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. 

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Primary Rails And 5VSB Load Regulation

Load Regulation testing is detailed here.

  • Result 1 -9_Load_Regulation_12V_Comparison
  • Result 2 -13_Load_Regulation_12V_Graph
  • Result 3 -10_Load_Regulation_5V_Comparison
  • Result 4 -14_Load_Regulation_5V_Graph
  • Result 5 -11_Load_Regulation_33V_Comparison
  • Result 6 -15_Load_Regulation_33V_Graph
  • Result 7 -12_Load_Regulation_5VSB_Comparison
  • Result 8 -16_Load_Regulation_5VSB_Graph

Hold-Up Time

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

  • hold_up_time
  • AC_loss_to_PWR_OK_hold_up_time
  • PWR_OK_inactive_to_DC_loss_delay
  • Result 9 - 28_Hold-Up_Time_All
  • Result 10 - 29_Hold-Up_Time_Comparison
  • Result 11 - 30_AC_Loss_to_PWR_OK_Hold_Up_Time
  • Result 12 - 31_PWR_OK_Inactive_to_DC_Loss_Delay

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.

  • Result 13 -26_Inrush_Current_115V-230V.png
  • Result 14 -27_Inrush_Current_Comparison_230V

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.

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%580 20.847.72 °C0.985
12.088V4.998V3.294V5.052V161.9055.62 °C115.1V
CL245.782A1.003A1.003A1.002A561.1288.64%840 28.248.30 °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.

Corsair RM550x
$78.99Newegg

Previous Next
Summary
  1. Introduction
  2. Packaging, Contents, Exterior And Cabling
  3. A Look Inside And Component Analysis
  4. Load Regulation, Hold-Up Time And Inrush Current
  5. Efficiency, Temperature And Noise
  6. Cross-Load Tests And Infrared Images
  7. Transient Response Tests
  8. Ripple Measurements
  9. Performance, Performance Per Dollar, Noise and Efficiency Ratings
  10. Pros, Cons And Final Verdict
About the author
Aris Mpitziopoulos

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

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36 comments
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    Your comment
  • 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
    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...
  • 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
    205977 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.
  • 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.
  • 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.
  • 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
  • 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.
  • 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 )
  • 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.
  • 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.
  • 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.
  • turkey3_scratch
    2077519 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?
  • 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 )
  • turkey3_scratch
    That is the Superflower Leadex 550W where the Pwr_OK signal drops after the voltage is below 10.8V, and while the EVGA 550 G2 is based off that unit, Aris does not mention that same behavior for the G2 on the 550 G2 review. So it is possible the 550 G2 does not have this same mistake, but I am unsure myself. They could have made modifications.

    Edit: Ahh, he didn't check AC loss to PWR_OK in the G2 review, so the behavior is most likely still present.
  • turkey3_scratch
    This behavior is also present on Sirfa-made units, which have very high AC loss to PWR_OK off hold up times because their PWR_OK signal does not turn off until the voltage is somewhere below like 10.2V! http://www.jonnyguru.com/forums/showthread.php?t=12886

    The real question though is how fatal, in terms of the 550 G2, this really is. Is the 10.8V+ applied to the unit's VRM components for 12ms really going to harm the unit fatally? If anything, those Sirfa units are more dangerous. A higher AC loss to PWR_OK loss time is not necessarily good if the voltage is too low. They should be setting the threshold to 11.4V, not these lower values, so shame on Superflower and Sirfa for this. But it's actually a good thing the 550 G2 is only 12ms, you don't want those low voltages to be handled by the 12V VRM components for any longer, shorter is better in this case. But yes you are correct, they should improve these, but again does this merit the $20 extra for the 550 RMx? I'd have to ask a PSU expert how much of a harm this 10.8V+ for 12ms will make, as I'm not an expert on that.
  • Aris_Mp
    hold-up time tests are not the easiest thing to do since besides extra equipment you also need GOOD knowledge of what you are doing. On top of that in order to measure hold-up time along with power good time and other stuff as well you need an accurate (thus expensive) four channel, at least, scope. Till I raised enough money to buy one I didn't have the capability to measure both hold-up times so I provided only the power good signal's time.

    If your PSU has a really short hold-up time in some cases your UPS won't be able to handle the job, especially if its transfer time is higher than 15-20ms. Moreover the longer the PSU goes without power, the larger the in-rush current it will draw when it has power again. This means that its bulk caps will be almost empty so the In-rush current could exceed the current handling capacity of the UPS and cause its shut down. This means that a PSU's hold-up time IS important!
  • turkey3_scratch
    Aris, you say the in-rush current could exceed the current handling of the UPS, don't you mean the PSU? And are you the Aris who wrote the article? Also, if the in-rush current exceeds the current handling capacitor of the bulk caps and the unit shuts down, will that cause hardware damage at all?
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