Corsair RM550x Power Supply Review

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Load Regulation, Hold-Up Time And Inrush Current

To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units. 

Primary Rails And 5VSB Load Regulation

Load Regulation testing is detailed here.

Hold-Up Time

Our hold-up time tests are described in detail here.

Our hold-up time measurement easily passes 17ms. Further, the power-good signal is longer than the ATX specification's 16ms minimum recommendation. This unit's single bulk cap is obviously up to the task, and it doesn't hold Corsair's RM550x back in these crucial tests.

Inrush Current

For details on our inrush current testing, please click here.

In most cases, the inrush current is pretty low. We had to repeat the corresponding test multiple times to get the readings depicted on our graphs. Although the thermistor used for inrush current protection is small, it does a good job without using a bypass electromagnetic relay.

Load Regulation And Efficiency Measurements

The first set of tests explores voltage rail stability and efficiency. The applied load equals (approximately) 10 to 110 percent of the supply's maximum in increments of 10 percentage points.

We conducted two additional tests. During the first, we stressed the two minor rails (5V and 3.3V) with a high load, while the load at +12V was only 0.10A. This test reveals whether a PSU is Haswell-ready or not. In the second test, we determined the maximum load the +12V rail could handle with minimal load on the minor rails.

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Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)Noise (dB[A])Temps (In/Out)PF/AC Volts
12.739A1.994A1.990A1.001A54.7783.99%0048.04 °C0.944
12.114V5.017V3.312V4.993V65.2139.55 °C115.1V
26.522A2.990A2.990A1.200A109.7888.58%0048.85 °C0.978
12.100V5.013V3.308V4.988V123.9440.18 °C115.1V
310.658A3.497A3.507A1.403A164.9090.01%0050.33 °C0.987
12.085V5.010V3.305V4.981V183.2041.40 °C115.1V
414.798A3.994A3.997A1.605A219.8090.56%0051.70 °C0.993
12.071V5.008V3.300V4.975V242.7142.45 °C115.1V
518.607A4.988A5.001A1.810A274.7790.56%0052.98 °C0.994
12.056V5.004V3.298V4.969V303.4143.73 °C115.1V
622.423A6.001A6.010A2.011A329.7590.14%58020.843.38 °C0.995
12.040V4.999V3.294V4.964V365.8151.16 °C115.1V
726.259A7.008A7.019A2.215A384.7889.66%58020.844.25 °C0.995
12.023V4.994V3.290V4.956V429.1552.36 °C115.1V
830.089A8.016A8.032A2.422A439.6489.15%58020.845.05 °C0.996
12.006V4.990V3.287V4.950V493.1553.75 °C115.1V
934.382A8.520A8.555A2.422A494.7588.65%63523.146.70 °C0.996
11.988V4.988V3.284V4.948V558.0955.85 °C115.1V
1038.425A9.036A9.054A3.041A549.6888.00%81527.647.27 °C0.996
11.970V4.984V3.280V4.931V624.6256.78 °C115.1V
1143.079A9.042A9.063A3.041A604.6087.39%97532.347.89 °C0.996
11.952V4.980V3.277V4.928V691.8557.80 °C115.1V
CL10.102A16.023A16.005A0.004A134.0682.80%58020.847.72 °C0.985
12.088V4.998V3.294V5.052V161.9055.62 °C115.1V
CL245.782A1.003A1.003A1.002A561.1288.64%84028.248.30 °C0.996
11.966V4.993V3.290V4.971V633.0558.27 °C115.1V

Load regulation at +12V isn't super tight, but it's pretty good on the other rails. On top of that, the RM550x has one of the steadiest 5VSB rails we've ever measured in a PSU around this capacity point. As you can see in the table, this PSU satisfies the 80 PLUS Gold requirements with flying colors, despite our test environment's very high ambient temperatures. This is definitely an efficient unit that will help you save some money on electricity over time.

The fan doesn't spin up to the 50% load test, and its speed is low once the control circuit engages it. Our equipment only registered more than 30 dB(A) once, and that was during the overload test with an ~48 °C ambient. To call the RM550x quiet is underselling it.

Contributing Editor

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

  • Dark Lord of Tech
    I just wish they would get the price down , these are a great lineup \ RX.
  • basroil
    From the performance it seems like CWT is finally something to consider... It's showing Leadex Gold/Seasonic levels of performance.
  • Dark Lord of Tech
    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.
  • William Henrickson
    They were on sale when new. I snagged an RM750i for $105 -w- shipping
  • Dark Lord of Tech
    Yeah the 550w should be about 79.99 to 89.99 , no rebates.
    Then I would grab a few.
  • JQB45
    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

    $89.99 for the 650W version.


    Sorry thats with mail in rebates...
  • Dark Lord of Tech
    I don't do rebates , takes to long , and maybe you get it maybe you don't , I'll wait for a newegg drop.
  • 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.
  • 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.
  • turkey3_scratch
    17653281 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.