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Corsair RM550x Power Supply Review

The lowest-capacity unit Corsair's RMx line outputs up to 550W and is 80 PLUS Gold-certified. It features fully modular cabling, offers great performance and is nearly silent throughout its operating range, too.

Transient Response Tests

Advanced Transient Response Tests

For details on our transient response testing, please click here.

In these tests, we monitor the response of the PSU in two different scenarios. First, a transient load (10A at +12V, 5A at 5V, 5A at 3.3V and 0.5A at 5VSB) is applied for 200ms while the PSU works at 20 percent load. In the second scenario, the PSU is hit by the same transient load while operating at 50 percent load. In both tests, we use our oscilloscope to measure the voltage drops caused by the transient load. The voltages should remain within the ATX specification's regulation limits.

These tests are crucial because they simulate the transient loads a PSU is likely to handle (such as booting a RAID array or an instant 100 percent load of CPU/GPUs). We call them "Advanced Transient Response Tests," and they are designed to be very tough to master, especially for PSUs with less than 500W capacity.

Advanced Transient Response at 20 Percent

VoltageBeforeAfterChangePass/Fail
12V12.098V12.022V0.63%Pass
5V5.013V4.956V1.14%Pass
3.3V3.309V3.237V2.18%Pass
5VSB4.990V4.945V0.90%Pass

Advanced Transient Response at 50 Percent

VoltageBeforeAfterChangePass/Fail
12V12.050V11.975V0.62%Pass
5V5.003V4.948V1.10%Pass
3.3V3.299V3.225V2.24%Pass
5VSB4.971V4.925V0.93%Pass
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The +12V rail's deviation is very small; the same goes for the other rails as well. In general, Corsair's RM550x registers very good performance.

Here are the oscilloscope screenshots we took during Advanced Transient Response Testing:

Transient Response At 20 Percent Load

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Transient Response At 50 Percent Load

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Turn-On Transient Tests

In the next set of tests, we measure the PSU's response in simpler transient load scenarios—during its power-on phase.

For the first measurement, we turn off the PSU, dial in the maximum current the 5VSB can output and switch on the PSU. In the second test, we dial the maximum load the +12V can handle and start the PSU while it's in standby mode. In the last test, while the PSU is completely switched off (we cut off the power or switch off the PSU by flipping its on/off switch), we dial the maximum load the +12V rail can handle before switching on the PSU from the loader and restoring power. The ATX specification states that recorded spikes on all rails should not exceed 10 percent of their nominal values (+10 percent for 12V is 13.2V, and 5.5V for 5V).

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There is a tiny spike at 5VSB, which is nothing to worry about. There are no spikes or voltage overshoots in the second test, but the rail takes a while before it reaches its nominal voltage. In the third and last test, there are some small jaws on the waveform. These aren't significant, though. Overall, the measured performance is good.

  • Dark Lord of Tech
    I just wish they would get the price down , these are a great lineup \ RX.
    Reply
  • basroil
    From the performance it seems like CWT is finally something to consider... It's showing Leadex Gold/Seasonic levels of performance.
    Reply
  • 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.
    Reply
  • William Henrickson
    They were on sale when new. I snagged an RM750i for $105 -w- shipping
    Reply
  • Dark Lord of Tech
    Yeah the 550w should be about 79.99 to 89.99 , no rebates.
    Then I would grab a few.
    Reply
  • 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
    http://pcpartpicker.com/part/corsair-power-supply-cp9020090na
    $79.99

    $89.99 for the 650W version.

    UPDATE:

    Sorry thats with mail in rebates...
    Reply
  • 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.
    Reply
  • 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.
    Reply
  • 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.
    Reply
  • 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.
    Reply