Cold Test Results 

For our PSU testing, we are using various high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M 40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox and various other bits and parts. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs - 2014 Pipeline post.

The efficiency of the SeaSonic Focus Gold SGX-650 SFX PSU is very good. Although the unit technically fails to meet the 80Plus Gold certification requirement for 90% efficiency at a 20% load when powered from a 230V AC source, it showcased exceptional efficiency across the entire load range. Conversely however, the efficiency drop when the unit is powered from a 115V AC source is very small, from practically zero at low loads up to a maximum of about 0.75%. This allows the unit to easily surpass the 80Plus Gold requirements for an input voltage of 115V AC.

SeaSonic designed the thermal control of the Focus Gold SGX-650 to utilize a semi-fanless mode, meaning that the fan will start only after the load is greater than about 180 Watts or when it is absolutely necessary. As expected, the internal temperatures of the PSU rise sharply under low loads due to the lack of active cooling, but they quickly stabilize once the fan starts. Considering the size and compactness of the design, the internal temperatures of the Focus Gold SGX-650 are quite low.

Despite the use of a low-profile 120 mm fan, it seems that the cooling requirements of the Focus Gold SGX-650 are low. Even when the fan does start, it barely reaches audible levels even when the PSU is heavily loaded. Assuming that it takes a rather powerful system to heavily load a 650 Watt PSU, it is very likely that any sound coming from the PSU will be masked by the noise of other components.

The SeaSonic Focus Gold SGX-650 SFX PSU Hot Test Results (~45°C Ambient Temperature)
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  • u.of.ipod - Thursday, March 7, 2019 - link

    This review needs to be updated to state this unit is SFX-L, not SFX. This unit will not fit in a lot of small form factor (SFF) cases that only accept SFX sized PSU, not the extra long SFX-L.
  • johnnycanadian - Thursday, March 7, 2019 - link

    I don't think this one is SFX-L: this one is 100mm deep whereas SFX-L PSUs are 130mm deep. This one seems to be SFX through-and-through.
  • NateDawg72 - Thursday, March 7, 2019 - link

    It is definitely not 100mm, as stated at the top of the second page of the review and in Seasonic's specifications. It is 125mm deep
  • johnnycanadian - Thursday, March 7, 2019 - link

    My apologies! Yup, I see the extra 25mm in the specs; I misread the original. Bloody hell, this would have been a decent choice to drop into my 2400G-in-an-Apple-][-case project. Thanks for the keen eye!
  • Spoelie - Friday, March 8, 2019 - link

    Use the corsair SF450 or 650 instead in that case
  • Samus - Monday, March 11, 2019 - link

    I guess the real catch is this effectively becomes SFX-L after connecting the cables because the connectors and wires add about 20mm to the length, where a non modular design could have the wires sandwiched between an interfering component.
  • dromoxen - Thursday, March 21, 2019 - link

    Yep thats wht I was thinking , if you include the bulky connectors , thats maybe why modular FSX PSU should have some sort of flat connectors or have them indented (somehow).
    Johhny Canadian ..650w , even 450w is too much for a 2400G , You'd get away with 250w or even HDPLEX 160w, surely..and unless you plan to light it up like leicester Square.?
  • dromoxen - Thursday, March 21, 2019 - link

    And that lowered rating vs the op, temp is a bit sneaky ...
  • nevcairiel - Thursday, March 7, 2019 - link

    The first paragraph on the second page specifically calls out that its longer then normal SFX and therefor may not fit in some cases, FWIW.
  • Death666Angel - Thursday, March 7, 2019 - link

    Yeah, but there is a name for them and that is SFX-L as u.of.ipod stated. Makes it much less ambiguous.

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