We made several tests with this power supply as described in the article Hardware Secrets Power Supply Test Methodology.

First we tested this power supply with five different loads patterns, trying to pull around 20%, 40%, 60%, 80% and 100% of its labeled maximum capacity (under “% Max Load” we list the actual percentage that was used), watching how the reviewed unit behaved under each load. On the table below we list the load patterns we used and the results for each load.

If you add all the powers listed for each test you may find a value different from what posted under “Total” below. Since each output can have a slight variation (e.g. +5 V output working at 5.10 V) the actual total amount of power being delivered is slightly different from the calculated value. On “Total” row we are using the real amount of power being delivered, as measured by our load tester.

The +12V1 and +12V2 inputs listed below are the two +12 V independent inputs from our load tester and during all test both were connected to the single +12 V rail present on the power supply.

Toughpower XT 750 W presents an excellent efficiency between 84% and 86% if you pull up to 60% from its labeled capacity, i.e. up to 450 W. Pulling 80% from its maximum load (i.e. 600 W) efficiency was still good at 83%. But at full load (750 W) efficiency dropped to 80%.

You have to keep in mind that the 80 Plus organization measures efficiency at a room temperature of only 23º C, which is impossible to achieve inside a PC. We test power supplies at a room temperature at least double that and we consider our results to be more realistic. Since efficiency drops with temperature, usually our numbers are lower than the ones achieved by 80 Plus.

Voltage stability was the highlight from Toughpower XT 750 W. All outputs (including -12 V) were within 3% from their nominal values. Translation: they were closer to their nominal values than allowed by the ATX specification, which sets a 5% margin (10% for -12 V).

Noise and ripple were the problem on Toughpower XT 750 W. While ripple and noise levels were in all tests within admissible range on +5 V and +3.3 V outputs, they reached and passed the 120 mV limit on +12 V output during test number five, when the unit was delivering 750 W. During test four noise and ripple at +12 V were around 100 mV and during test three they were around 70 mV.

Below you can see the results for test number five. As we always point out the limits are 120 mV for +12 V and 50 mV for +5 V and +3.3 V and all numbers are peak-to-peak figures.

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Figure 17: +12V1 input from load tester with power supply delivering 744.9 W (115.4 mV).

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Figure 18: +12V2 input from load tester with power supply delivering 744.9 W (130.6 mV).

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Figure 19: +5V rail with power supply delivering 744.9 W (17.4 mV).

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Figure 20: +3.3 V rail with power supply delivering 744.9 W (16.4 mV).

Since this unit was running already outside ATX specs during test number five, we decided not to publish our traditional overload tests. When we tried to overload this unit, it kept shutting down after a while, showing that one of its protections entered in action. The idea behind of overload tests is to see if the power supply will burn/explode and see if the protections from the power supply are working correctly. This power supply didn’t burn or explode and it shut down when we tried to overload it.