The Seasonic Focus SPX-750 (2021) is a 750W fully modular, SFX form factor power supply. It offers a single hybrid fan mode and is priced at a MSRP of $169.99 USD.
Its SFX form factor makes it an excellent choice for small form factor builds, though the included shorter cables may pose challenges in some setups. Additionally, it is an older model and not designed according to ATX 3.0 specifications.
Despite this, the Focus SPX-750 (2021) stands out for its included accessories, high efficiency at low wattages, and reliable load regulation, making it a recommendation for users seeking a power supply for smaller builds.
WHAT YOU NEED TO KNOW
THE GOOD
- Load Regulation
The power supply demonstrated excellent load regulation, with the 12V rail consistently maintaining a voltage above 12V.
- Form Factor
As an SFX form factor power supply, it is perfect for small form factor cases. It also includes an adapter bracket, making it compatible with all ATX-supported cases.
THE BAD
- Resiliency
It only sustained up to 11 ms and 10 ms at full rated load for 115V and 230V. This is shorter than desired and may not be as resilient to poor power quality.
THE REST
- Overall
This PSU did not excel in all tests, yet it did not fail any either. Apart from its load regulation and OCP, most results were average. It remains a recommended option for its high efficiency at low wattages and reliable load regulation.
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The Seasonic Focus SPX-750 (2021) is a SFX form factor power supply. In the Box, it comes with a range of accessories, including a PSU and cable bag, as well as velcro cable ties for added convenience.
The unit features flat, webbed cables that are moderately flexible, although their short length may present challenges when connecting components within a computer case. While shorter cables are ideal for organizing in small form factor cases, they may not reach all necessary connections in larger cases.
The power supply is equipped with a standard 92 mm fluid dynamic bearing fan, ensuring efficient cooling.
The power ratings and specifications align with expectations for this price range. On the Seasonic specifications webpage it specifies that the Operating Temperature is 0°C to 50°C, though we cannot verify this through testing.
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Front of the box.
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Power input side of the PSU.
Top of the PSU displaying the fan.
Bottom of the PSU displaying the specifications.
| +12 V | +5 V | +3.3 V | +5 Vsb | -12 V | |
|---|---|---|---|---|---|
| CURRENT | 62 A | 20 A | 20 A | 3 A | 0.3 A |
| WATTAGE | 744 W | 130 W | 15 W | 3.6 W | |
| 750 W | |||||
Please note that the above ratings are manufacturer advertised specifications.
The Focus SPX-750 (2021) includes a single hybrid fan mode, controlled by Seasonic’s “Smart and Silent Fan Control”. This system operates in three stages: Fanless Mode, Silent Mode, and Cooling Mode.
The power supply also comes with all standard protections and is backed by a 10-year warranty, as is typical for power supplies of this class.
In terms of performance, the Focus SPX-750 (2021) delivers average but not exceptional results. However, its load regulation is particularly good, with the 12V rail maintaining a stable with only a 0.094V drop across its full rated output power range of 750W. This performance is well within ATX specifications and consistent with other power supplies tested.
The power supply meets ATX ripple specifications, though the 12V rail displayed a slightly higher peak-to-peak signal ripple of 38 mV, while the 5V and 3.3V rails showed lower ripples of 21 mV and 22 mV, respectively.
Excursion tests are not mandatory for non-ATX 3.0 power supplies, and the Focus SPX-750 (2021) wasn't designed for these standards. However, we tested this power supply with reduced excursion percentages. These tests followed the same timing as the standard set but only went up to 150% of the rated load instead of 200%. The Focus SPX-750 (2021) did not pass the more demanding regular excursions.
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The Focus SPX-750 (2021) is 80PLUS Platinum certified, achieving 92% efficiency at 50% of its maximum rated load. However, it was 0.5% off from the 94% efficiency requirement for 50% load at 230V input.
The unit’s performance in brownout tests was below average, sustaining only up to an 11 ms and 10 ms dropout at full rated load for 115V and 230V, respectively. This shorter duration may make the power supply less resilient to brownouts.
All the protections triggered at approximately 140%, except for the 5Vsb and -12V OCP, where the 5Vsb OCP triggered at 150%, and the -12V hit the 300% limit. The Over Power Protection engaged at a maximum of 140% of the rated load, with the 12V rail alone capable of 87A, or 141% of its rating, ensuring safety against component faults and allowing for minor exceedances in power draw beyond the official rating.
