My load tests are performed using a SunMoon SM-8800 active load tester. The tester allows me to pre-program up to 10 different loads and apply them to a power supply at the touch of a button. The loads are, from test 1 to 8, 10%, 20%, 30%, 40%, 50%, 60%, 80% and 100%. The last two tests are crossloads where I put either the maximum load on the no-primary rails (the +3.3V and +5V) or the +12V alone.

This power supply is supposed to have separate +12V rails, and I have the capability and will load each of these +12V rails. But I will only report the highest +12V voltage for each load as lower voltages can be blamed on the resistance in the cable or connectors.

Let's first see how the power supply did at room temperature:

First, let's look at Test 0. This is when the PSU is plugged in with a load on the +5VSB rail, but the PSU isn't actually on, it's only in standby. With an efficiency of 77.3%, we find the efficiency here just above average.

Now let's have a look at the voltage regulation, starting with the +3.3V rail. We see the +3.3V drop from +3.39V to +3.26V going from test 1 to 8. That's a drop of .13V or 4%. The +5V dropped from +5.06V to +4.93V, which is also a drop of .13V, or 2.6%. These drops in voltage reflect average performance.

The +12V dropped from +12.27V to +11.83V. Unfortunately, that's a drop of .44V, or 3.6%. Although this is within spec, it's somewhat disappointing to see a power supply of this caliber exhibit such a large drop in voltage.

Crossloading the power supply, either with all of the load on the +12V or the non-primary rails, has no effect on the power supply's performance. This is to be expected of power supplies that use DC to DC VRM's for the non-primary rails.

Looking at the efficiency, we find that this is certainly a very efficient unit, but does it meet 80 Plus Platinum standards? For a power supply to make 80 Plus Platinum, it needs to be 90%, 92% and 89% efficient at 20%, 50% and 100% loads. Our tests reveal efficiency numbers of 90.1%, 90.3% and 87.1%. Just like the MaxRevo 1350W we reviewed, we fell short at 100% load. But here we also fell considerably short at 50% load. This gives me reason to retest the Platimax 1200W using the exact same numbers as 80 Plus.

Here we find our 20% load is actually a little lower, but the 50% load efficiency has increased significantly and easily meets 80 Plus Platinum expectations. At 100% load, however, we don't see any improvement in efficiency by fudging our numbers.

Now we're going to take the heat generated by the load banks within the SunMoon and pump that back into the power supply to see how the Platimax reacts to running under high temperatures...

It seems like neither the +12V nor the +5VSB didn't like the higher temperatures. Both voltage dropped a lot more than they did at room temperature when subjected to high temperatures.

Now let's have a look at the ripple, courtesy of our USB Instruments Stingray oscilloscope...

Oscilloscope Measurements for Enermax Platimax 1200W
Test #	+3.3V	+5V	+12V	+5VSB
Test 1
Test 2
Test 3
Test 4
Test 5
Test 6
Test 7
Test 8
Test 9 (CL 1)
Test 10 (CL2)

If we're going to keep seeing power supplies with this little ripple, I'm going to have to increase the V/div on my oscilloscope!

Now let's look for overshoot and rise-time issues by hitting the Platimax with full loads going from full off and stand by...

Overshoot Transient Testing for Enermax Platimax 1200W
Off to VSB On	VSB to Full, 12V	Off to Full, 12V

Looking at the first test, we see that the rise rime on the +5VSB rail is rather slow. It takes a full 30ms to get up to 5V. But the fact of the matter is, the voltage is still within spec and it does get there within the 20ms specification, so this is a pass.

Looking at the +12V rail, both going from standby and full off, we find that we hit +12V within only 5ms and with hardly any overshoot to speak of.