750 Watt at 50°C & 90V AC Input – This is the industrial standard in which the
operating temperatures are expected to be in the high 40°C and up to 50°C.
In addition to temperature, power supplies becomes more efficient as the AC
input voltage increase, as a reference, the power outlet in USA is usually
120V while in Europe they are normally up to 220V ~ 230V. The country with
the lowest voltage is Japan at 100V. So a power supply that can achieve
500W in Europe may not be able to output at the same wattage in other
countries (The fanless ST30NF is one example, it is rated to 300W @ 220V and
250W @90V). Here is a link to power around the world.

75zfb  SilverStone ST75ZF @ 950w Continious

When the condition is changed to 25°C @ 90V AC input, the ST75ZF can output
up to 950W continuously (not just peaking for a few minutes). This
will give power users a good idea of what they can expect if the ST75ZF is
used in a well ventilated enclosure where power supply intake temperature is
similar to room temperature. Since most users will also be using the ST75ZF
with AC input at more than 90V, they can expect to achieve 950W fairly
easily.
SilverStone updated their specification table as seen in their ST75ZF
product page.

Readers feel free to discuss and post queries here.

750 Watt at 50°C & 90V AC Input – This is the industrial standard in which the
operating temperatures are expected to be in the high 40°C and up to 50°C.
In addition to temperature, power supplies becomes more efficient as the AC
input voltage increase, as a reference, the power outlet in USA is usually
120V while in Europe they are normally up to 220V ~ 230V. The country with
the lowest voltage is Japan at 100V. So a power supply that can achieve
500W in Europe may not be able to output at the same wattage in other
countries (The fanless ST30NF is one example, it is rated to 300W @ 220V and
250W @90V). Here is a link to power around the world.

75zf  SilverStone ST75ZF @ 950w Continious

75zfb  SilverStone ST75ZF @ 950w Continious

When the condition is changed to 25°C @ 90V AC input, the ST75ZF can output
up to 950W continuously (not just peaking for a few minutes). This
will give power users a good idea of what they can expect if the ST75ZF is
used in a well ventilated enclosure where power supply intake temperature is
similar to room temperature. Since most users will also be using the ST75ZF
with AC input at more than 90V, they can expect to achieve 950W fairly
easily.
SilverStone updated their specification table as seen in their ST75ZF
product page.

Readers feel free to discuss and post queries here.