Seasonic X-Series 1250W Power Supply (SS-1250XM2)

1. Introduction2. Seasonic X-Series 1250w (Bundle & Cables)3. Seasonic X-Series 1250W (External)4. Seasonic X-Series 1250W (Internal)5. Seasonic X-Series 1250W (High Res Gallery)6. Testing Methodology & Results7. Closing Thoughts8. View All Pages

Seasonic have had an active couple of months – in May we reviewed their Platinum 1,200W Modular PSU and today we are looking at the new X-Series 1250W – a refresh on the older model which we looked at, way back in 2012. The new model is a pure modular design with 80 Plus Gold Certification, but it has received a handful of upgrades since the original launch. Is it worth shortlisting for an upgrade in 2014?

The 2014 Seasonic X-Series 1,250 Watt power supply features an upgrade to the Hybrid Fan control circuit. It incorporates a new IC which controls the fan based on ‘Hysteresis'. It may be a confusing term for many, although we mentioned it in our review of the Seasonic Platinum 1200W model. For those interested this page on Wikipedia reads ‘Hysteresis is the dependence of the output of a system not only on its current input, but also on its history of past inputs. The dependence arises because the history affects the value of an internal state. To predict its future outputs, either its internal state or its history must be known.If a given input alternately increases and decreases, a typical mark of hysteresis is that the output forms a loop as in the figure.'

In layman's terms, the new Hysteresis IC controller will reduce the ‘on/off' cycle of the fan and further improve energy utilisation in Fanless and Silent modes.

The other major upgrade is the addition of a Dual Copper Conduction Bar on the PCB for optimised high current conduction – this will help enhance efficiency and performance.

Special Features –

• 80PLUS Gold Certified Super High Efficiency.
• Full Modular Cabling Design.
• Patented DC Connector Module with Integrated VRM [Voltage Regulator Module].
• DC to DC Converter Design.
• Seasonic Hybrid Silent Fan Control.
• Sanyo Denki San Ace Silent Fan.
• Conductive Polymer Aluminum Solid Capacitors.
• Highly Reliable 105℃ Japanese Brand Capacitors.
• Tight Voltage Regulation [±3%].
• Active Power Factor Correction [99% PF Typical].
• High +12V Output.
• High Current Gold Plated Terminals.
• Dual Sided PCB Layout.
• Ultra Ventilation [Honeycomb Structure].
• Multi-GPU Technologies Supported.
• All-in-One DC Cabling Design.
• Easy Swap Connector.
• Universal AC Input [Full Range].
• 5 Years Warranty.

The Seasonic box artwork hasn't changed in 2 years, although the subtle imagery and gold colouring still works well. Hopefully Seasonic will clear the old stock of the 2012 units in the retail channel, because it would be very difficult to work out which one you are buying.

The power supply is well protected between thick foam slabs, and is wrapped in a luxurious felt surround.

The box includes a thick felt bag with two separate pouches and the modular cables inside. A regional specific power cable is also included in the bundle. Seasonic bundle a clear bag with plastic and thicker felt cable ties. They also include a branded sticker, if you would like people to know you are using a Seasonic power supply inside the system.

Cables And Connectors:
(1) 24/20 Pin Main Power Connector
(1) 4/8 Pin ATX/12V/EPS12V Power Connector
(1) 8 Pin ATX/12V/EPS12V Power Connector
(8) 6/8 Pin PCI Express Connector
(2) 4 Pin Floppy Drive Power Connector
(8) 4 Pin Molex Peripheral Power Connector
(11) 15 Pin Serial ATA Connector

The cable quality is excellent, all fully sleeved and high grade 18AWG standard. They include 8 x PCI-E cables to ensure that even the most demanding SLI and Crossfire systems are supported.

The Seasonic X-Series 1250W power supply is nicely finished with gold accenting. Not so sure I like the appearance of the gold vented panel as much as I did in 2012, but this is very much personal taste. Seasonic have also changed the appearance of the side panels, but overall it looks very similar to the original 2012 model.

The fan is hidden behind the gold grill and we will take a closer look at this shortly when we open the unit.

One side of the power supply is fully vented to help with air flow. There is a power switch and connector at the side.

There are several rows of ports for the modular cables to be connected. These are all clearly labelled to help with the installation. There is a sticker on the chassis which highlights the dual switch operation – hybrid and normal. This sticker can be removed before use.

The new model is indicated by the new name ‘SS-1250XM2‘

Seasonic X-Series 1250W
DC Output	+5V	+3.3V	+12V	-12V	+5Vsb
Max Output	25A	25A	104A	0.5A	3A
Max Combined	150W		1248W	6W	15W

104A can be delivered to the +12V rail, which is more than enough for any system build.

Seasonic are using a San Ace 120 (Model 9s1212h403) fan (Sanyo Denki). This is a high grade 120x120x38mm model, which operates at 12V.

The Seasonic DC to DC convertor design is very clean with several rows of heatsinks separating the components. These may seem small, but with 80 Plus Gold Efficiency and the large overhead fan, there should be no ambient temperature problems.


The Seasonic X-Series 1250W power supply utilizes high quality Japanese capacitors throughout with the primary stage using three high quality Nippon Chemi Con capacitors rated for 105c operation @ 420v 390uF. We can also see the transient filtering with the Yunpen EMI filter. This continues to the main PCB with two coils, four Y capacitors, two X capacitors and an MOV.

The design of this unit replaces traditional wired connections with direct pin to port connections. This reduces the heat generated by the wiring which has the subsequent benefit of reducing lost power, ensuring improved voltage. The unit includes Total Power Protection (OPP), Over Voltage Protection (OVP), Over Current Protection (OCP), Short Circuit Protection (SCP), and Over Temperature Protection (OTP).
On this page we present some high resolution images of the product taken with a Fuji XT1 and a Sigma SD1 camera. These will take much longer to open due to the dimensions, especially on slower connections. If you use these pictures on another site or publication, please credit Kitguru.net as the owner/source.











Additional technical assistance: Peter McFarland and Jeremy Price.

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. Due to public requests we have changed our temperature settings – previously we rated with ambient temperatures at 25C, we have increased ambient temperatures by 10c (to 35c) in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:

• SunMoon SM-268
• CSI3710A Programmable DC load (+3.3V and +5V outputs)
• CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa)
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

We test the Seasonic Platinum 1200W power supply with the fan in the ‘normal’ state.

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
100W	1.55	3.38	1.75	5.03	6.65	12.17	0.50	5.01	0.20	-12.11
200W	3.13	3.37	3.50	5.02	13.50	12.17	1.00	5.01	0.20	-12.11
400W	6.40	3.36	7.05	5.02	27.50	12.16	1.50	5.01	0.30	-12.12
600W	9.80	3.35	10.77	5.01	41.70	12.15	2.00	4.99	0.30	-12.12
800W	13.25	3.35	14.55	5.01	56.40	12.12	2.50	4.98	0.50	-12.13
1000W	16.55	3.33	15.75	5.00	71.40	12.07	3.00	4.98	0.60	-12.13
1250W	9.02	3.32	9.41	5.00	96.00	12.07	3.45	4.97	0.80	-12.14

Load regulation is excellent with all the rails holding tight, within 2%.

Seasonic X-Series 1250W	Maximum Load
	1355W

We managed to squeeze 1355W out of the unit before it would shut down gracefully.

Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.

Cross Load Testing	+3.3V		+5V		+12V		-12V		+5VSB
	A	V	A	V	A	V	A	V	A	V
1190W	4.0	3.35	3.0	5.02	88.0	12.04	0.2	-12.11	0.50	5.00
240W	19.0	3.32	22.0	4.97	2.5	12.14	0.2	-12.09	0.50	5.01

The Seasonic X-Series 1250W power supply delivered a good set of results in the demanding Cross load test, as shown above.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum. ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Output	Ripple (mV p-p)
+3.3V	50
+5V	50
+12V1	120
+12V2	120
-12V	120
+5VSB	50

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load	+3.3V	+5V	+12V	5VSB
100W	10	15	15	10
200W	10	15	15	10
400W	10	15	25	15
600W	10	15	30	15
800W	15	15	35	15
1000W	15	20	40	20
1250W	15	20	40	20

Noise suppression is very good. All of the rails exhibit very low ripple and the +12v rail for instance peaks at 40mV, well within the rated specifications.

Efficiency (%)
100W	85.4
200W	88.6
400W	89.8
600W	92.0
800W	91.4
1000W	90.7
1250W	89.8

The overall efficiency results are excellent, peaking at 92% at 50% load. This drops to 90% efficiency at full load … a very impressive result.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the Power Supply we have taken it into our acoustics room environment and have set our SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa) one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide

10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refrigerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 Player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

Noise (dBA)
100W	28.0
200W	28.0
400W	28.0
600W	28.5
800W	31.2
1000W	33.2
1250W	34.1

The Seasonic X-Series 1250W power supply is basically silent until around 650-700W load is demanded and the fan starts spinning up at a faster cycle. At full load, the fan is clearly audible, although not that intrusive.

Temperature (c)
	Intake	Exhaust
100W	37	40
200W	37	44
400W	39	47
650W	41	49
800W	42	51
1000W	44	53
1250W	47	57

Temperatures are well controlled as the fan spins actively once load hits 1000W load and beyond.

Maximum load	Efficiency
1355W	88.0

Pushing the power supply above its rated limits generates an efficiency level of around 88.0%. This is not a viable ‘real world’ situation, but its interesting nonetheless.
There is no doubt that the Seasonic X-Series 1250W is a monster power supply designed to deal with expensive, high drain Crossfire and Sli system builds. This 2014 version builds on the strengths of the older model, tweaks the appearance a little and adds a couple of new features into the mix.

While the chassis has been redesigned a little, the new version looks very similar, with some artwork changes on the side panels. The fan controller has been upgraded with a new multi loop IC control incorporating Hysteresis to help prolong fan life. Dual copper bars are included with an reported extra 40% trace capacity which help it to handle higher current more efficiently.

Technically there is still little to fault with the core Seasonic design. It combines very high levels of efficiency with rock solid voltage regulation. It excelled with the intensive cross load test and handled a steady 96 amps via the +12V without a problem.

Ripple suppression is very good and +3.3V, +5V and +12V rails all fall well within the rated industry tolerance specifications. +12V peaks at 40mV and the +3.3V and +5V ripple results were just as positive, peaking at 15mV and 20mV respectively.

We tested the Seasonic X-Series 1250W with three Nvidia GTX Titan graphics cards, and a high end 4770k system, overclocked to 4.5ghz. It ran cool and stable showing the potential for ultra high end system builds. The pure modular design is also ideal for a high profile windowed system build – to help maintain a clean, tidy appearance.

You will be able to pick up the new SS-1250XM2 model in the United Kingdom very soon, at a price around £250 inc vat. This power supply deserves to be in the final shortlist for a new high end system build. It is an exceptional design and one that will cope extremely well with demanding graphics cards.

Discuss on our Facebook page, over HERE.

Pros:

• Quiet.
• rock solid.
• fully modular.
• Monster +12V output.
• built for demanding high end Crossfire and SLi systems.
• delivered 1350Watts+ before shutting down.

Cons:

• The gold coloured fan grill may not be to everyone's taste.

Kiguru says: Another top grade, high end power supply from Seasonic. Considering the feature list and immense power output, it is reasonably well priced.

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