Seasonic X-Series 1250W Power Supply Review

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 (Super High Gallery)6. Testing Methodology & Results7. Closing Thoughts8. View All Pages

Seasonic really need no introduction, they have been the OEM behind some of the world's finest power supplies for many years. Today we are looking at the X-Series 1250W unit, a fully modular design which has achieved 80 Plus Gold Certification.

Seasonic haven't cut any corners, they are using the highest grade 105c Japanese capacitors and are focusing on maintaining low noise levels.

The unit adopts a Hybrid fan control system which is an advanced 3 phased (Fanless, Silent and Cooling Mode) thermal control system, to offer a balance between silence and cooling.

Hang on, does this sound familiar?

If you are a regular reader of Kitguru, you may remember our review of the XFX Pro 1250w Black Edition last November. XFX used the Seasonic design for their power supply with some noticeable, cosmetic differences.

When Hybrid mode is enabled the power supply will operate silently until it reaches 20% load, or 25c. After 20% load (or internal temperatures of 25c) the fan will ramp up, pre-configured to ‘quiet’ mode (rated at 16dBa). When 50% load is reached (625w) then the power supply will switch to ‘Cooling mode’ which is only rated at ‘greater than’ 16 dBa. We will look at this in detail, later in the review.

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.

Seasonic box artwork is subtle and understated in design. We like it.

The power supply ships underneath a user manual, protected underneath foam. The accessories are set to the right of the box.

The bundle includes a thick felt bag with the modular cables inside. A regional specific power cable and user manual is also included. Lastly, the company include a clear bag with plastic and felt cable tidies. There is also a case badge so you can broadcast to the world that your system is powered by Seasonic.

All of the modular cables are held inside a heavy duty felt bag which is split into two compartments. This can be reused and sealed, to store cables which you aren't using.

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 supply is very attractively designed, with deep black paint on all panels. The top of the chassis has a gold panel with a large fan underneath. The X-Series is fairly resistant to finger prints and minor scratches. It measures L190 x W150 x H86 mm.

The 120mm fan is hidden behind the grill, but we will take a closer look shortly when we take the unit apart.

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 as shown above – these are all clearly labelled to ensure even the most inexperienced user won't run into installation problems. There is a sticker on the chassis which highlights the dual switch operation – hybrid and normal. This sticker can be removed before use.

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). This is a high grade 120x120x38mm fan, which operates at 12V. XFX used a Protechnic Magic MGA13512YF fan in their version of this power supply.

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 super high resolution images of the product taken with the 24.5MP Nikon D3X camera and 24-70mm ED lens. 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 recently – 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
• Extech digital sound level meter
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
330W	5.52	3.38	5.51	5.04	21.26	12.20	0.87	5.02	0.20	-12.06
620W	11.01	3.36	11.02	5.03	42.51	12.14	1.75	5.00	0.40	-12.09
918W	16.51	3.34	16.52	5.01	63.72	12.13	2.60	4.99	0.60	-12.13
1249W	9.00	3.30	9.37	5.00	96.00	12.07	3.45	4.98	0.80	-12.14

Seasonic X-Series 1250W	Maximum Load
	1346W

We managed to squeeze 1346W out of the unit before it would shut down gracefully.

Cross Load Testing	+3.3V		+5V		+12V		-12V		+5VSB
	A	V	A	V	A	V	A	V	A	V
1190W	1.0	3.34	1.0	5.03	95.0	11.93	0.05	-12.12	0.05	5.01
195W	22.0	3.31	22.0	5.00	1.0	12.14	0.05	-12.11	0.05	5.00

An excellent set of results, highlighting that the design can handle dramatic load changes without any concerns at all. There is a slight dip when quickly loaded with 95A on the +12V, but it isn’t anything which would cause a problem.

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
330W	10	15	15	15
620W	15	20	25	15
918W	15	25	30	20
1249W	15	25	45	20

As we had hoped from the Seasonic design, noise suppression is very good, with the 12v output peaking at 45 mV at full load. All are well within industry tolerance guidelines.

Efficiency (%)
330W	89.47
620W	91.94
918W	90.47
1204W	89.78

Efficiency results are impressive, peaking around 92% at 50 percent load. This falls to just below 90 percent at full load.

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 Digital Sound Level Noise Decibel Meter Style 2 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)
330W	28.0
620W	28.0
918W	30.5
1249W	33.8

Accurately reading noise emissions below 28 dBa is difficult without strict laboratory conditions. The unit rated right at the limits of our testing equipment at 28 dBa when at 50 percent load or less. When it is primed to around 900W it becomes audible. These results are very similar when compared against the Protechnic Magic MGA13512YF inside the XFX Pro 1250W Black Edition power supply.

Temperature (c)
	Intake	Exhaust
330W	37	40
620W	39	44
918W	44	52
1249W	47	57

Thanks to the high levels of efficiency, the exhaust temperatures are really good, rising to a 10c above ambient under full load.

Maximum load	Efficiency
1346W	87.79%

For those interested, we measured the efficiency when stressing the unit to breaking point … around 87.79% at 1346W.

The Seasonic X-Series 1250W power supply really is a great design, our view on it hasn't changed since we reviewed the XFX Pro 1250W Black Edition last November. The overall design is rock solid, well built and exhibits no discernible weaknesses.

This year it faces some serious competition however from new 80 Plus Platinum certified products – such as the Corsair Professional Series AX1200i.

We also rate the BeQuiet! Dark Power Pro 10 1200W highly, another top award winner on Kitguru, and another Seasonic OEM design.

Technically, the DC to DC Seasonic design is exemplary, combining very high levels of efficiency with rock solid voltage regulation. We cross loaded the power supply quickly with 95A on the +12V output and it held steady, only dipping a little to 11.93V. A lesser design would find this a real problem to handle and we have even experienced several failures with other units when pushing this hard.

Noise suppression is decent and none of the results cause concern and are well within rated industry tolerance levels. +12V peaks at 45mV and the +3.3V and +5V ripple results were just as positive, peaking at 15 mV and 25 mV respectively.

As always, we put the Seasonic X-Series 1250W through some ‘real world' paces. We used it in a system with a liquid cooled Core i7 3960x Extreme Edition processor overclocked to 4.8ghz, paired up with 32GB of ram, and two Nvidia GTX590′s in Quad Sli.

The total system drain was 930 Watts at the socket and this power supply handled the load without a hitch, or by generating high levels of noise from an overactive fan. Generally the power supply is basically silent, unless pushed very hard (1000 watts+ and it becomes audible).

In the United Kingdom, you can pick up the Seasonic X-Series 1250W for £213 from ARIA, having just received some aggressive price reductions today. If you want an 80 Plus Platinum Certified unit close to the same capacity, and don't mind spending extra, then we can also recommend the Corsair Professional Series AX1200i, although at £262.94 inc vat, it is very expensive.

Pros:

• Quiet.
• Immensely powerful.
• Fabulous appearance.
• very efficient.
• Fully modular.
• rock solid.
• Recent price drops.
• 8 PCI-E 6+2 cables for ultimate Crossfire and SLI system builds.

Cons:

• None.

Kitguru says: Another award winner for XFX. A class leading Seasonic design. Rock Solid.

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