And now, the fun part. I will lock this here Coolermaster in that there modified ATX case and pump all the heat output from the SunMoon in there to get the ambient temperature nice and hot. I expect that the intelligent fan controller will have its work cut out for it. Hey, fan controller, name the English king who died during the battle of Hastings.

"What's a battle?"

Folks, the fan controller has officially turned into Ralph Wiggum. I'm scared for this power supply.

Facepalm.

The unit lasted until test five, and then two minutes and twenty five seconds later shut itself down. I was able to get it restarted once it cooled off, indicating that the overtemp protection was in play, but then it shut down again when I tried for test five again, thereby failing the hot tests due to the inability to make it all the way to the end. The highest ambient temperature seen was forty two degrees before shutdown with exhaust temps reaching the low sixties. It is abundantly clear to me that this unit's 750 watt rating is not intended to be reached anywhere near the forty degree mark, and to be honest I'm not sure I'd care to run it to 750 watts very often at room temperature either, if I'm going by the numbers from the cold tests.

In terms of the efficiency and voltage readings, there are no surprises here. Regulation is less stable and efficiency is down. Before the overtemp protection stepped in, efficiency in test five was down to 76.6% and falling.

Let's take a look at the oscilloscope shots and see what the outputs looked like.

Oscilloscope Measurements - Coolermaster GX-750
Test #	+3.3V	+5V	+12V
Test 1
Test 2
Test 3
Test 4
Test 5
Test CL1
Test CL2

Facepalm. Look at those 3.3V shots. That is out of ATX spec, at 69mV by test five. Heck, it was out of spec already by test three. The other two rails were fairly well behaved, at 33mV for the 5V and 52mV for the 12V, but there's just no ignoring that 3.3V ripple.

I hear some of you asking whether or not I did the right thing in offering Coolermaster another chance at passing my tests. I did indeed. And they took me up on the offer, saying that I had received a pre-production sample and that they expected the retail units to be better behaved. I was told the replacement sample would be sent right out. That was several months ago, and the replacement has yet to appear. Whether it got lost in shipping or never got sent I don't know - all I know is I have bills to pay and the show must eventually go on.

And now, we're going to take the unit apart.