Corsair SF450 PSU Review

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Efficiency, Temperature And Noise


Our efficiency testing procedure is detailed here.

Using results from the previous page, we plotted a chart showing the efficiency of Corsair's SF450 at low loads, and loads from 10 to 110 percent of the PSU's maximum-rated capacity.

The SF450 is highly efficient under light and normal loads. Only the Cooler Master V450S manages to beat it. That unit is semi-modular though, and it's a lot larger than the SF450. The comparison isn't quite fair.

Efficiency At Low Loads

In the following tests, we measure the efficiency of Corsair's SF450 at loads significantly lower than 10 percent of the device's 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.

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Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)Fan NoisePF/AC Volts
11.209A0.491A0.477A0.195A19.6170.74%00 dB(A)0.926
22.447A0.989A0.985A0.396A39.7880.76%00 dB(A)0.964
33.685A1.486A1.494A5.036A59.8384.29%100019.9 dB(A)0.975
44.913A1.995A1.975A0.794A79.8286.70%100019.9 dB(A)0.978

Under light loads, efficiency is very high. The PSU even operates passively in the first two tests, generating zero noise. During the next tests, the fan noise is inaudible at 19.9 dB(A).

5VSB Efficiency

The ATX specification states that 5VSB standby supply efficiency should be as high as possible, recommending 50 percent or higher efficiency 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. 

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Test #5VSBDC/AC (Watts)EfficiencyPF/AC Volts

The 5VSB rail is highly efficient. Only FSP's HGX450 registers higher efficiency on this rail. Then again, that's an ATX PSU, not an SFX one.

Power Consumption In Idle And Standby

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Mode12V5V3.3V5VSBWattsPF/AC Volts

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).

Phantom power is really low, especially with 230V input.

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 45 °C (113 °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 of 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 45 °C (113 °F) ambient temperature. 

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

Under normal operating conditions the SF450 is a very quiet PSU. That's amazing given its ultra-compact dimensions that lead to a densely-populated PCB with restricted airflow between components. Apparently, high efficiency, minimal thermal output and a semi-passive mode combine to deliver near-silence, especially in ambient environments under 30 °C.

Contributing Editor

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

  • joz
    "No berg connector," is a con? And this is why Johnnyguru is the better website.
  • spdragoo
    Interesting...a small-factor PSU with enough power & PCIe connectors for those with a prebuilt system that want to upgrade their GPUs without having to rebuild the entire system from scratch.
  • turkey3_scratch
    17801331 said:
    "No berg connector," is a con? And this is why Johnnyguru is the better website.

    I find it hard to believe you actually read power supply reviews, because on Jonnyguru OklahomaWolf always scores against having a berg connector. Also, Jonnyguru only tests a few things compared to Aris's reviews on Tomshardware and Techpowerup.

    Edit: I just realize I misinterpreted what you said. I do apologize, it was my mistake. I did not realize the word "not". Yes, Aris and Jonnyguru have different reviews on berg connectors. I still don't think that just because a berg connector is a good thing means that Jonnyguru is a better review site. That seems to be an extremely minor detail to judge one whole review site to this one.
  • Onus
    Hmmm, looks like the only thing not to like is that all the SATA connectors are on one cable, which could be a problem even in some small cases where this would be used; the optical drive might not be near the other drives.
  • jimmysmitty
    17801372 said:
    Hmmm, looks like the only thing not to like is that all the SATA connectors are on one cable, which could be a problem even in some small cases where this would be used; the optical drive might not be near the other drives.

    And that is easy to solve since you will probably be able to buy cables and change the molex out for another SATA cable, like all Corsair PSUs.

    I wish this was out when I rebuilt my HTPC. Would have preferred it since what was available at the time was just meh and nowhere near the performance.
  • turkey3_scratch
    Just finished review. Great unit, wonderful. I'd take this over one of the Silverstones any day.
  • Aris_Mp
    "No berg connector," is a con? And this is why Johnnyguru is the better website.

    Some components still need a berg connector ( e.g. sound card panels, fan controllers, etc.) And it costs almost nothing to add a berg adapter into the bundle.
  • JQB45
    Exciting to see more SFF power supplies of good quality. Now I have even less reason not to buy a mini-itx case next time.
  • turkey3_scratch
    17801331 said:
    "No berg connector," is a con? And this is why Johnnyguru is the better website.

    On second read of your post, I misinterpreted what you said, and I do apologize. I thought you were upset that including a berg connector was a con, I'm sorry I misinterpreted it. Yeah, this unit doesn't have a berg connector. Here's the thing: you have OklahomaWolf who scores against having berg connectors, and you have Aris who likes to see berg connectors. Two complete opposite subjective standpoints. What I don't understand is how this makes Jonnyguru a better site.

    Whenever I read power supply reviews, I always ignore the conclusion page. I usually don't read it. The information is all there for you to judge. Whether or not the author thinks a berg connector is good or bad is an opinion, but it does not detract from how professional Aris's reviews are. I mean, come on, Jonnyguru does not test transient response, hold-up time, AC_LOSS to PWR_OK, 1500 crossload possibilities, extensive efficiency and fan RPM, etc. tests. I just can't see how Jonnyguru can be a better review site because they only do a fractional amount of testing.

    Jonnyguru's resources are limited, so it's understandable. I think some people like Jonnyguru just because of how "fast" one can fly through the reviews. It takes me a solid 25 minutes of thorough analysis to read Aris's reviews, I can go through a Jonnyguru one in under 10 minutes. There is just so much information here, so why is it you think Jonnyguru is a better site?
  • AlistairAB
    Thank you Tom's Hardware for highlighting the lack of the SFX adapter bracket. It can be purchased directly from Corsair at the following link:

    This was also mentioned in a review, and received many down votes. Perhaps this is because of American focused reviews, so most people think it is not a big deal to order a $5.99 adapter directly from Corsair or through a 3rd party.

    However this is actually a serious mistake, as ordering this to Canada from Corsair requires over $50 USD in shipping. Total cost for the bracket after shipping and taxes is over $80 CAD which is absolutely ridiculous for a part with no retail availability or alternatives that should have been included in the box.

    I talked with Corsair support this morning and opened a ticket, and they provided exemplary customer service and have now promised to send the adapter to me in Canada for free. Perhaps this will work for some of you having the same problem.

    There are many small form factor cases that accept ATX PSUs that need this bracket (Silverstone and Lian Li cases), where the short cable lengths don't pose a problem.