Signature 650 PSU: Antec's Challenge

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Oct 30, 2008 by Mike Chin

Antec Signature 650
650W computer power supply
Antec Inc.
Market Price

Antec is one of the longest estabilished brands for retail packaged power supplies. In the early days, the company's primary business was in retail PC cases, and they probably got into power supplies in order to provide a more complete package for their case buyers. Antec has since grown into the most successful case brand in the retail market, and they also do a booming trade in power supplies.

While the company does much of its own design, manufacturing is subcontracted to a number of partners. For power supplies, Antec used Channel-Well for a long time, then expanded their suppliers in the last few years to include Seasonic, FSP and Enhance. Now, they've partnered with Delta Electronics, possibly the world's biggest maker of electronic power supplies. Delta products in the US and Canada seem to be limited to fans and generic OEM power supplies, but the company is highly regarded in its industry, and it has the capability to design and make just about anything in power electronics. The Signature series models, the 650 and the 850, are the first fruits of the new partnership.

The selling prices suggested by Antec make it plain that these products are intended for the very high end market: $250 for a 650W PSU and $300 for 850W give these models the highest dollar-per-watt ratio of any computer PSU out there. Admittedly, the street prices have dropped substantially since the products were released a few months ago. At time of posting this article, Newegg in the U.S. currently sells the 650W model for $160, and the 850W model for $199. These prices are still on the high side for the power rating, but let's make a full assessment of what's being offered for the money.


The elaborate packaging of the Antec Signature power supplies is reminiscent of other luxury consumer products, such as an expensive bottle of 30-year old single-malt Scotch or a jewel-studded chalice fit for a prince, not a PC component that will become invisible as soon as it is installed. We find such packaging wasteful and unecological, but we also know that it can sell more products and establish stronger brand image... and that's what the consumer trade is still all about.

A classy looking sleeve over a retail box that could fit a pair of small boots. The box itself is made of stiff, heavy cardboard that small children (and bigger, older ones) will immediately claim to store their favorite small playthings and keepsakes.

Aside from a handy manual and a signed individual QC report for the particular sample (with serial number), which are standard, a reviewer's guide was also provided, on paper and on a CD. The CD contents were a PDF copy of the guide plus a few glamour photos.

The box split in two, with detachable cables, AC cord and mounting screws below.

SIGNATURE 650 FEATURE HIGHLIGHTS (from the product web page)
FEATURE & BRIEF Our comment
Voltage Regulator Modules for 3.3V and 5V lines

DC-to-DC conversion from the main 12VDC line eliminates the usual additional transformers for higher efficiency and transient response.
80mm Fan with Pulse Width Modulation (PWM) control PWM is more efficient, and in theory, allows the fan to run at very slow speed without risk of stalling, unlike straight voltage control. PWM often causes buzziness, however. The 80mm fan design is usually more efficient for cooling due to its straight-through airflow path compared to the right angle path 120mm fan PSUs.
Japanese made components Specifically, the fan and capacitors. Japan is upheld as a higher quality component producer.
Dual double PCB layout The circuit is spread out on two printed circuit boards. How? Later photos will show you. Should improve airflow and cooling. They claim the use of heavier components as well, though it's not clear exactly how that benefits... until after the unit is opened up and examined.
80 PLUS Bronze 82% or higher efficiency at 20%, 50%, and 100% load.
SLI Certification nVidia has checked and found it good for running two of its video cards in tandem. They specify limits, however: Cards no more powerful than 7900 GTX or Dual GeForce 7800 GTX 512MB
Hybrid Advanced Cable Management The mandatory cables are hardwired to reduce resistance, while the peripheral cables can be installed as needed... but this is the norm for modular cables, isn't it?
Safety: UL/CUL, TUV, CE, CB, CCC, FCC Class B, C-Tick Pretty standard.
Industrial grade protection circuitry prevents damage resulting 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 market.
MTBF: 100K Hours Min at Max. Load 230VAC, 25°C Ambient Conditions
Very good.
Antec's Quality 5 year warranty Very good!
Net Weight: 5.82 lbs
Gross Weight: 10.3 lbs
Size: 3.4"(H) x 5.9"(W) x 7.1"(D)
Good to know.



The label on the PSU usually tells us most of what we need to know, but not all.

The product web page, surprisingly, did not appear to have complete specifications. The first table below is from the manual, which confirms the label; the second is from the reviewer's guide. The manual's power output details are more complete and correct: The total current for the 12V line is given as 53A in the reviewer's guide and on the web site. This much current would be available on the 12V line only if the other lines were delivering less than 14W (since the maximum rating is 650W). The manual states more completely that 43A is available on the 12V line when the maximum total of 140W is drawn from the 3.3V and 5V lines. In an case, the reader should be aware that total 12V power capability for any ATX12V PSU is not a fixed number, but can vary depending on many conditions, including load on the other lines, and operating temperature.

Scanned from the manual.

From the reviewer's guide.

Three 12V lines: Note that three 12V lines are indicated. This usually means there are three separated paths for the 12VDC from the transformer/rectifier to the outputs. Each of these paths has a limiter on it to keep the current from exceeding the stated maximum. A user who seeks the maximum current from this PSU would want to know which outputs correspond to which 12V lines; this would allow the 12V load to be distributed evenly. Usually, this info is not provided, but Antec has done the smart thing and marked the modular output connectors as 12V1 or 12V3. However, whether all the attached cables are feeding off 12V2 (not likely) or a combination of the three 12V lines is not clear. Too bad that Antec didn't go all the way and tag or identify the 12V line for every output cable.

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