GMX SmartQC ATX-550H Review

Load Testing

When it came time to start the testing, the fan decided to play dead. I tried turning it by blowing into it to help it start, but it was dead, which is strange since it worked for the SmartQC test. Either something has failed already or the fan controller doesn’t turn it on when the unit is cool. Just in case the fan had really stopped working, I decided to use the load tester’s exhaust duct to cool the unit. When the exhaust air duct is completely ‘closed’ over a power supply, the exhaust air from the load tester can only exit through the power supply. Since the air doesn’t get hot unless the tester is pulling more than 400W of load and the two fans pump out over 240CFM each, this should be more than enough cooling to make up for a failed fan. With that sorted, let’s get on to the testing.

Test 1 (118.05W Load – Cold)

Rail Load Voltage Ripple
12V 4.87A 12.17V 27.0mV
5V 5.02A 5.02V 19.0mV
3.3V 10.09A 3.33V 38.0mV
−12V 0A −11.80V 14.8mV
5Vsb 0A 5.03V 42.8mV
AC Power 146.26W
Efficiency 80.71%
Power Factor 0.6

 

Test 2 (201.86W Load – Cold)

Rail Load Voltage Ripple
12V 9.79A 12.24V 42.8mV
5V 9.88A 4.94V 22.2mV
3.3V 10.03A 3.31V 33.8mV
−12V 0.1A −12.36V 17.0mV
5Vsb 0.99A 4.97V 11.6mV
AC Power 256.88W
Efficiency 78.58%
Power Factor 0.59

 

Test 3 (259.86W Load – Cold)

Rail Load Voltage Ripple
12V 14.57A 12.14V 53.2mV
5V 9.96A 4.98V 20.2mV
3.3V 10.06A 3.32V 31.4mV
−12V 0.11A −12.77V 23.0mV
5Vsb 1.00A 4.98V 11.8mV
AC Power 334.34W
Efficiency 77.72%
Power Factor 0.58

 

The fan was definitely not working. It never moved, right up until the unit exploded about 30 seconds into test 4 (which would have been about 320W). Before that, though it wasn’t doing too bad in terms of voltage regulation and ripple suppression. The voltages all stayed within 2% of their nominal values on the + rails and 7% on the −12V rail. The ripple was below half the maximum allowed on all rails except the 3.3V, although even there, it was well in spec. The efficiency, though, wasn’t so good. It barely managed 80% on 230V during Test 1. With a lower input voltage, it would have been below 80% the whole time. The power factor is rather strange too. There is definitely a big yellow passive PFC coil stuck to the front of this unit, but PPFC typically results in a power factor of over 0.7. The best this unit could manage was 0.6.

Rail Test 2 (201.68W) Test 3 (259.86W)
12V
5V
3.3V
−12V
5Vsb

 

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