Q-Technology QT-02300 Power Supply

Viewing page 1 of 2 pages. 1 2 Next

August 12, 2002 -- by Mike Chin

Product Q-Technology QT-02300 PSU
Manufacturer Q-Technology
Distributor Silent PC NL / CG Consultant BV

The original Q-Technology 230W power supply unit developed a mystique as a very quiet PSU at a time when it had no competition at all. Despite its plain-Jane appearance and high price tag, lots of enthusiasts were apparently swayed by the promise of quiet. Some commercial builders also utilized the Q-Technology PSU in their early quiet PC systems.

Now, with power hungry Intel P4 and AMD XP processors in dominance, Q-Technology has discontinued the 230W unit in favor of 250, 300, 400 and 460 watt models. The new models are said to carry on the quiet tradition of the original. Silent PC NL / CG Consultant BV in the Netherlands is the distributor of Q-Technology products, which are manufactured in one of the large Far East power supply factories. CG Consultants BV arranged to deliver a sample of the QT-02300 300W PSU through their Canadian agent, QuietPC.ca.

There is some confusion about different Q-Technology models, some of which are reportedly louder than others. On the Silent PC NL / CG Consultant BV web site, 6 different models of ATX power supplies are listed, all with different model numbers. One SPCR reader described another model, ATX-1125BTA QT. The fan in this 300W model is said to start off quietly, but exhibits typical thermistor-fan behavior by speeding up and becoming noisy in normal use. In response, Michael van der Jagt of Q-Technology wrote,

The ATX-1125 BTA QT reacts differently to power consumption then the QT-02300. The ATX-1125 BTA QT reacts a bit more 'extreme' to high power consumption then the QT-02300. So you can say the noise level difference between low and high power consumption is smaller with the QT-02300 then with the ATX-1125 BTA QT.

The QT-02300, then, is the quieter of the two models.


Most web retailers currently sell the Q-Technology QT-02300 for around US$76 (or equivalent). The review sample came in a retail display box without a manual.

As the photos above show, the QT-02300 is nicely finished with a proper wire fan grill for minimal air blockage and turbulence. The air intake slots on the side that normally faces the CPU and the front are surprisingly minimal, a bit reminiscent of the original Zalman PSU (ST300 BLP). It sports Active PFC, like the previously reviewed Zalman and Seasonic PSUs. (For details on Active PFC, see the text box entitled POWER CORRECTION FACTOR on the first page of the Zalman PSU review.) One of the benefits of Active PFC is automatic adjustment to any AC input voltage from 110V to 240V -- note the absence of the typical voltage selector.

A label on the side of the unit provides details of current capacity for the various voltage, along with a confusing statement: Select the right voltage! Hmm. As already mentioned, there is no voltage selector.

One other statement, With fan control, means the fan speed is controlled by a thermistor.

The fan used in the QT-02300 is an ADDA AD0812MX-A70GL. Its key specifications are as follows:

Air Flow
12 V
0.15 A
31.4 CFM
28.3 dBA

The X in the model number indicates use of the patented Hypro bearing, which ADDA claims reduces friction and noise, and prolongs service life. The GL designation further indicates low noise, which may have to do with the geometry of the blades. The rated noise is relatively low for the specified air flow. In free air, run at 12V, the ADDA fan sounds smooth and free of obvious bearing noise, but not nearly as quiet as the 21 dBA SPCR reference Panaflo 80mm "L" fan, which spins slower and pushes considerably less air. Note that in the PSU, the fan is not run at 12V but at under 6V. It is much quieter at this reduced voltage. It is the quietest fan we've encountered in a PSU after examining more than a dozen.

There are good-sized large heatsinks and the PCB wiring looks good. The thermistor for fan speed control could not be identified; one assumes it is attached somewhere close to the large coils or hidden from view on a heatsink.


This information is from the website of CG Consultant BV.

The electrical efficiency is specified as 65%, a typical figure. In theory, this means the unit requires 154W in AC power to provide 100W in DC voltage output to components in a computer, and the remaining 54W is dissipated as heat.

The DC output specifications are consistent with those for most quality 300W PSU. The combined power of 200W for the +3.3V and 5V lines is a bit more generous than most.

DC Output

Ripple & Noise

Output Load Current (A)

Combined Power


100 mV


100 mV


200 mV


200 mV


200 mV


100 mV


1 2 Next

Power - Article Index
Help support this site, buy from one of our affiliate retailers!