Reviews - Seasonic X-400 Fanless 400W
Sample Provided by: (By OklahomaWolf on Mon, Sep-13-2010)

Page 3 - Hot Testing

The hot testing phase of the review is always the more interesting part of the whole deal. My hot box is a modified ATX case with a dryer duct running between the SM-268's exhaust fan into the case via the 5.25" expansion bays. Inside the case in front of the duct, there is a 120mm 12V fan that helps pull the heat out of the duct and into the case. This fan points directly at the power supply mounting location. Two other fans are mounted in the case, an 80mm exhaust located right next to where the PSU mounts, and a 120mm 12V intake fan at the expansion slots, where you'd normally see stuff like modems and video cards and stuff.

Why do I mention all this? Well... since this hot box can reach temperatures in excess of fifty degrees, I have to be real careful with these fanless units. I've decided to mount the unit with the top grille facing up, as Seasonic intends it to be mounted. But because the unit can't cool itself actively, I still need some air moving through the hot box. So, I've decided to positively pressurize the hot box. The exhaust fan will be turned off, and the intake fan turned on. This may not heat the box up much past forty, but it should get close. Ready? Let's cook.

Results from Seasonic X-400 Fanless HOT load tests
Test # +3.3V +5V +12V DC Watts/
AC Watts
Eff. Intake/
Exhaust
Simulated system load tests
Test
1
1A 1A 5A 74.1W/
84.3W
87.9% 26°C/
25°C
3.36V 5.01V 12.17V
Test
2
2A 2A 11A 158W/
173W
91.3% 30°C/
29°C
3.34V 5.00V 12.15V
Test
3
3A 3A 16A 229W/
250W
91.6% 33°C/
32°C
3.33V 4.98V 12.13V
Test
4
4A 4A 22A 311W/
342W
90.9% 36°C/
35°C
3.32V 4.97V 12.09V
Test
5
5A 6A 28A 398W/
441W
90.2% 43°C/
42°C
3.30V 4.94V 12.06V
Test
CL1
12A 12A 0A 104W/
123W
84.6% 31°C/
31°C
3.29V 4.93V 12.18V
Test
CL2
0A 0A 33A 403W/
444W
90.8% 39°C/
39°C
3.33V 4.98V 12.06V

Imagine my surprise when I got this unit locked inside the hot box only to hear the unit saying, "Yeah, I'm going to out-awesome myself in here, Wolfy." Efficiency is up across the board, with the unit besting its own cold test numbers. This may be due to the fact that the unit is now being actively cooled in the hot box, whereas it was just sitting there out in the open heating itself up in the cold tests.

Over on the voltage readings, the 3.3V and 5V are not quite doing as well as they were cold. However, the difference is very slight indeed, and could be due to the fact that the 3.3V/5V VRM is located on the front of the unit. You know - the area that was being directly blasted with hot air from the SunMoon. I think we can cut these two rails some slack, here. The 12V rail... now that's where we see some real action. Not only did it start out at the same rock solid number it did cold, it improved its regulation all the way down to test CL2. Very nice.

Let's have us a look at the scope shots and see if the niceness continues.

Oscilloscope Measurements - Seasonic X-400 Fanless

Test #
+3.3V
+5V
+12V
Test
1
Test
2
Test
3
Test
4
Test
5
Test
CL1
Test
CL2

Hubba hubba! Yes, the niceness does indeed continue. How does 30mV at worst for the 3.3V and 12V rails sound? What about 20mV for the 5V rail? Sounds excellent to me. You know, not many 400W units perform like this one has so far. I am very impressed so far.



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