In May, Antec sent us the 850W version of their Signature series, which delivered quite an impressive performance. They now have a smaller 650W model, and we wanted to test it and see how it compares to its "big brother". The appearance and feature set of the two models are similar, with the only difference being the rated wattage and price. We'll also discuss how it compares with competing power supplies from other manufacturers.

With the Signature series, Antec delivered with the first PWM-controlled fan, which they of course immediately patented. Antec wants to use this control unit to allow for better tuning of fan speeds and promises up to 50% quieter performance -- though we have to ask, 50% compared to what? Enermax utilizes a similar technology in their new Pro82+ and Modu82+ power supplies, which resulted in very low acoustic noise when we tested them. In addition, Antec already runs these power supplies with VRMs to generate the 3.3V and 5V rails instead of the old-fashioned transformer approach. We have seen Silverstone and Enermax follow that trend, and soon Seasonic will join them, as this technology brings a lot of benefits. For example, you get not only short transient response times but also better efficiency from the generated voltages.

The specifications show a minimum load on all rails, which is a no-load operation feature. This means that the PSU can run without any component attached to it. Normally power supplies have problems if you run it without a load attached, i.e. if you were to only connect a hard drive. The 3.3V and 5V rails both deliver up to 24A for a combined power of 140W, which is more than sufficient. There are three 12V rails, with 22A for the first two rails and 25A for 12V3. All of these rails have a combined power of 634W plus the -12V and standby 5V rails.

Packaging and Appearance


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  • HOOfan 1 - Thursday, October 2, 2008 - link

    There is really no comparison at all, other than they are both Antec, both made by Delta, and both rated at 650W. Beyond that not much to compare, the Signature is a server grade PSU, the Earthwatts is a very decent value line PSU.

    1) The Signature is Modular (that costs money right there)

    2) The Signature has all fully sleeved cables (costs money)

    3) The Signature has a PWM controlled fan (costs money)

    4) The Signature's Voltage regulation is within 1% while the EA650 is only as good as 3%

    5) The Signature is as much as 3%-4% more efficient than the EA650

    6) Kris thought the ripple suppression was unimpressive for the Signature (really that is pretty weird) well the EA650 has 70mV ripple on the 12V rails as opposed to less than 9mV on the Signature

    7) Last but certainly not least the Signature is good for 94W more power on the 12V rails than the EA650.

    The EA650 is for people who want a decent quality unit for a great price, the Signature 650W is for people who want a rock solid, stable PSU and don't care how much they pay for it.
  • bob4432 - Thursday, October 2, 2008 - link

    where did you find this info? i have been looking for a ea650 review for over a month now and never came up w/ you have a link to a full review? Reply
  • HOOfan 1 - Friday, October 3, 2008 - link

    well I am not sure how much anandtech would appreciate me linking to another review, but their sister site Dailytech does it all the time, so here you go">Oklahoma Wolf's review of the EA650 at
  • bob4432 - Friday, October 3, 2008 - link

    thanks for the link. i had even asked on jonnyguru's site in the past for a review, so now i get to read it :) Reply
  • steveyballme - Wednesday, October 1, 2008 - link

    This is some solid hardware!">
  • dwvcore - Wednesday, October 1, 2008 - link

    Antec makes some nice power supplies (I have used them many a times before), but they are not competitive with their prices at all ! Their Basiq and Earthwatts Series are O.K., but as soon as you step up to their signature or neo-watt series it skyrockets. An Antec 650 Signature costs $200, while you can get a 650w Corsair PSU for about $110 (newegg). Reply
  • JEDIYoda - Thursday, October 2, 2008 - link

    Well if monmey is a factor then get the Corsair.
    The Antec Signature Series is supposedly the new standard by which all others are tested! -- according some knowledgeable reviewers
  • MamiyaOtaru - Wednesday, October 1, 2008 - link

    No way in heck I am using anything smaller than a 120mm fan in my computers. Yes, that includes on the GPU, and yes that means I don't use the stock coolers. But I'm sure as heck not going for a PSU with a smaller fan. There aren't a lot of aftermarket PSU coolers out there that would let me replace the fan with a larger one. Reply
  • Goty - Wednesday, October 1, 2008 - link

    I don't understand the stigma about smaller fans in PSUs. If the unit is designed well, you can use a smaller fan and get noise and cooling levels equal to that of a unit that uses a larger fan. Reply
  • erple2 - Wednesday, October 1, 2008 - link

    I agree. What's the problem with a smaller fan? I think the problem is people are taking "rules of thumb" and applying them improperly. My computer chews through ~300W of power at peak loads (8800GTX, E6750, measured via my admittedly probably inaccurate UPS), and my (wasted extra) 750W power supply (PCP&C 750W Silencer) is essentially silent the whole time, with an 80mm fan. In fact, given my case design (PSU on the bottom), one of the 120mm fans would be worse for airflow than the 80mm fan I have now.

    I think the problem is people don't understand just how much power their computers require, and thus what loading their PSU's operate under. That dictates how much "noise" their 80mm vs. 120mm fans will generate.

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