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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.

Corsair RM550x

EVGA SuperNOVA 550 G2

EVGA SuperNOVA 550 GS

Primary Rails And 5VSB Load Regulation

Load Regulation testing is detailed here.

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Hold-Up Time

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

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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.

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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 #	12V	5V	3.3V	5VSB	DC/AC (Watts)	Efficiency	Fan Speed (RPM)	Noise (dB[A])	Temps (In/Out)	PF/AC Volts
1	2.739A	1.994A	1.990A	1.001A	54.77	83.99%	0	0	48.04 °C	0.944
1	12.114V	5.017V	3.312V	4.993V	65.21	83.99%	0	0	39.55 °C	115.1V
2	6.522A	2.990A	2.990A	1.200A	109.78	88.58%	0	0	48.85 °C	0.978
2	12.100V	5.013V	3.308V	4.988V	123.94	88.58%	0	0	40.18 °C	115.1V
3	10.658A	3.497A	3.507A	1.403A	164.90	90.01%	0	0	50.33 °C	0.987
3	12.085V	5.010V	3.305V	4.981V	183.20	90.01%	0	0	41.40 °C	115.1V
4	14.798A	3.994A	3.997A	1.605A	219.80	90.56%	0	0	51.70 °C	0.993
4	12.071V	5.008V	3.300V	4.975V	242.71	90.56%	0	0	42.45 °C	115.1V
5	18.607A	4.988A	5.001A	1.810A	274.77	90.56%	0	0	52.98 °C	0.994
5	12.056V	5.004V	3.298V	4.969V	303.41	90.56%	0	0	43.73 °C	115.1V
6	22.423A	6.001A	6.010A	2.011A	329.75	90.14%	580	20.8	43.38 °C	0.995
6	12.040V	4.999V	3.294V	4.964V	365.81	90.14%	580	20.8	51.16 °C	115.1V
7	26.259A	7.008A	7.019A	2.215A	384.78	89.66%	580	20.8	44.25 °C	0.995
7	12.023V	4.994V	3.290V	4.956V	429.15	89.66%	580	20.8	52.36 °C	115.1V
8	30.089A	8.016A	8.032A	2.422A	439.64	89.15%	580	20.8	45.05 °C	0.996
8	12.006V	4.990V	3.287V	4.950V	493.15	89.15%	580	20.8	53.75 °C	115.1V
9	34.382A	8.520A	8.555A	2.422A	494.75	88.65%	635	23.1	46.70 °C	0.996
9	11.988V	4.988V	3.284V	4.948V	558.09	88.65%	635	23.1	55.85 °C	115.1V
10	38.425A	9.036A	9.054A	3.041A	549.68	88.00%	815	27.6	47.27 °C	0.996
10	11.970V	4.984V	3.280V	4.931V	624.62	88.00%	815	27.6	56.78 °C	115.1V
11	43.079A	9.042A	9.063A	3.041A	604.60	87.39%	975	32.3	47.89 °C	0.996
11	11.952V	4.980V	3.277V	4.928V	691.85	87.39%	975	32.3	57.80 °C	115.1V
CL1	0.102A	16.023A	16.005A	0.004A	134.06	82.80%	580	20.8	47.72 °C	0.985
CL1	12.088V	4.998V	3.294V	5.052V	161.90	82.80%	580	20.8	55.62 °C	115.1V
CL2	45.782A	1.003A	1.003A	1.002A	561.12	88.64%	840	28.2	48.30 °C	0.996
CL2	11.966V	4.993V	3.290V	4.971V	633.05	88.64%	840	28.2	58.27 °C	115.1V

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.

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Aris Mpitziopoulos

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

36 Comments Comment from the forums

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

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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.