Seasonic X-Series 1250W (XM2) Power Supply

X-Series 1250W (XM2) – Overshoot Transient Tests
VSB On	VSB to 100%, 12V	Off to 100%, 12V

We’re almost at the hotbox portion of the review, but first, a peek at the power on spike test scope shots. All three images show excellent performance, with an absolutely perfect 5VSB rail and a nearly perfect 12V rail. This is pretty much identical to what we got on the older version. No complaints here.

Now, the hot box. Since it’s about a besquillion degrees in the lab today due to that “summer” thing that started five minutes ago and should be over any second now, I’m going to flip the Seasonic into fully fanned mode and turn on the auxiliary hot box exhaust fan. I’m certain this unit will handle the heat better than I could, but I don’t think I want to sit in here all afternoon waiting for the load testers to cool down enough to switch off afterwards.

So, let’s see how hot things get. I’m betting we still see well over forty degrees.

X-Series 1250W (XM2) – Hot Load Tests
Test #	+3.3V	+5V	+12V	DC Watts/ AC Watts	AC Input	Eff.	P.F.	Intake/ Exhaust
Progressive Load Tests
1	2A	2A	19A	252.7W/ 279.6W	119.0V	90.4%	0.979	32°C/ 32°C
	3.34V	5.04V	12.16V
2	4A	4A	38A	502.7W/ 547.9W	117.9V	91.8%	0.990	36°C/ 40°C
	3.34V	5.04V	12.15V
3	5A	5A	48A	635.0W/ 694.7W	116.7V	91.4%	0.993	38°C/ 44°C
	3.34V	5.04V	12.15V
4	8A	8A	77A	1015W/ 1132W	116.2V	89.7%	0.997	42°C/ 52°C
	3.33V	5.02V	12.15V
5	10A	10A	96A	1264W/ 1437W	114.9V	88.0%	0.997	46°C/ 62°C
	3.32V	5.02V	12.12V
Crossload Tests
CL1	18A	18A	0A	155.1W/ 189.2W	117.4V	82.0%	0.989	36°C/ 40°C
	3.32V	5.02V	12.18V
CL2	0A	0A	104A	1264W/ 1431W	112.9V	88.3%	0.997	45°C/ 59°C
	3.34V	5.03V	12.11V

Ha! We almost hit fifty degrees anyway. And the unit just purred right along with no problems.

In fact, the unit is still up across the board from the old model for efficiency. It doesn’t seem to be straining at all in there.

But how good is the voltage regulation? Is this unit able to catch up to the older model? Well, on the 3.3V rail I see 0.6%. On the 5V rail, I find 0.4%. So, the 5V rail is up and the 3.3V rail is down. And the big one, the 12V, is also down… we’re now at 0.3% on that rail. Which is still pretty dadgum impressive, considering the amount of power you have going on there. Our average for scoring will be 0.43%. Still well above excellent, but only about half as stable as the older model.

So, we do have an improvement in this version when it comes to efficiency, but that’s all it improves on so far. What about ripple suppression?

X-Series 1250W (XM2) – Oscilloscope Tests
Test #	+3.3V	+5V	+12V
LLT
1
2
3
4
5
CL1
CL2

Oh yeah, we have some improvement here, too. All three outputs have less ripple than the older version gave us. Not by much, mind you.

The older version, at 12V, actually had less ripple than this one, technically. But it blew that all to hell by having a bunch of these smooth up and down peaks and dips which totally negates that advantage. This unit is more of a straight 25mV line, which is preferable to me.

Meantime, the minor rails are both doing better on the new guy. We have 20mV vs. 25mV for the 5V rail and 15mV vs. 20mV. I can live with that. To be clear, both units have excellent performance in this regard. It’s just that the new one is slightly more excellent.

So… the new one improves on efficiency and ripple control at the cost of some stability. Let’s pop the hood and see what’s underneath.