Seasonic X-Series 650W KM3 Power Supply Review

1. Introduction2. Seasonic X-Series 650W KM3 (Bundle & Cables)3. Seasonic X-Series 650W KM3 (External)4. Seasonic X-Series 650W KM3 (Internal)5. Seasonic X-Series 650W KM3 (Super High Res Gallery)6. Testing Methodology & Results7. Closing Thoughts8. View All Pages

Seasonic really need no introduction, they have been releasing multiple series of class leading power supplies in 2012. They recently launched the latest X-Series KM3 range, superseding the award winning KM2 units which we reviewed last year. Today we are looking at the X-Series KM3 650W power supply, a very popular wattage capacity with the enthusiast audience.

The X-Series 650W KM3 is not just a simple refresh however as the internal design has been changed and we will take a look at this later in the review. The KM2 was already a very impressive unit, so we are interested to see just how far further the company can push the new design.

They have three models already in the KM3 range, a 650W, 750W and 850W model all with a single +12V rail, fan controller and new modular cabling.

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 [±1%]
• 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]
• 7 Years Warranty

Seasonic changed their box artwork when they introduced the KM3 range, although the concept idea is still the same. Seasonic always produce very subtle, understated artwork which we like.

The X-Series 650W KM3 is well protected between thick foam and is wrapped inside a felt bag for further protection. It would be difficult to damage this product during transit.

The bundle includes cable ties, a user manual, a regional specific power cable and a felt bag with two pouches. The modular cabling is stored in these.

Seasonic have changed their cabling, which we noticed when we tested the 850W KM3 in December last year. The adoption of flat ‘ribbon' style cables will please a large audience as they are better for air circulation. The company are still using high grade 18 AWG cables.

This power supply ships with four 6+2 pin PCI E cables, ideal for dual card Crossfire or SLI systems. The 20+4 pin ATX connector and 4+4 pin EPS/ATX12V cables are 650mm long.

The Seasonic X-Series 650W KM3 is nicely finished with thick paint resistant against rough handling. As with the 850W KM3, the unit passed our screwdriver stress test – we run the head down the side of the chassis with a little force. It didn't mark.

The unit measures 160mm x 150mm x 86 mm (LxWxH). It will fit into any mainstream ATX compliant chassis.

The large fan is hidden behind a black honeycomb grill. We will look at the fan in more detail when we crack open the chassis later in the review.

One side of the power supply is vented which helps enhance air flow. There is also a power switch and connector at the side. The Seasonic badge is seen underneath the power port/switch.

The KM3 modular panel has changed completely over the last revision. There is now a ‘hybrid’ fan switch which you can toggle on or off – the blue sticker alerts you to this initially and should be removed before using the supply. Seasonic have said this is the industries first ‘advanced three phased thermal control’.

The Hybrid Silent Fan Control provides three operational stages:  Fanless, Silent, and Cooling Mode. In addition, there is a switch provided to allow for manual selection between the Seasonic S2FC (fan control without Fanless Mode) and the S3FC (fan control including Fanless Mode).

Seasonic X-Series 650W Power Supply (KM3)
DC Output	+3.3V	+5V	+12V	-12V	+5Vsb
Max Output	25A	25A	54A	0.5A	3A
Total Power	125W		648W	6W	15W
	650W

54A can be delivered to the +12V rail, which is plenty for two relatively high end graphics cards.

Seasonic are using a very high grade 120mm Sanyo Denki San Ace fan (9S1212F404) – the same fan they are using in the 850W KM3. 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 same model was also incorporated into the KM2 supply. We have no complaints as this is genuinely one of the best fans that money can buy.

The internal build and soldering quality is as good as we have seen. A stellar job by Seasonic.

Behind a metal shield is the AC receptacle unit. There are two Y caps, an X cap and a coil here. There is more transient filtering on the main PCB, two X caps, two Y caps, two coils and a TVS diode.

The VRM from both sides. They are using the APW7159 controller.

There are two Bridge Rectifiers in this unit – marked GBJ1506. The PFC Section has two MOSFET's and a single diode.

Seasonic are using Hitachi electrolytic capacitors and Nippon Chemi-Con capacitors on the primary and secondary stages respectively.

The outputs of the unit are monitored by an integrated circuit which supports over voltage, under voltage and over current protection. There are four OCP channels, two for +12V, one for +5V and another for +3.3V.

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

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
152W	2.03	3.33	2.04	5.04	10.12	12.06	0.50	5.03	0.20	-12.03
270W	3.02	3.33	3.05	5.04	19.14	12.05	0.50	5.03	0.30	-12.03
400W	4.05	3.32	5.00	5.03	29.17	12.04	1.00	5.03	0.30	-12.03
523W	6.08	3.32	7.04	5.03	38.19	12.02	1.50	5.02	0.30	-12.04
650W	8.00	3.32	9.00	5.02	48.00	12.01	2.50	5.01	0.30	-12.04

Voltage regulation is class leading, with hardly any fluctuation at all, even when loaded to maximum. As good as we have seen in the last 14 months.

Seasonic X-Series 650W KM3	Maximum Load
	812W

The power supply would shut down at 812W, gracefully. The protection circuitry worked well.

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	3.33	1.0	5.04	48.0	12.01	0.2	-12.02	0.50	5.00
145W	12.0	3.31	15.0	5.02	2.0	12.05	0.2	-12.03	0.50	5.01

Cross load results are class leading. All rails held close to nominal values, regardless of the demand.

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	10	5	15	10
270W	10	10	20	15
400W	15	10	25	15
523W	15	15	25	15
650W	15	20	30	15

Ripple suppression is great, with the +3.3V output peaking at 15mW. The +5V output peaks at 20mV. +12V output peaks at 30 mV. All of these are well within tolerance guideline specifications. Excellent results.

Efficiency (%)
152W	85.31
270W	88.45
400W	92.03
523W	91.37
650W	89.21

Efficiency is exceptionally strong, peaking around 92 percent at 50 percent load. At full load this drops to just over 89 percent efficiency.

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	<28.0
400W	29.1
523W	30.4
650W	32.8

This power supply is extremely quiet, even quieter than the 850W in the last 20 percent of load. When delivering 650W of power it is barely audible and registers just under 33 dBa on our sound meter.

Temperature (c)
	Intake	Exhaust
152W	36	39
270W	39	44
400W	42	48
523W	45	52
650W	47	57

The internal temperatures are very impressive, rising to an 10c above ambient threshold when placed under full load.

Maximum load	Efficiency
812W	86.3

Pushing the PSU above its rated limits generates an ultimate efficiency level of around 86.3%. This is not a viable ‘real world’ situation, but its interesting nonetheless.

The Seasonic X-Series 650W KM3, like the 850W KM3 is right at the top of its respective class. No power supply is perfect, but the KM3 series exhibit no weaknesses and deliver stable, high quality power to the system.

Load regulation is class leading and there is no 650W supply we have tested as capable as the 650W KM3 in this regard. Our intensive cross loading test didn't cause a problem for the unit with it delivering almost nominal results. Ripple suppression is excellent with the unit peaking well within specifications for +3.3V, +5.5V and +12V output.

The addition of a new fan S2FC/S3FC selector switch and flat ribbon style modular cabling just enhances the overall appeal to the extremely demanding enthusiast audience.

For those people looking to reduce system noise emissions then this deserves serious consideration. At a 500W power demand the fan was only spinning at a slow to moderate rate and was barely audible. Most gaming systems today will not even be demanding close to 500W power under load.

The X-Series 650W KM3 will also be a practical choice for a high end media center. The passive fan profile means the system will not add noise to the overall build, only really becoming audible at 550W or above.

You can pick up the Seasonic X-Series 650W KM3 power supply for £114.98 inc vat from Overclockers UK. It is a fairly expensive unit, but if you want the finest power for your system, then this is certainly worth the money.

Pros:

• Load regulation is excellent.
• Ripple suppression is well within industry tolerance guidelines.
• extremely passive fan configuration – very low noise.
• 80 Plus Gold+ efficiency levels.
• can deliver over 800W of power before shutting down.
• Pure modular design.
• 105c rated capacitors.
• fan switch.

Cons:

• Expensive.

Kitguru says: Another quality, rock solid power supply from Seasonic.

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