Reviews - Seasonic X-650 650W
Sample Provided by: (By OklahomaWolf on Sun, Oct-11-2009)

Page 2 -

Once again, we come to the fun part - the load testing. I'll be doing this the way I usually do this. That is, I'll hook up the Seasonic here to my trusty load tester and let it do all the work for me. The load tester in question is a SunMoon SM-268 automated test environment that is capable of electronically loading and testing ATX power supplies up to around a thousand watts or so. Joining it will be a Brand 4-1850 power meter, a USB Instruments DS1M12 oscilloscope, a dual probe thermometer, and a multimeter.

Starting things off will be a sequence of five balanced progressive and two crossload tests. These are done at room temperature, with loads ranging from 20% to 100% of full rated power for the progressive tests, and then loads unfairly lopsided toward either the combined 3.3V/5V rails or the 12V rail depending on which crossload test you're looking at. This will give us some idea on how well this puppy is supposed to bark, roll over, chase its tail, or lie down.

Following this, I'll run a special low load test. See, 80 Plus only starts testing at 20% of full power, going up from there. I want to see what happens at a much lower load than that. Why? It's quite simple... I'm a vicious evil power supply torturing madman. But really, it's because the lower you go down the power tree, the less efficient these power supplies get. I want to see how a Gold unit does at load levels below where 80 Plus starts at.

From there, I'll run my overshoot transient tests. That's where I go looking for turn on spikes that go out of ATX spec. What is the spec, you ask? Well, it's for those turn on spikes to stay below 10% above mean value, and nothing going into the negative voltage side. In other words, for the 5VSB rail, the spike can't go above 5.5V or below 0V.

At last, the real fun will begin. I'll lock the unit in my hot box and repeat the initial seven room temperature tests. That tends to sort the real power supplies from the Powmaxes.

Results from Seasonic SS-650KM COLD load tests
Test # +3.3V +5V +12V DC Watts/
AC Watts
Eff. Intake/
Simulated system load tests
1A 1A 10A 134W/
90.5% 23°C/
3.36V 5.01V 12.25V
2A 2A 20A 269W/
92.1% 29°C/
3.35V 4.99V 12.23V
3A 3A 30A 401W/
91.6% 24°C/
3.34V 4.98V 12.22V
4A 4A 40A 533W/
90.6% 24°C/
3.33V 4.96V 12.18V
5A 5A 49A 653W/
89.5% 25°C/
3.32V 4.95V 12.14V
14A 14A 1A 133W/
87.5% 29°C/
3.33V 4.96V 12.28V
0A 0A 54A 658W/
89.6% 25°C/
3.33V 4.98V 12.13V

*Unit remained in fanless operation for duration of test

Hello? Is this thing on? Such were my first words when I powered up this unit for testing. The fan twitched and immediately stopped. It didn't turn on again until test three. And then it turned off again for crossload test one. It seems that Seasonic wasn't joking about this being a quiet unit... you just can't get much quieter than fanless. I like that the fan twitches just to let you know the unit isn't dead or something.

You say the efficiency numbers are mighty impressive looking? Well, I have to agree with you on that one. With the lowest number still pushing 90% in the progressive tests, this unit is the new efficiency champion around here. I simply haven't tested anything as efficient across the board as this unit. Just look at the heavy 3.3V/5V crossload test... I have trouble getting these units to beat 80% in that test, never mind 87.5%! If all you care about is efficiency, you can pretty much stop reading right here and go buy one of these right now.

Me, I care about voltage regulation too, so I'm continuing on. See those numbers up there? I do have to admit I have seen better stability than that in the past. But, if that can be considered bad news, here's some good news - I haven't seen too many units do better. The unit is holding to Seasonic's 3% promise. Indeed, the 12V rail is doing 1%, while the others are within 2%. That's exceptional.

Results from Seasonic SS-650KM low load test
+3.3V +5V +12V 5VSB -12V DC Watts/
AC Watts
9.6% 1A 1A 4A 0.5A 0.2A 62.4W/
3.37V 5.00V 12.27V 5.08V -12.08V

In looking at the low load test results, I'm starting to wonder if I shouldn't have put a big red warning logo above it to warn you to sit down first. I heard crashing noises - I hope you guys are ok. Personally, I was already sitting down when I did the math for this table, else I'd be in the hospital right now. There just isn't room for a six and a half foot tall guy to fall safely in this room and not take serious injury.

88.8% at a below 10% load level. Good golly. Maybe I should go lie down for a while... I'm getting light headed again just looking at that number. This here Seasonic platform seems hell bent on breaking records today.

Overshoot Transient Testing - Seasonic SS-650KM
VSB to Full, 12V
Off to Full, 12V

Sadly, this here Seasonic platform has just come up as merely average to slightly above average in this test. No, none of these spikes are getting up to that 10% over mean value level, but they aren't really that well suppressed either. Past Seasonic platforms like the M12D were better performing here. This is nothing you should worry about, and this will not have much if any impact on the final score, but it's a wee bit of a letdown to go from the efficiency numbers to this.

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