Efficiency, Differential Temperature and Noise
Efficiency
Efficiency is defined by the power output divided by the power input and is usually expressed as a percentage. If a PSU were a 100% efficient (which none are) 600 watts of AC power going in would result in 600 watts of DC power coming out (with no waste heat to dissipate). In the real world there are always inefficiencies and power is lost in the form of heat during the conversion process. Newer revisions to the ATX12V Power Supply Design Guide V 2.2 have continued to increase the efficiency recommendations for PC switching mode power supplies and now lists both required and recommended minimum efficiencies.
We measured the AC power input to the PRIME 600W Fanless PSU with an Extech power analyzer while the total DC load was found by adding all the individual +3.3V, +5V, +12V, -12V and +5VSB loads together.
The overall efficiency of the power supply was again excellent and easily meets the rigorous standards for 80 Plus Titanium certification.
80 Plus Program
Note: Tests conducted at room temperature (25°C)
Differential Temperature and Noise Levels
We tested the PRIME 600W Fanless power supply on an open bench, not inside an enclosure. Thermocouples were placed above (T out) and beside (T in) the PSU. The ambient room air temperature was 23ºC (74ºF) +/- 0.5ºC during testing.
T out = temperature of air above the top of the power supply
T in = temperature of room air
Delta T = T out – T in
The PSU was silent with no indication of audible coil whine. I could actually feel the warm air flowing out the top of the power supply (via natural convection) at 100% load. Because this is a fanless PSU, it needs to be installed in a case with very good airflow.
????
In what world is this
????
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)?
At over 91% efficiency, only
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.
Your math is backwards,
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.
To add to your point for
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
You can always mount the PSU
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..
Blower style GPU is probably
Blower style GPU is probably what this is intended for.
80+ Silver is a rating which
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.
Well many Dells, HPs and
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.
Sort of agree, any power
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.
Couple of fan headers would
Couple of fan headers would be nice.
40degC vs 9% heat
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?