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Seasonic Focus Plus Gold 850 PSU Review

EMC Pre-Compliance Testing

EMC, EMI & EMS Acronyms

Electromagnetic Compatibility (EMC): The ability of a device to operate properly in its environment without disrupting the operation of other close-by devices.

Electromagnetic Interference (EMI): This represents the electromagnetic energy a device emits, which can cause problems in other close-by devices if it is too high.

Electromagnetic Immunity (EMS): Tolerance to electromagnetic emissions.

Equipment & Standards

To properly measure the EMI that a device emits, you need special equipment defined by the CISPR 16-1-1 specification. To learn more about our EMI testing equipment, please check out How We Test Power Supply Units.

In order to minimize EMI noise, some standards have been established. The corresponding standards for Information Technology products are CISPR 22 and its derivative EN 55022. In the EU, every product featuring the "CE" marking has to comply with EN 55022. Both CISPR 22 and EN 55022 divide devices into two classes, A and B. B-class equipment is for domestic environments, so its allowed EMI emissions are significantly lower than for A-class devices.

CISPR / EN55022 Limits
CISRP 22/ EN 55022 Class A Conducted EMI Limit
Frequency of Emission (MHz)Conducted Limit (dBuV)
Quasi-peakAverage
0.15 - 0.507966
0.50 - 30.07360
CISPR 22/ EN 55022 Class B Conducted EMI Limit
Frequency of Emission (MHz)Conducted Limit (dBuV)
Quasi-peakAverage
0.15 - 0.5066 - 5656 - 46
0.50 - 5.005646
5.00 - 30.006050

Conducted EMI Results

We use the EMCView software to conduct our EMC pre-compliance testing, which was kindly provided by TekBox Digital Solutions.

As you can see, our equipment measures low EMI conducted emmissions that fall in line with the corresponding requirements.


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  • JohnnyLucky
    Nice review. I'll add it to the psu recommendation list I maintain.

    Last week newegg had the 650 watt model on sale for $74.99. There was a $20.00 mail-in rebate which brought the price down to $54.99. On top of that there was a free $30.00 gift certificate for a fresh food vendor online which my wife wasted no time in using. That brought the final price down to $24.99. Best deal I've taken advantage of this year.
    Reply
  • JohnUSA
    I just found this model selling for just $74 at SuperBiiz-dot-com, which I think is a great deal.
    Reply
  • buzznut47
    This was rated highly by JonnyGuru, and based on that I made a purchase 2 or 3 months ago. I have been mostly happy with its performance. I am running an FX 8320 @3.8 Ghz, 2 R9 280X, custom loop with 8 fans, and a couple of drives.

    Initially I was really impressed that there was so much power in such a small package. Until I saw the cables, and the ridiculous capacitors. I know this brings a fantastic level of ripple, but I don't like it at all.
    I gotta say, I really don't like this trend with higher end power supplies. As a modder, my cables are visible. And these cables would be satisfactory, if the capacitors were located ON THE PSU SIDE!! But they are located on the component side where they can be seen in all their glorious ugliness. It is not recommended to change the polarity..
    I will be checking the units I buy more carefully moving forward. I would much rather have a longer power supply unit that has the caps inside.

    Bottom line though, it is a gold 850W unit at an affordable price and a 10 year warranty. For efficient cards like the RX570/580 and GTX 1060, there are enough cables for 6 video cards. Pretty good for mining, but as for a visible gaming rig I have to say 4 out of 5 stars for functionality. Just put the caps at the other end of the cable, ya big dummy.
    Reply
  • berezini
    Still haven't changed my mind on getting one after killing my new motherboard and couple other components. Just would never recommend seasonic ever again.
    Reply
  • ZRace
    Great review, looks like this will be my next PSU unless something better releases by the time I need a replacement. Definitely gonna recommend this to others!
    Reply
  • JohnnyLucky
    ARIS - Are you still here?

    The PCIe cables are a little different than what I am used to. The 850 model and my 650 watt version have PCIe cables with two connectors instead of just one at their device end. Does that mean one PCIe cable can be used for both connections on a graphics card? On the other hand do I still have to use two PCIe cables and let one connector on each cable just hang there?

    Anybody else know?
    Reply
  • Leaps-from-Shadows
    20427267 said:
    Still haven't changed my mind on getting one after killing my new motherboard and couple other components. Just would never recommend seasonic ever again.
    Even the best manufacturers produce the occasional lemon. It's too bad you're one-and-done -- you're really missing out on quite possibly the best power supplies out there.

    It's okay though ... they will survive without your money.
    Reply
  • Leaps-from-Shadows
    20430290 said:
    ARIS - Are you still here?

    The PCIe cables are a little different than what I am used to. The 850 model and my 650 watt version have PCIe cables with two connectors instead of just one at their device end. Does that mean one PCIe cable can be used for both connections on a graphics card? On the other hand do I still have to use two PCIe cables and let one connector on each cable just hang there?

    Anybody else know?
    You can certainly use the two connectors from a single cable. However, a video from JayzTwoCents showed it was better to use two separate cables.
    Reply
  • JohnnyLucky
    Leaps - Thanks for the info.

    I went back and read the review. In the specs it shows 3 PCI-e cables and 6 connectors. It also indicates the 3 cables could be used with 3 video cards, each requiring 2 connectors.

    I'll take a look at the video. I've watched some of his other clips.

    Don't know how I missed this development.

    Reply
  • Leaps-from-Shadows
    20430533 said:
    Leaps - Thanks for the info.

    I went back and read the review. In the specs it shows 3 PCI-e cables and 6 connectors. It also indicates the 3 cables could be used with 3 video cards, each requiring 2 connectors.

    I'll take a look at the video. I've watched some of his other clips.

    Don't know how I missed this development.
    Here it is, in case you couldn't find it...
    Reply