OCZ 780W ModXstream PSU
To provide our readers with the most accurate results, Overclock3D uses a custom-built PSU load tester on all reviews. This not only gives much more reliable results than the testing methods employed by other sites, but also allows for all current and future review results to be compared side-by-side. The following table shows the load (in watts) that was applied to the OCZ ModXstream during testing.
With 0 load the 3.3v line is over-volted slightly but once the load is applied and increased the voltage levels out and is pretty stable throughout the testing period, only dropping below standard as we neared the PSU's limit.
Once more we see that the 5.0v line is slightly over-volted and doesn't drop below standard throughout the PSU load testing. Significantly the rail was very stable ensuring a smooth power delivery to your components.
At the 'money' end of the testing we come to the 12v lines which is a judge of how good a PSU really is. Powering your motherboard, CPU and GPU's, a solid 12v line is essential to maintaining stability over long periods of time. In the OCZ ModXstream's case, we see that it has four rails all of moderate stability with a little over 0.2v movement across the rails when maximum load was applied. It appears that our concerns over the internal layout were unfounded as all the rails have performed well and would easily power a high spec PC without so much of a hiccup.
Efficiency tests are performed by measuring the wattage consumed by the power supply at the mains (Mains Draw) against the power consumed by the OC3D power supply stress tester (PSU Load). These results may not be 100% accurate, but have proven to be extremely close to results obtained from professional equipment.
In testing we found the OCZ ModXstream managed to exceed its 80% efficiency rating by over 3% and reaching a phenomenal 86.66% rating at full load which is very impressive indeed, especially when considering this is above the actual power rating of the PSU @ 799w.
Temperature, Fan Speed & Noise
As with all components in the modern computer system, the performance of a PSU can be directly affected by heat. Excess heat inside the PSU can easily have a negative effect of the maximum power output of the unit and lead to voltage instability. For this reason, Overclock3D includes temperature recordings taken from the PSU's exhaust using a thermal probe to highlight any potential issues that the PSU might have obtaining its rated output.
Heat is the number one cause for component failure in a personal computer so it is very important that the powerplant is sufficiently cooled. With the OCZ we found that the heat expelled from the unit was very hot indeed, even with the fan running at full tilt, the heat was a scorching 72c. Obviously those little heatsinks were working overtime in cooling the mosfets down but at this heat I do have a few concerns about the lifespan of the PSU. OCZ however have faith in the longevity as they provide an industry leading 3 year 'PowerSwap' warranty. As expected as the fan RPM rose so did the noise but the fan was still relatively quiet in comparison to other fans found in your average PC case so would not be too intrusive should you fully utilise the ModXstreams supply.
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