Why use a 1500W power supply?
Why use a 1500W power supply?
with sufficient wattage to power the system utilizing it with
stability. Currently, a high-end system with Intel Core i7 CPU, an X58
based motherboard, two GTX 295 graphics cards in SLI will draw around
800W at full load. Normally the choice for such a system will be a
1000W power supply, which is sufficient in providing full stability.
So we often hear the question, "do I really need a 1500W power
supply?" If you are using a system such as the one we just described,
then the answer is “yes!” When high-level computer enthusiasts are
looking for a power supply, sufficient wattage is only one of the basic
requirements. There are other important requirements that warrant
considerations as well.
Efficiency requirement :
Having
high efficiency means reduced power consumption and electricity cost.
If we use the above described high-end system as an example, equipping
it with a 1000W power supply should be sufficient, but let’s take a
look at the below efficiency graph in detail:
Nearly all power supplies achieve their highest efficiency during 50%
loading condition. The graph shows two power supplies with 80 PLUS
Silver level efficiency with the only difference between the two being
their wattage rating, one is 1000W and the other is 1500W. We can
clearly see that at around 800W loading, the 1500W power supply is more
efficient, therefore drawing less power. Some may argue that during
system idle, the 1000W power supply is more efficient so overall power
draw is still lower than 1500W. But if we calculate in detail by using
the aforementioned high-end system as an example, which has idle power
draw of around 100W to 200W, the 1000W power supply will be more
efficient by 1% to 2 %. This translates to around 3W to 1.5W of saving
(100/0.81~0.82 – 100/0.8 = 3~1.5) compared to the 1500W power supply.
Doing the same calculation with 800W system power draw, the 1500W power
supply is more efficient by also 1% to 2%, which translates to around
21W to 10.5W of saving (800/0.88 – 800/0.86~0.87 = 21~10.5) over the
1000W power supply. So the power saved at full load using a 1500W
power supply is at least seven times greater than what a 1000W power
supply can save during system idle. Even if an user spends more than
2/3 of his/her time idling and only 1/3 of the time at full or high
loading condition (such as playing games), the 1500W will use less
electricity overall.
Low noise requirement :
Modern high-end power supplies have vastly improved efficiency compared
with ones produced just a few years ago, which has resulted in
noticeably lower heat output. These power supplies are usually coupled
with large diameter fans, so they need very low fan speed to cool
properly, thus resulting in lower operating noise as well. But as
loading increases on these power supplies, their internal heat output
will increase proportionally so they are equipped with fan controller
to change speed in response to heat output. If we compare a 1000W
power supply with a 1500W power supply with similar fan control scheme
(fan start ramping up at 60% loading) on a system drawing around 800W,
we can produce the following graph to compare the expected noise level:
At idle, both power supplies have the ability to stay very quiet, but
at around 800W, which corresponds to 80% power draw for a 1000W power
supply, the fan has already ramped up noticeably higher and beginning
to sound noisy. The 1500W power supply, on the other hand, is still
operating at around half of its total capacity so the fan does not ramp
up. This shows that you can expect a 1500W power supply to be as quiet
during full load as it does in idle condition when powering a typical
high-end system.
Lifetime requirement :
Component temperature rises proportionally with increased loading so
components inside the power supply are exposed to constant high
temperature if subjected to high loading conditions. High temperature
causes faster aging of components and reduced overall lifetime. Using
the 1000W and 1500W power supplies as reference again, we set the
expected maximum operating temperature to 90% of the component
temperature rating (component temperature rated at 85℃, expected max.
operating temperature at 76.5℃) to compare their temperature rise in
the graph:
When
drawing around 800W, the 1000W power supply’s internal component
temperature increases to 68℃ (80% of the expected max. operating
temperature) and under the same condition, the 1500W power supply’s
component will only rise up to 59℃ (69% of expected max. operating
temperature). So with system power draw at the same level, we can
expect the 1500W power supply to have longer component and overall
lifetime.
From the above summaries, we believe the use of
higher wattage power supplies have tangible advantages for computer
enthusiasts or professionals using high-end system builds. The results
will nearly always favor higher wattage power supply running at half of
its capacity compared to lower wattage unit running into higher power
levels.
For more information on the SilverStone’s 1500W power supply, the Strider ST1500, please visit the following