X-650: Seasonic hits Gold

Viewing page 1 of 6 pages. 1 2 3 4 5 6 Next
X650 650W (SS-650KM) computer power supply
Sample Supplier
Seasonic USA
Seasonic Electronics
Suggested Price

In the four years since its inception, 80 Plus has successfully become a major benchmark for computer power supplies. It was ostensibly a program to reduce electricity demand, sponsored by a consortium of power utilities in the US, and aimed initially to promote higher AC/DC conversion efficiency in computer power supplies. The first target was 80% conversion efficiency; hence the name of the program. Since then, 80 Plus has been widely accepted by the industry, and the original single 80% category was expanded to reflect higher goals: Bronze, Silver and Gold. The highest category, Gold, calls for 90% efficiency at 50% of rated load, at 87% at 20% load and 100% load. With the massive proliferation of PSU brands in the past few years, efficiency and 80 Plus approval became an important marketing differentiator, with money and energy savings as well as eco-friendliness the oft-mentioned benefits.

Seasonic has been a primary innovation leader in computer power supply design and manufacturing over the past decade, and a pioneer in high energy efficiency. Seasonic-made PSUs have also dominated the top ranks of SPCR's Recommended PSU list for years (under its own brand and under the brands of its clients, such as Antec and Corsair). All the way back in October 2008, Seasonic became one of the first to achieve the Gold 80 Plus award for its then upcoming 550LT, 650KM and 750KM models. The 650KM model under review here is one of the first 80 Plus Gold PSUs available on the market in North America.

The X-Series is a logical followup to the M12D series released last year. The M12D achieved 80 Plus Silver rating, with assured 85% minimum efficiency at all power levels. The M12D-850 we reviewed last December remains at the top of our recommended power supplies. It's interesting to note that the X-Series does not include any "super power" models thus far.

As with the M12D-850W review sample, Seasonic included a few extras in the reviewer's package: A small auxiliary PCB which contains the DC-to-DC converter, a reviewer's guide and other technical documentation on an optical disc.


The gold-black retail box is bigger than most others from Seasonic in the past, except for the M12D series.

The back of the box is packed with technical promotional details.

Seasonic X-650 FEATURE HIGHLIGHTS (from the web product page)
FEATURE & BRIEF Our comment
Core Features
80PLUS Gold Certified Super High Efficiency Assured 90% power conversion efficiency.
DC to DC Converter Design; Patented DC Connector Module with Integrated VRM [Voltage Regulator Module]
DC-to-DC conversion for the lower voltage lines is not unusual, but Seasonic's implementation is unique.
Patented Hybrid Silent Fan Control The fan does not spin at low loads, making it silent. Hybrid suggests a cross between passive and active cooling.
Sanyo Denki San Ace PWM Silent Fan

Presumably a variant of the superb fan used in the M12D. PWM speed control probably makes semi-passive operation practical.

"Green Innovation" Features for Extended Product Life, High Quality, High Efficiency, and Competitive pricing
High Reliable 105°C Japanese Capacitors

Many high end PSUs flaunt this feature, including Seasonic's own M12D series.

Conductive Polymer Aluminum Solid Capacitors These advanced caps are also used on motherboard.
Super High Efficiency [up to 90%]
Green solution for lowering energy consumption, noise & heat.
Dual Sided PCB Layout
Better utilization of PCB space to enhance quality and performance.
Tight Voltage Regulation [±3%] More stringent than the ±5% recommended by the Intel ATX12V PSU design guide.
Ample +12V Output
54A (648W) on a single rail. We've come full circle from the madness of multiple 12V lines so popular a few years ago.
Safety: UL/CUL, TUV, CE, CB, CCC, FCC Class B, C-Tick, GOST-R, UkrTEST, BSMI, Semko Very good.
Protection from short circuits (SCP), over voltages (OVP), over power (OPP), over temperature (OTP), and over current (OCP) The more the merrier.
Universal Input, Active PFC Like just about every PSU on the retail market... but Seasonic was the pioneer with these features on computer PSUs.
MTBF: Over 150,000 hours at 25 Deg C. excluding the DC Fan.
Very good.
Seasonic 5 year warranty Very good!
Net Weight: 5.82 lbs (w/o cables)
Size: W150 x L160 x H86 mm
Slightly longer than normal.


The most complete specifications are found in the manual.

Seasonic SS-650KM Specifications
AC Input
90~264VAC 8~4A 50/60 Hz
DC Output
Operating Temp: 0~50°C, 100% Continuous Power @ 50°C

Unlike the M12D-850W which is not assured to provide full output power above 40°C, X-650 is spec'd to provide 100% rated power to 50°C. This spec is more typical of server class PSUs than desktop PSUs.

Keep in mind that the testing for 80 Plus approval is done at normal ambient room temperature. The 80 Plus Testing Guidelines (PDF) specify only that "ambient temperature shall be maintained at 23°C ± 5°C throughout the test." In contrast, the ambient temperature of the SPCR test system is directly proportionate to the load. At low load, the air intake is at or just above room temperature, but as load is increased, the temperature rises steadily. Typically, with a fan-cooled PSU, the intake temperature in our test system reaches 45~50°C at >600W loads. This is an extremely tough test condition, as PSU efficiency naturally drops off at high and low loads; combine high load with high temperature and it's essentially a torture chamber. It does replicate reasonably well the conditions that prevail in a typical tower PC. For full details, please refer to SPCR's PSU Test Platform V4.1.

1 2 3 4 5 6 Next

Power - Article Index
Help support this site, buy the Seasonic X650 650W Power Supply from one of our affiliate retailers!