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Seasonic X-Series 660W Power Supply Review

Rating: 9.0.

Over the last couple of months we have looked at the excellent X-Series 850W and 1250W power supplies – they both earned our highest awards. Today we look at the more affordable 660W version, a modular design which has achieved 80 Plus Gold Certification. This range of power supplies has proven popular with the enthusiast audience as they are a ‘no-compromise’ design incorporating high grade Japanese capacitors and class leading standards of build quality.

In a similar fashion to the other models we have reviewed, the 660W version adopts a “Hybrid Silent Fan Control” design, which offers three distinct operation modes, fanless mode, silent mode, and cooling mode. The X Series automatically adjusts fan mode and speed according to the ambient temperature level. This brand new design not only optimizes heat dissipation, but also prolongs lifespan of the system by reducing unnecessary fan rotation.

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 X-Series box artwork is identical to the other versions, with the wattage output listed top right.

The power supply is protected between thick foam pads with the accessories stored on the right side of the box. The user manual rests on top.

The bundle includes a fancy dual compartment pouch storage bag for the cables, a regional specific power cable, cable ties (plastic and felt) and case badge.

The modular bag contains all the cables, and can be resealed to store unneeded cables. The quality of the cabling is top class, and are all sleeved. There are four PCI-E 8/6 pin cables – 600mm in length which will support Crossfire and SLI system configurations.

The Seasonic X Series 660W power supply ships with a paper wrap around it explaining that the fan will be inactive at less than 20% load.

The unit itself is very attractive, nicely finished, yet understated to suit a variety of windows case systems. The paintwork is deep and will withstand rough handling over time.

The 120mm fan is hidden behind a black grill without Seasonic labeling visible.

One side of the power supply is fully vented to improve air flow. At the side is a power switch and connector.

The X-Series 660W has several rows of connectors available for the modular cabling. These are all labeled for ease of installation. There is a ‘Temperature Activated Fan – Rotates only when required’ sticker bottom right.

Seasonic X-Series 660W Power Supply
DC Output
+3.3V
+5V
+12V
-12V
+5Vsb
Max Output
25A
25A
54A
0.5A
3A
Total Power 125W 648W 6W 15W
660W

54A can be delivered to the +12V rail, adequate power on tap for demanding gaming systems.

Seasonic are using a high grade Sanyo Denki San Ace fan – the same model is installed in the 850W version of the unit (9S1212F404). This fan uses dual ball bearings to enhance life span and reliability. It is constructed around 7 blades which are sculpted to reduce noise while maintaining a high level of airflow.

This supply uses only a couple of heatsinks, however with the 80 Plus Gold Efficiency rating and the large fan overhead it should be fine.

As we noted before, Seasonic are not skimping on the quality of the components in this system. Japanese capacitors are used throughout, with the primary stage using two Nippon Chemi Con caps, rated 420v 330 uF @ 105c.

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
• SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa)
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

We are combining 12V output into a single result.

DC Output Load Regulation

Combined

DC Load

+3.3V
+5V
+12V
+5VSB
-12V
A
V
A
V
A
V
A
V
A V
152W
2.04
3.32
2.05
5.03
10.12
12.11
0.50
5.03
0.20
-12.02
270W
3.02
3.32
3.01
5.02
19.12
12.10
0.50
5.03
0.30
-12.03
400W
4.04
3.31
5.05
5.00
29.19
12.07
1.00
5.02
0.30
-12.05
523W
6.05
3.30
7.03
5.00
38.17
12.04
1.50
5.01
0.30
-12.08
652W
8.05
3.28
9.03
4.99
48.01
12.00
2.50
5.00
0.30
-12.10

Voltage regulation scores in the top 5% of results, maintaining well across all output stages.

Seasonic X-Series 660W Maximum Load
807.4W

The power supply delivered 807W before it would shut down safely – Seasonic are clearly over specifying these units as they all produce significantly more power than their rated output. While not recommended long term, this power supply can hold 800W without any issues for quite some time.

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
590W 1.0 3.32 1.0 5.02 48.0 11.99 0.2 -12.03 0.50 5.02
145W 12.0 3.28 15.0 4.98 2.0 12.10 0.2 -12.01 0.50 5.01

The Seasonic X-Series 660W exhibited no problems when dealing with this intensive set of Cross loading figures. It was hit with 48A on the +12V rail and held at close to 12.00V. The other rails also delivered remarkable results.

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
152W 5 5 15 10
270W 5 5 20 10
400W 10 10 20 15
523W 10 15 25 15
652W 15 15 30 15

Noise suppression is excellent, peaking at 30mV on the +12V rail under full load. The other rails peak at 15mV at full load. These results are well within rated industry tolerance ratings.

Efficiency (%)
152W
84.03
270W
91.24
400W
91.01
523W
89.67
652W
88.81

Efficiency is very good, peaking over 91 percent at 50 percent load. At full load this drops to just below 89 percent.

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 Refridgerator
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)
152W
<28.0
270W
29.3
400W
30.6
523W
32.7
652W 33.2

Generally this power supply is completely inaudible, especially when the system is resting idle. Even at 50% load, it can barely be heard and is likely to be drown out with chassis fans. Above 500W load, the fan spins up fairly actively, although noise levels are still low. At full load, the fan is audible, but not intrusive.

Temperature (c)
Intake
Exhaust
152W
36
38
270W
37
41
400W
38
45
523W
42
47
652W
44
51

The large fan is perfectly capable of maintaining a very good thermal curve, peaking at only +7c above ambient threshold at full load.

Maximum load
Efficiency
807.4W
86.12

Pushing the PSU above its rated limits generates an ultimate efficiency level of around 86.5%. This is not a viable ‘real world’ situation, but its interesting nonetheless.

We haven’t been disappointed with the Seasonic X-Series 660W power supply, it is just as impressive as the higher output units which we have reviewed over the previous couple of months. A 660W unit will obviously sell more units than a 850W or 1250W unit due to the lower price point.

The X Series 660W is an attractive power supply, finished with deep black paint which proves resilient to scratching. It does attract finger prints, although they are easily removed with a cloth.

Impressively, Seasonic are clearly over specifying these units, as this unit was able to hold a 800W output without issue. Not often we see a unit holding a 150W above rated power level for a long period of time.

Technically there are no weaknesses with this design. It delivers high levels of efficiency while maintaining strong noise suppression. The +12V output peaks at 30mV under full load and +3.3V/+5V peak at 15 mV under the same conditions.

At the lower end of power delivery the fan doesn’t spin at all, ideal for people who are running a media center in a living room or bedroom. Even when tasked above 500W when the fan spins up, it never becomes intrusive. Seasonic have opted for an expensive Sanyo Denki San Ace fan which is designed for long life and quiet operation.

The modular design is very impressive and will suit a wide audience who don’t want to have to route a plethora of unnecessary cables. The dual pouch storage pouch is a worthy addition and ensures no cables will be lost over time.

We have no hesitation recommending this power supply, and like the others in the X-Series range it is built to the highest standards. This is an ideal choice for a gaming system or high grade media center when partnered with more demanding components.

Just before we published this article, Seasonic instructed us that this X-Series 660W unit is now discontinued. That said, there will be stock of this unit in the channel, so the results are still useful. The company are updating this range with a new 650W model which Kitguru will be reviewing as soon as possible.

Pros:

  • Excellent build quality.
  • Modular design.
  • quiet, quality fan.
  • efficient.
  • stable load regulation.
  • can deliver over 1,000Watts!

Cons:

  • There is a price premium with this design.

Kitguru says: No weaknesses in this X-Series range. The 660W joins the X-Series 850W and 1250W as another ‘must have’ design.

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