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) 850 watts of AC power going in would result in 850 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 ST85F-PT 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 SilverStone 850W Platinum Series power supply started out strong, easily exceeding 90% (at 20% load) and 92% efficiency requirements (at 50% load). The overall efficiency of the ST85F-PT power supply is excellent and meets the tough 80 Plus Platinum guidelines, even when operating on 120VAC and at elevated temperatures.
80 Plus Program
Note: Tests conducted at room temperature (25°C)
Differential Temperature and Noise Levels
To simulate a demanding environment, some of the warm exhaust air from the PSU under test is recirculated back to the intake through a passive air duct, which allows the PSU air inlet temperature to increase with load, up to 40°C.
The differential temperature across the power supply was calculated by subtracting the internal case air temperature (T in) from the temperature of the warm exhaust air flowing out the back of the power supply (T out).
Thermocouples were placed at the air inlet and exhaust outlet. The ambient room air temperature was 23ºC (74ºF) +/- 0.5ºC during testing.
T out = temperature of air exhausting from power supply
T in = temperature of air entering power supply
Delta T = T out – T in
Sound pressure level readings were taken 3’ away from the rear of the case in an otherwise quiet room. The ambient noise level was ~27 dBA.
*Fan not spinning
The ST85F-PT Platinum Series power supply starts out silent, in fanless mode. The fan started spinning as soon as we entered test #3 at the 50% load mark and stays quiet through mid-power range. At full load with an elevated ambient temperature, the cooling fan did speed up and the noise became noticeable but never really loud.
SilverStone ST85F-PT Platinum Series Fan Speed
(Courtesy of SilverStone)
Did SilverStone send you the
Did SilverStone send you the PSU for review, or did you request it? If the latter, I’d say you missed an opportunity by going for the highest capacity one of the lineup. The 550W is far more interesting, as it’s one of the lowest capacity Platinum units out there, and a perfect fit for today’s high end GPUs.
The 850W model was sent to us
The 850W model was sent to us for review as SilverStone wanted to showcase the highest power in the smallest package. However, we may follow up with a review of the 550W unit. Its always nice to have the opportunity to check out more than one unit in a new series.
That would be great, hope you
That would be great, hope you are able to get one in for review.
Of course I see SilverStone’s point (850W Platinum in a smaller package than most 5-600W units is not bad at all), but high powered PSUs are less and less relevant in today’s PC builds. 3,5″ HDDs are slowly dying, multi-GPU was never really a big thing, and is quickly falling to the wayside, and >95W CPUs with actual performance to match are reserved for those with too much money to spend (although Zen might change that).
SilverStone should be lauded as one of the first PSU makers to make <700W Platinum units, but we still had a long way to go. I'm still waiting for something compact, modular and high efficiency in the 3-400W range. You can barely get 80+ Gold below 500W today.
It’s *possible* DX12 may
It’s *possible* DX12 may cause a resurgence in multi-GPU setups.. But agreed we need more gold/platinum small units.
My home (VM) server is running well with a Seasonic 360W 80plus Gold..
Sure, it’s possible, but
Sure, it’s possible, but still highly unlikely. After all, DX12 multi-GPU support is as reliant on developer support as DX11 ever was, just easier to implement (just not as reliant on driver profiles). And as always, it works on a game-to-game basis, with many lacking support. Not to mention that most PC gamers buy a single ~$200 GPU, and can’t afford multiple. Sure, the potential for improved scaling and efficiency is definitely there. I just don’t see multi-GPU having a significant resurgence.
Plus, you can easily run two GTX 1070s or RX 480s off a 600W PSU. Probably even less.
Also, there is no lack of 800W+ (heck, even 1200W+) PSUs with good efficiency today. That market is well provided for already. It’s time to provide better efficiency to the mass market.