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Seasonic X-Series 650W KM3 Power Supply Review

The Seasonic X-Series 650W KM3 is nicely finished with thick paint resistant against rough handling. As with the 850W KM3, the unit passed our screwdriver stress test – we run the head down the side of the chassis with a little force. It didn’t mark.

The unit measures 160mm x 150mm x 86 mm (LxWxH). It will fit into any mainstream ATX compliant chassis.

The large fan is hidden behind a black honeycomb grill. We will look at the fan in more detail when we crack open the chassis later in the review.

One side of the power supply is vented which helps enhance air flow. There is also a power switch and connector at the side. The Seasonic badge is seen underneath the power port/switch.

The KM3 modular panel has changed completely over the last revision. There is now a ‘hybrid’ fan switch which you can toggle on or off – the blue sticker alerts you to this initially and should be removed before using the supply. Seasonic have said this is the industries first ‘advanced three phased thermal control’.

The Hybrid Silent Fan Control provides three operational stages:  Fanless, Silent, and Cooling Mode. In addition, there is a switch provided to allow for manual selection between the Seasonic S2FC (fan control without Fanless Mode) and the S3FC (fan control including Fanless Mode).

Seasonic X-Series 650W Power Supply (KM3)
DC Output
Max Output
Total Power 125W 648W 6W 15W

54A can be delivered to the +12V rail, which is plenty for two relatively high end graphics cards.

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  • Black Mamba

    Excellent, as we would expect by now !

  • harris

    My only problem with Seasonic is the pricing, they may be great, but I can’t afford the products of theirs I want to buy, I have to get cheaper.

  • Alex

    I have their last 650W PSU and I am happy with it. I always thought ribbon cabling was worse than the fat sleeved cabling, but I was clearly wrong.

  • Stevie

    Great company, always buy their products, and they last many many years, never had a seasonic fail. wise to see corsair and other companies using their designs.

  • Ivan

    Just ordered one as I needed a new 650w, my thermaltake 750w died and it was noisy too.

    THanks for review

  • Darth Digglers

    Bah! Newegg dont list these as KM2 or KM3, what a mess. they needed to change the name to R2 or something so retailers would list them properly. they are all falling under the X series name, which is a mess.

  • djoCC22

    i 1 it!!! great product but not great price for me.. i need titanium cert…..