Cross-Load Voltage Stability
The most important +12V rail is not very stable in this test. Its voltage is 2 to 3% off the required level at loads up to 300 watts. The result is good but the other PSUs in this review are better in this respect.
You can note, however, that the +12V voltage gets more stable at higher loads, so you shouldn't worry that your top-end graphics card might fail due to poor power supply when running a heavy 3D game (such problems can occur even if the voltage is no more than 5% off as permitted by the industry standard).
The rest of the voltages are blameless, staying within 2% of the required levels.
Thus, the OCZ ZX 1000W would be perfect if it were not for the large 3% zone in the +12V diagram.
Well, this is not a critical downside, of course. We wouldn’t even notice it in a cheaper and less efficient product or on a less loaded power rail. But the OCZ ZX 1000W being a rather expensive, high-wattage and high-efficiency PSU, we want it to be more stable in terms of the +12V voltage.
Output Voltage Ripple
The high-frequency output voltage ripple is very weak on the +12V rail and two or three times lower than the permissible maximums on the other power rails.
We’ve got the same picture at the double frequency of the mains.
Temperature and Noise
The OCZ ZX 1000W is cooled by a 140mm 7-blade Yate Loon fan. It is the D14BH-12 model with a rated speed of 2800 RPM.
The fan starts out at a speed of 900 RPM and keeps it until a load of 300 watts. It accelerates then but, despite the high rated speed, gets only as fast as 1700 RPM at full load.
On the other hand, accelerating at a rather low load and having a top speed of 1700 RPM, the fan turns out to be the noisiest among the cooling fans of all the PSUs in this review. Like the above-discussed Cougars, the fan of the OCZ ZX 1000W produced some mechanical sounds besides pure aerodynamic noise.
Efficiency and Power Factor
The power factor is high, just as you can expect from a PSU with active power factor correction.
At the three reference loads (20%, 50% and 100% of the full output power), the PSU was 88.3%, 90.9% and 88.4% efficient. Its peak efficiency of 91.5% was achieved at a load of 423 watts.
These numbers are not as impressive as those of the lower-wattage models from Cooler Master and Seasonic, but better than the results of the Cougar PSUs which are similar in wattage. As opposed to the latter, the OCZ ZX 1000W is somewhat better than the basic requirements of the 80 PLUS Gold certification.
The standby source copes with its job, keeping its voltage within 2% of the required level.
The closest opponent to the OCZ ZX 1000W is the Cougar GX G1050. While being very close to each other in terms of their retail price and wattage, their operating parameters differ greatly.
The OCZ is superior across nearly all of electrical parameters and also features all-modular design. However, it is inferior to its opponent in acoustic comfort and UPS compatibility. Its exterior design, if you care about this factor, is less attractive, too. It's up to you to choose what parameters are more important to you.