Review Index:

Seasonic PRIME 600W Titanium Fanless Power Supply

Author: Lee Garbutt
Manufacturer: Seasonic

Specifications and Packaging


The Seasonic PRIME Titanium Fanless power supply is rated for a combined, continuous output power of up to 600 watts at up to 50°C (de-rated to 80% (480W) when temperature goes above 40°C). The PSU incorporates a single +12V rail that can deliver up to 50A (600W).  The PSU includes universal AC line input that automatically adjusts the AC line voltage (110-240 VAC) and active PFC, which makes the unit more environmentally friendly to the local power grid.

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Seasonic PRIME 600W Titanium Fanless PSU Specifications:

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(Courtesy of Seasonic)

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Packaging and Parts

The Seasonic Fanless power supply arrived packed inside a standard retail box showcasing the unit’s features and specifications.  

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In addition to the power supply, the box contains a power cord, mounting screws, a User Manual, case badge, wire ties, cable ties, and a large bundle of modular cables. All of the modular cables are the flat ribbon-style except for the 24-pin ATX cable that is nicely sleeved.

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(2) 4+4 pin CPU, (1) 24-pin ATX, and (2) PCI-E modular cables

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(3) SATA, (2) 4-pin Molex peripheral cables, and (1) 4-pin FDD adapter

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March 2, 2018 | 05:23 PM - Posted by Photonboy

In what world is this F*****G power supply going to stay below 40degC to keep from dropping down to 480W?

It will also dissipate much MORE HEAT into the main case anyway thus the other parts will have fans spin up more so it may be louder anyway.

I doubt you'd make a completely FANLESS system either (I know they recommend against that) since if you needed that much power and had no fans I doubt you'd keep the temperature below 40degC (especially in warmer areas).

Maybe I'm just stupid, but can anyone explain who might use this besides someone with relatively LOW POWER draw who wants a really quiet system (for which their already are PSU's that turn OFF their fans anyway)?

March 2, 2018 | 09:41 PM - Posted by Cyclops

At over 91% efficiency, only 9% of electricity is converted into heat, which in the case of this power supply, is 54 watts at 100% load. It's negligible.

I use a Fanless SeaSonic SS-520FL2 in my system paired with an overclocked 1080 Ti. It's a flawless operation. The system is liquid cooled with fans set to barely audible levels, so even under load, you can't hear anything.

March 4, 2018 | 04:07 AM - Posted by AnonymousLocust (not verified)

Your math is backwards, although your error in this case is rather insignificant.

The 91% are what the power supply delivers. 100% is what it draws from mains. In a simplified scenario, if the PSU delivers 600 W with a 91% efficiency, then it draws around 659 W from the mains (659 * 91% = 600). Thus, the loss is not 54 W but 59 W.

March 5, 2018 | 09:29 AM - Posted by Particle (not verified)

To add to your point for his/her benefit:

A simple shorthand for figuring out this sort of problem is to take the power out and not do any sort of multiply but rather perform a divide. Power out divided by efficiency equals power in. Power in minus power out equals power lost in conversion.

600 watts out / 0.91 efficient = 659 watts in

659 watts in - 600 watts out = 59 watts lost in conversion

March 3, 2018 | 01:14 PM - Posted by M (not verified)

You can always mount the PSU _outside_ the case (if the case allows of course)

Done it once at a system with dual Nocona Xeon's.. That was the only option to lower overall fan noise..

Unfortunately back then the max fanless PSU you could find was topping at 300W..

March 4, 2018 | 04:00 AM - Posted by John H (not verified)

Blower style GPU is probably what this is intended for.

March 2, 2018 | 09:42 PM - Posted by Cyclops

80+ Silver is a rating which no one seem to aim for anymore. You can find numerous power supplies rated for everything under the sun but not 80+ Silver. I wonder why that is.

March 5, 2018 | 08:59 AM - Posted by Jabbadap

Well many Dells, HPs and other PCs are usually been with 80plus silver PSU(With OEMs like Lite ONs, FSPs, Deltas). But now-a-days those too have been moving to gold rated ones...

I actually don't remember seeing silver rated psus on normal retail sale.

March 3, 2018 | 07:29 AM - Posted by VintageDude (not verified)

Sort of agree, any power supply of this size should come with a fan. You decide to run it at the speed, sound of your desire. Heat rises.

March 5, 2018 | 02:45 PM - Posted by Power (not verified)

Couple of fan headers would be nice.

March 8, 2018 | 07:57 PM - Posted by Photonboy

40degC vs 9% heat dissipation.

First off, HEAT and TEMPERATURE are certainly related but it's the DENSITY of heat that matters most, especially if a temperature sensor is near components in the PSU that get hotter than the average temperature of that PSU.

Remember that the INTERNAL case temperature can get pretty high, though of course it's much lower at the bottom. However, I have a sensor at the BOTTOM of my motherboard hitting roughly 50degC when gaming (i7 + GTX1080, 3xNoctua case fans at 700RPM).

So how hot is this PSU getting in a typical case at say 500W PSU load? (the spikes you should care about)

So adding 50W or so of heat raises the temperature above whatever it would normally be just sitting at that point in the case. If you're at 35degC then maybe that's enough to hit 40degC.

*As a solid product it may make sense as a long-term investment, but I'd like more numbers on how close to the 40degC cut-off it's getting to based on (at 500W+ power draw):
a) ambient room temperature, and
b) case cooling

In the SUMMER if I hit 30degC for example would I drop down to 480W power load in a particular system?

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