.

Corsair's offering performs well under light loads, but most of the competing platforms are even more efficient. Without question, the efficiency champion in these situations is Cooler Master's V550S, which surpasses the 90% mark.

Efficiency At Low Loads

In the following tests, we measure the RM550x's efficiency at loads significantly lower than 10 percent of its maximum capacity (the lowest load the 80 PLUS standard measures). The loads we dialed were 20, 40, 60 and 80W. This is important for representing when a PC is idle, with power-saving features turned on.

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)Fan NoisePF/AC Volts
11.203A0.490A0.480A0.195A19.6169.61%00 dB(A)0.843
12.122V5.020V3.315V5.013V28.17115.1V
22.434A0.989A0.995A0.395A39.7380.44%00 dB(A)0.914
12.117V5.018V3.313V5.007V49.39115.1V
33.665A1.486A1.510A5.002A59.8384.76%00 dB(A)0.946
12.112V5.017V3.312V5.002V70.59115.1V
44.888A1.994A1.991A0.801A79.7787.05%00 dB(A)0.967
12.107V5.015V3.310V4.996V91.64115.1V

Under light loads, the RM550x operates passively, outputting zero noise. Efficiency drops below 70% in the first test, and in the second it barely manages to pass 80%. Only in the last two tests does this PSU start showing its potential, registering high enough efficiency levels.

5VSB Efficiency

The ATX specification states that 5VSB standby supply efficiency should be as high as possible, recommending 50 percent or higher with 100mA of load, 60 percent or higher with 250mA of load and 70 percent or higher with 1A or more of load.

We take four measurements: one each at 100, 250 and 1000mA, and one with the full load the 5VSB rail can handle. 

Test #5VSBDC/AC (Watts)EfficiencyPF/AC Volts
10.101A0.5177.27%0.067
5.069V0.66115.1V
20.252A1.2881.01%0.147
5.064V1.58115.1V
31.002A5.0681.22%0.324
5.045V6.23115.1V
43.002A14.9979.65%0.424
4.994V18.82115.1V

The 5VSB rail is highly efficient. We'd be even more impressed if we hadn't already seen the amazing performance of FSP's HG650, though.

Power Consumption In Idle And Standby

Mode12V5V3.3V5VSBWattsPF/AC Volts
Idle12.130V5.026V3.319V5.026V7.750.487
115.1V
Standby0.050.005
115.1V

In the table above, you'll find the power consumption and voltage values of all rails except -12V when the PSU is idle (powered on, but without any load on its rails), and the power consumption when the PSU is in standby mode (without any load, at 5VSB).

Energy consumption at standby is very low with both voltage supply/input (115V and 230V).

Fan RPM, Delta Temperature And Output Noise

Our mixed noise testing is described in detail here.

The first chart below illustrates the cooling fan's speed in RPM, and the delta between input and output temperature. The results were obtained at 36 °C (96.8 °F) to 48 °C (118.4 °F) ambient temperature.   

The next chart shows the cooling fan's speed (again in RPM) and output noise. We measured acoustics from one meter away, inside a small, custom-made anechoic chamber with internals completely covered in sound-proofing material (be quiet! Noise Absorber kit). Background noise inside the chamber was below 18 dB(A) during testing, and the results were obtained with the PSU operating at 36 °C (96.8 °F) to 48 °C (118.4 °F) ambient temperature. 

The following graph illustrates the fan's output noise over the entire operating range of the PSU. The same conditions of the above graph apply to our measurements, though the ambient temperature was between at 28 °C (82.4 °F) to 30 °C (86 °F).  

Acoustically, this PSU has more in common with its passive competition. If you need one of the quietest 550W power supplies available, the RM550x should be on your short list.

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36 comments
    Your comment
  • SR-71 Blackbird
    I just wish they would get the price down , these are a great lineup \ RX.
    1
  • basroil
    From the performance it seems like CWT is finally something to consider... It's showing Leadex Gold/Seasonic levels of performance.
    0
  • SR-71 Blackbird
    I love the RMX and RMI series , price just keeps me away from the purchase , very very solid.

    Knock a little off the price and these would fly out of warehouses.
    2
  • William Henrickson
    They were on sale when new. I snagged an RM750i for $105 -w- shipping
    0
  • SR-71 Blackbird
    Yeah the 550w should be about 79.99 to 89.99 , no rebates.

    Then I would grab a few.
    0
  • JQB45
    Quote:
    Yeah the 550w should be about 79.99 to 89.99 , no rebates.

    Then I would grab a few.


    Corsair RMx 550W 80+ Gold Certified Fully-Modular ATX Power Supply
    http://pcpartpicker.com/part/corsair-power-supply-cp9020090na
    $79.99

    $89.99 for the 650W version.

    UPDATE:

    Sorry thats with mail in rebates...
    0
  • SR-71 Blackbird
    I don't do rebates , takes to long , and maybe you get it maybe you don't , I'll wait for a newegg drop.
    2
  • Nintendork
    We really need more platinum/titanium PSU's at 300-500w. Most PC's stays near idle and with the efficiency focused gpu's/cpu's they rarely exceed 100w unless you tax them.
    3
  • turkey3_scratch
    Plus companies often don't even send you the rebates, sometimes they just say it was too late or some other bull crap like that. I agree with Blackbird. I've been waiting for a review of the 550 RMx, and what I get out of this review is that it trades blows with the 550 G2 that saying one or the other is better is just silly and extremely nit-picky. They are both incredible. Both offer a 7 year warranty, as only higher-wattage G2s offer the 10 year warranty. They are just so close, that when it comes to picking the better one, the cheaper one is better, and the G2 is cheaper.

    I've actually quit including rebates in my pcpartpicker lists. They are a pain and I don't think they reflect the true cost of an item.
    0
  • turkey3_scratch
    Anonymous said:
    We really need more platinum/titanium PSU's at 300-500w. Most PC's stays near idle and with the efficiency focused gpu's/cpu's they rarely exceed 100w unless you tax them.


    I wish so, but unfortunately if this were to happen they would end up priced the same as any Platinnum/Titanium 650W unit. It's just the way it works. Quality low-wattage models are priced almost the same as the higher-wattage models. I would like to see something like a Titanium 250W model come out from Seasonic. Something like $40, fully modular. Will never happen, though.
    0
  • logainofhades
    Yea the price for these is a big turn off. It is selling at a price that the Evga G2 750w is often seen at. The Evga P2 650w even sells for less. There are quite a few Seasonic and Superflower based units, cheaper than this, actually.
    0
  • turkey3_scratch
    The Seasonic Platinum Series is quite expensive, and much of the X-Series is not even sold anymore. Only the S12ii comes to my mind as an option under $60.
    0
  • logainofhades
    The cheapest RM550x is $99, before rebate, at newegg. You can get a G2 and P2 Evga for same or less. Seasonic 550g is selling for $69. Even if I needed a fully modular unit, there are less expensive models from Evga, XFX, and Antec. For a few $$ more, I can get a GS 850w or a G2 750w. The pricing on this unit is just not good enough to compete. Even their own 650w RMX is only about $10 more.

    http://pcpartpicker.com/parts/power-supply/#e=5,4&W=550,2000&sort=a9&page=1&m=52,11,14,71,39&p=1,2
    0
  • turkey3_scratch
    Well I know that's what I said, I can't find a good argument as to why one should purchase the RMx for $20 more than the EVGA G2, so I just don't recommend it.
    0
  • powernod
    I've got one very good reason for you: The fantastic performance of Corsair's /CWT's platform at the new "Power-OK signal" tests that Aris added at his reviews. On the contrary, the performance of Leadex's platform (*in which EVGA's G2 units are based) in these tests is very discouraging ( http://www.tomshardware.com/reviews/super-flower-leadex-gold-550w-power-supply,4416-4.html )
    2
  • logainofhades
    Still cannot see spending $99 on a 550w Corsair, when I can get a 650w P2, for the same price. Heck, the Seasonic built GS 850w is selling for a mere $3 more.
    0
  • turkey3_scratch
    Yes G2 hold-up time is 12ms whereas ATX spec is 16ms, but that doesn't mean the PSU is going to cause damage to the computer, it just means that if there is AC loss for 12ms the computer will shut down, as the PSU won't be able to maintain the DC. Better hold-up time is not worth the additional $20, especially if you're not running something like a server, in which you would have a UPS anyway that quickly kicks on the battery power in 12ms or less (you'd do research to buy one that does so, as some may be higher than 12ms).

    I'd say the hold-up time is a small gripe and not enough for a $20 more PSU. If hold-up time as super important, every PSU reviewer site would test it like Jonnyguru.
    0
  • powernod
    Quote:
    Better hold-up time is not worth the additional $20, especially if you're not running something like a server, in which you would have a UPS anyway that quickly kicks on the battery power in 12ms or less (you'd do research to buy one that does so, as some may be higher than 12ms).


    Indeed, those who have a good UPS to protect their system, they shouldn't worry about that, but if you don't have a UPS, this failure at Hold-UP time /Power-OK signal, could be very dangerous.
    1
  • turkey3_scratch
    Anonymous said:
    Quote:
    Better hold-up time is not worth the additional $20, especially if you're not running something like a server, in which you would have a UPS anyway that quickly kicks on the battery power in 12ms or less (you'd do research to buy one that does so, as some may be higher than 12ms).


    Indeed, those who have a good UPS to protect their system, they shouldn't worry about that, but if you don't have a UPS, this failure at Hold-UP time /Power-OK signal, could be very dangerous.


    How would hold-up time be dangerous?
    0
  • powernod
    I didn't say only Hold-up Time, I was referring at Aris's new test for Power-OK signal. Take a look of one of his analysis : " The hold-up time tests don't go well. Not only is the measured hold-up less than 16ms (the ATX spec's minimum), but the Power_OK signal drops after, and not before, the PSU's rails go out of spec. This means that your motherboard gets a false power-good signal from the PSU. Indeed, we measured the +12V rail floating at around 10.8V when Power_OK dropped to zero. This is a very low voltage level that applies lots of stress to the voltage regulators of components fed by +12V " ( http://www.tomshardware.com/reviews/super-flower-leadex-gold-550w-power-supply,4416-4.html )
    0