Corsair SF450 Platinum SFX PSU Review: Best of the Best

Transient Response Tests

Advanced Transient Response Tests

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

Ιn these tests, we monitor the PSU's response in several scenarios. First, a transient load (10A at +12V, 5A at 5V, 5A at 3.3V, and 0.5A at 5VSB) is applied for 200ms as the PSU works at 20 percent load. In the second scenario, it's hit by the same transient load while operating at 50 percent load.

In the next sets of tests, we increase the transient load on the major rails with a new configuration: 15A at +12V, 6A at 5V, 6A at 3.3V, and 0.5A at 5VSB. We also increase the load-changing repetition rate from 5 Hz (200ms) to 50 Hz (20ms). Again, this runs with the PSU operating at 20 and 50 percent load.

The last tests are even tougher. Although we keep the same loads, the load-changing repetition rate rises to 1 kHz (1ms).

In all of the tests, we use an 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 these "Advanced Transient Response Tests," and they are designed to be very tough to master, especially for a PSU with a capacity of less than 500W.  

We should note that the ATX spec requires for capacitive loading during the transient rests, but in our methodology we chose to apply the worst case scenario with no extra capacitance on the rails. 

Advanced Transient Response at 20 Percent – 200ms

VoltageBeforeAfterChangePass/Fail
12V12.083V11.826V2.13%Pass
5V5.050V4.949V2.00%Pass
3.3V3.349V3.260V2.66%Pass
5VSB5.020V4.968V1.04%Pass

Advanced Transient Response at 20 Percent – 20ms

VoltageBeforeAfterChangePass/Fail
12V12.073V11.756V2.63%Pass
5V5.049V4.930V2.36%Pass
3.3V3.348V3.245V3.08%Pass
5VSB5.021V4.962V1.18%Pass

Advanced Transient Response at 20 Percent – 1ms

VoltageBeforeAfterChangePass/Fail
12V12.072V11.723V2.89%Pass
5V5.049V4.935V2.26%Pass
3.3V3.348V3.245V3.08%Pass
5VSB5.021V4.979V0.84%Pass

Advanced Transient Response at 50 Percent – 200ms

VoltageBeforeAfterChangePass/Fail
12V12.067V11.816V2.08%Pass
5V5.047V4.940V2.12%Pass
3.3V3.345V3.251V2.81%Pass
5VSB5.005V4.947V1.16%Pass

Advanced Transient Response at 50 Percent – 20ms

VoltageBeforeAfterChangePass/Fail
12V12.062V11.762V2.49%Pass
5V5.046V4.924V2.42%Pass
3.3V3.344V3.235V3.26%Pass
5VSB5.006V4.951V1.10%Pass

Advanced Transient Response at 50 Percent – 1ms

VoltageBeforeAfterChangePass/Fail
12V12.062V11.771V2.41%Pass
5V5.046V4.918V2.54%Pass
3.3V3.344V3.241V3.08%Pass
5VSB5.006V4.955V1.02%Pass

Transient response on the +12V rail doesn't look good. Because this is a low-capacity PSU, it takes quite a hit from the loads that we apply. Performance is much better on the minor rails (especially 3.3V). But the 80 PLUS Gold-rated SF450 posts better benchmark results overall.

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

Transient Response At 20 Percent Load – 200ms

Transient Response At 20 Percent Load – 20ms

Transient Response At 20 Percent Load – 1ms

Transient Response At 50 Percent Load – 200ms

Transient Response At 50 Percent Load – 20ms

Transient Response At 50 Percent Load – 1ms

Turn-On Transient Tests

In the next set of tests, we measure the SF450’s response in simpler transient load scenarios—during its power-on phase.

For our first measurement, we turn the power supply off, dial in the maximum current the 5VSB rail can handle, and switch the PSU back on. In the second test, we set the +12V rail's maximum load and start the PSU while it is in standby mode. In the last test, with the PSU switched completely off, we dial in the +12V rail's maximum load before 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).

All three tests look almost performance; we don't spot any notable voltage overshoots or spikes.

MORE: Best Power Supplies

MORE: How We Test Power Supplies

MORE: All Power Supply Content

Create a new thread in the Reviews comments forum about this subject
4 comments
Comment from the forums
    Your comment
  • SR-71 Blackbird
    I run a SF600 Gold in one of my setups. To improve on that is awesome. Thanks for the review Aris!
  • Brian_R170
    Nice to see more quality PSUs available for small form-factor cases. The included ATX-to-SFX adapter is welcome addition, but I prefer the flat non-sleeved cables found on the SF450 Gold in small cases where space to bundle cables is limited.
  • TripleHeinz
    I've been running for 3 years in a row, almost every single day with the PC on, a FSP FSP300-60GHS-R SFX PSU in my custom-made mini ITX system. It is rated at 300W, 80 plus, 80mm fan with sensor, completely silent, comes with an ATX bracket+cable+screws, user manual plus nice box, a total marvell. I think it is a very respectable PSU (good internals) if you ignore the standard satin gray color.

    Well I'm here to say that the Corsair SFX PSU is very impressive but for that price you'll have to justify the buy with a very specific purpose of your own. I can only recommend the FSP SFX PSU, the 300W model (the 450W model is said to be loud), it is more than enough for HTPC and low power ITX parts (and midrange hardware as well: I5 + GTX1060).

    Disclaimer: I do not work for FSP ;p
  • jayjr1105
    Great review. Amazing these SFX's getting so good even with less room.

    May I suggest the latest Rosewill Capstone M lineup by Andyson for a future review. The previous Superflower and Enhance units were well reviewed but they switched to the Andyson GX platform. Thanks!