X-bit labs

Powerful Power Supply Units Roundup (page 11)

Category: Other

by Oleg Artamonov

[ 01/28/2005 | 05:24 PM ]

Unlike the above-described units, the models from OCZ have neither passive nor active power factor correction, so their power factor is only about 0.7 as my measurements show. The power efficiency, on the contrary, goes as high as 88 percent – much above the results of the Antec and the BeQuiet. By the way, this is a refutation of the common opinion that active PFC increases the efficiency factor of the power supply. As a matter of fact, PFC doesn’t greatly affect the efficiency in general.

The speed of the PSU fans, contrary to my expectations, doesn’t depend heavily on the load. Yet in spite of a higher speed than with the BeQuiet P4-450W, the unit from OCZ wasn’t much noisier. There’s no total noiselessness here, too, as the light buzz of the fan can still be heard. The PSU is cooled well, even though the numbers in the table above are a bit lower than the real values – I couldn’t put the thermode in the most appropriate location when taking down the measurements.

Now let’s proceed to the single difference between the results of the two PSUs from OCZ, i.e. to their cross-load characteristics. The CLC of the OCZ-470ADJ model looks exactly like the CLC of a unit with dedicated voltage regulators should look:

Like with the Antec True430P, the CLC of this power supply is only limited by its specification, not by the deviation of the voltages out of the norm. Moreover, even the small initial deviation of the +12v voltage (the +12v diagram is all yellow because of it) can be easily corrected with the PSU’s trimming resistors, if necessary.

Alas, it’s not that well with the higher-wattage OCZ-520ADJ unit. At first it was going to draw an ideal diagram as its junior mate had done, but when the load on the +5v rail became very high and on the +12v rail very low, its regulator would lose stability, changing the output voltages in a leap. You can see that in the CLC diagram as random-shaped white areas that show where the voltages deviated beyond the norm. Anyway, this unit handles power loads of up to 200 watts inclusive on the +5v and +3.3v rails without problems.

So, OCZ Technology has debuted in the PSU market with some success. The OCZ-470ADJ is in fact an example of how a high-quality universal power supply should be made: a wide range of output currents (the unit fully complies with the ATX12V 2.0 standard, but can give out above 250 watts on its +5v and +3.3v rails); a number of output connectors, including two separate connectors with dedicated, although simple, LC filters; neat assembly; good looks; quiet operation.

The only reprimand to the other unit, the OCZ-520ADJ model, concerns its instability when the load is high on the +5v rail and low on the +12v. Still, it is rather hard to distribute the load in such a way in a real computer system, so I don’t consider this disadvantage as a serious one.