Testing

The PAC 400 specs don’t provide much real information about the TEC but from basic voltage and current measurements we can extrapolate some useful numbers.  During operation at 12 VDC the PC AirCon TEC pulled 4.1 Amps (not including the two fans).  This defines the TEC’s input power at 49 watts (12.0V x 4.1A = 49.2 watts).  If we assume a generous efficiency of 40% (yes, Peltier devices are not very efficient) we can approximate the TEC’s Q-max value (heat pumping capacity) at 20 watts (49.2 watts x 40% = 19.7 watts).  Unfortunately this does not bode well for stellar cooling performance. 

 

Note: Q-max is not at all the same thing that Waffer Technology defines as System Cooling Performance (SCP), which takes into account the flow rate of air, specific heat of air, and the differential temperature of the room air to internal case air.

 

I tested the PC AirCon on three different systems (actually two working systems and one empty case).  As we just discussed in the section on installation, where you mount the PAC 400 will have a large effect on case cooling performance.  Another big factor is how much air is flowing thru your case before you install the PC AirCon.  If you already have good airflow then the PC AirCon may have little affect but if you have minimal airflow and can position the unit so that the cool air is directed towards the components that need cooling, then it may work well.

 

PC AirCon PAC400 - Cases and Cooling 20

 

To establish a baseline, I mounted the PC AirCon in a typical mid-tower ATX case that was empty except for a 400 watt ATX power supply.  I installed a thermocouple inside the case (central CPU area) to measure the internal case air temperature and used a second thermocouple to measure the temperature of the ambient room air being drawn into the bottom of the PC AirCon.  This configuration represents ideal conditions (no case air flow except for PSU fan and no thermal load), which should produce the lowest temperatures possible.

 

PC AirCon PAC400 - Cases and Cooling 21

 

Under these conditions, the PC AirCon was able to lower the average internal case air temperature by ~3ºC.  The cool air blowing out of the PAC 400 was actually ~5ºC below ambient but by the time it mixed with the larger volume of internal air the cooling effect was reduced.

 

The second system I tested was my DAQ rig housed in a Cooler Master Centurion case and loaded with all the usual goodies.  I mounted the PC AirCon in the top drive bay but found it made no measurable difference in component temperatures, whether it was running or turned off.  I suspect the PC Power and Cooling power supply was just sucking in the cool air coming out the back of the PAC 400 and exhausting it straight out of the case.  With the PC AirCon mounted in top position, the cool air never made it down to other areas of the case where additional cooling could have been useful.

 

For a final test I temporarily mounted the PC AirCon in the bottom 5-1/4′ drive bay of a Lian Li PC-68 aluminum case so the cool air was blowing on the CPU heatsink fan, RAM and NB cooler.  In this case I saw the full load CPU temperature drop an average of 1°C and internal case temperature drop <1°C.  But the noise level also increased significantly and I lost the use of one 5-1/4′ bay and one 3-1/2′ drive bay.

 

This system also rebooted several times when the PC AirCon was switched to cooling mode while the computer was up and running.  The power supply is an Antec TruePower 480 watt with plenty of reserve power on the 12V rail.  I suspect the power supply was responding to the sudden increase in current as if it were a short circuit.  I had no problems when the computer was started up with the PC AirCon already in cooling mode.

 

I measured the noise generated by the PC AirCon in all three modes of operation.  Sound pressure level readings were taken 3′ in front of the computer with the PC running.  The average background noise level in the room was ~30 dBA.

 

PC AirCon PAC400 - Cases and Cooling 22

 

The PC AirCon is certainly not silent, but depending on your level of noise tolerance and background noise level, may be acceptable.  To my ears, anything above 40 dBA becomes noticeable and potentially distracting.

 

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