The Seasonic Focus Plus Gold 750FX 750W PSU Review: SeaSonic Quality at Mainstream Prices

Hot Test Results

The following tables showcase the power quality figures of the SeaSonic Focus Plus Gold 750FX, which generally are very good. The maximum voltage ripple on the 12V line is 30 mV, which is admittedly an unimpressive figure when compared to higher tier modern products, yet it's undoubtfully excellent for a mid-tier product as it's merely 25% of the ATX design guide's recommended 120 mV limit. The filtration of the 3.3V and 5V lines is equally good, with our instruments reading a maximum voltage ripple of 16 mV on the 5V line. Voltage regulation is at about 1% for all three voltage lines, an excellent figure for a product of this class.

The energy conversion efficiency of the SeaSonic Focus Plus Gold 750FX barely even drops when the unit is operating inside our hotbox, indicating excellent resistance to thermal stress. The degradation increases when the load is greater than 600 Watts, suggesting that the components of the PSU are facing some thermal stress, as expected under such high ambient temperatures after reviewing the specifications of the unit. The average efficiency reduction is only 0.5%, with the worst figures being 0.8-0.9% when the load is greater than 600 Watts.

Unlike before, the cooling fan of the SeaSonic Focus Plus Gold 750FX PSU started immediately after we powered on the PSU into our hotbox. Even at the lowest of loads, the fan is now both spinning and audible, with its speed increasing as the load increases. The speed of the fan peaks when the load reaches 600 Watts, maintaining barely operational temperatures under such adverse operating conditions.