The PSU worked normally at its full load of 1000W. Unfortunately, it couldn’t work with my UPS (APC SmartUPS SC 620): at a load of only 300W there was a characteristic bubbling noise from the UPS and it would shut down in 20-30 seconds, reporting overload.
The high-frequency pulsation of the output voltage is normal on the +5V and +3.3V rails. Its peaks match the permissible maximum of 50 millivolts.
There were no low-frequency output pulsations as well, except the situation when the outputs of two different sources – 12V1 and 12V2 – are closed with one another. However, this is impossible in an actual computer system, because different graphics card power connectors are not directly connected to each other but to a special circuitry that allows balancing the load to ensure that none of the connectors will get overloaded.
The voltages are not very stable, either. Such results could be expected because the 1200 and 1500W models from Thermaltake based on the same platform hadn’t been any better.
The +12V voltage is good, deflecting by no more than 3%, but the +3.3V voltage violates the 5% limit at high loads. As a result, you cannot get the full 1000 watts from this PSU while staying within the voltage limits defined by the industry standard.
Although a modern computer doesn’t make much use of the +3.3V voltage (most of the components are powered by the +12V rail), that’s not a good thing. On one hand, a computer will work with the HX1000W, especially as it is not so easy to create a load of 1000 watts. Even a system with two Radeon HD 4870 X2 cards and a top-end CPU will consume much less. On the other hand, I have seen a lot of 1000W power supplies that delivered stable voltages. And the HX1000W doesn’t offer any advantages that would make up for this problem.
The PSU is 85% efficient at the maximum but its efficiency lowers to 80% at full load. This is a normal result. The power factor is rather odd (it usually grows up along with the load) but higher than 0.9 overall.
Noise is a most important factor for a 1000W power supply. As you may know from our reviews, early 1000K models were not quiet even under low loads.
The HX1000W is better in this respect. Its fan is rotating at about 1000rpm at loads up to 350W, making the PSU comfortable if not silent. Then the fan accelerates, reaching a speed of 2050rpm. The airflow is audible but acceptable, especially if you imagine how noisy the coolers of CPUs and graphics cards that consume so much power would be. Thus, the HX1000W is a rather quiet PSU as 1000K models go and average in terms of noisiness if compared with PSUs of other wattages.
Although the Corsair HX1000W has better results in my tests that Thermaltake’s PSUs based on the same platform that I tested earlier, I cannot call the results satisfactory. The poor stability of the +3.3V rail prevents this power supply from delivering its full declared output power. Moreover, the PSU could not work normally with my UPS. This is all rather disappointing because the HX1000W might claim to be among the best 1000K power supplies in its other parameters such as the selection of connectors, quality of manufacture, noisiness. Hopefully, the manufacturer is working upon this platform to get rid of its drawbacks.