Advanced Transient Response Tests

In these tests, we monitor the PSU's response in two different scenarios. First, a transient load (10 A at +12V, 5 A at 5V, 5 A at 3.3V, and 0.5 A at 5VSB) is applied to the PSU for 200 ms while the latter is working at 20% load. In the second scenario, the PSU, while working at 50% load, is hit by the same transient load. In both tests, we measure the voltage drops the transient load causes using our oscilloscope. The voltages should remain within the regulation limits defined by the ATX specification. We must stress here that these tests are crucial since they simulate transient loads a PSU is very likely to handle (e.g., booting a RAID array, an instant 100% load of CPU/VGAs, etc.). We call these tests Advanced Transient Response tests, and they are designed to be very tough to master, especially for a PSU with a capacity below 500 W.





The +12V rail performed very well, hardly deviating in both tests. The 5V and 5VSB rails also did well, but the 3.3V rail deviated greatly, which lead to a failure in the second test. Its failure is a shame, especially with such a well-performing PSU as the 1600 T2—we didn't expect it to fail. However, we should remind you that the+12V rail's performance matters the most since the 5V and 3.3V rails are hardly tasked, which is also why they are classified as "minor".

Below are the oscilloscope screenshots we took during Advanced Transient Response testing.

Transient Response at 20% Load

Transient Response at 50% Load

Turn-On Transient Tests

We measure the PSU's response in simpler scenarios of transient load—during the power-on phase of the PSU—in the next set of tests. In the first test, we turn the PSU off, dial the maximum current the 5VSB can produce, and switch on the PSU. In the second test, we dial the maximum load the +12V rail can handle and start the PSU while the PSU is in standby mode. In the last test, while the PSU is completely switched off (we cut off power or switch the PSU off by flipping its power switch), we dial the maximum load the +12V rail can handle before switching the PSU on through the loader and restoring power. The ATX specification states that recorded spikes on all rails should not exceed 10% of their nominal values (e.g., +10% for 12V is 13.2V and 5.5V for 5V).


There was minor spike at 5VSB, but the waveforms were pretty smooth in the other two tests. EVGA's PSU did very well overall in these tests.