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SeaSonic SS-300ET Bronze 300W ATX12V V2.3 80 PLUS BRONZE Certified Active PFC Power Supply

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  • ATX12V V2.3
  • 80 PLUS BRONZE Certified
  • 100 - 240 V 47 - 63 Hz

  • Overview
  • Specs
  • Warranty & Returns
  • Reviews

The SeaSonic SS-300ET Bronze power supply is designed with the value-conscious user in mind. Certified 80 PLUS Bronze, this active PFC unit runs at up to 85% (or higher) efficiency while delivering a 50% load, so you know you're saving energy and money on your power bills month after month. With 300W of total output power, there's plenty of juice for the most home or office situations.

Featuring short circuit protection, the SeaSonic SS-300ET Bronze power supply provides the maximum reliability. Cooling is handled by a 120mm fan with super low noise control. A hexagonal grid pattern on the back panel ensures that the components will get plenty of airflow to keep the power supply cool and operating at peak performance.

  • newegg ATX 12V Compatible Compatible with the ATX12V v2.3 standard, the SeaSonic SS-300ET Bronze power supply provides maximum power stability to drive the processors as well as other system components.
  • newegg 300W Maximum Power A maximum power of 300W delivers safe, reliable output for average computer systems.
  • newegg 80 PLUS Bronze Certified The 80 PLUS Bronze certified power supply provides high power efficiency of at least 82% at any load between 20% and 100%, saving your money on your electrical bill, reducing heat in your computer's system and prolonging its life.
  • newegg 120mm Cooling Fan The SeaSonic SS-300ET Bronze power supply features a 120mm fan for increased overall airflow and heat dissipation in the power supply enclosure.

Learn more about the SeaSonic USA SS-300ET Bronze

Warranty, Returns, And Additional Information
  • Warranty
  • Limited Warranty period (parts): 3 years
  • Limited Warranty period (labor): 3 years
  • Read full details
  • Return Policies
    • Return for refund within: 30 days
    • Return for replacement within: 30 days
  • This item is covered by's Standard Return Policy.
Ownership: 1 month to 1 year
Verified Owner
1/ 5
Poorly designed, short cables 12/14/2017 10:30:48 AM

Pros: It powers a computer if the case is small enough.

Cons: The 8-pin molex cable for the motherboard cannot reach across an ATX motherboard. If you have a case where the PSU is on the bottom and your motherboard's 8-pin connector is at the top, it will not connect. It is absurdly short.

Overall Review: Stay away unless your case has the power supply at the top or you are using a small motherboard.

Did you find this review helpful?
Manufacturer Response:
Hello Phillip,

Thank you for your comment and sorry that this product didn't satisfy you. Note that this is a bulk unit made for industrial application where cables length may not match the need of a retail case. We are sorry for it and we do hope that you can consider instead our S12II Series.

Sorry for the inconvenience it may have caused you.
Best Regards,
Ownership: more than 1 year
Verified Owner
5/ 5
Efficient, Quiet, Reliable 9/7/2017 1:40:22 PM

Pros: I've bought about at least 100 of these over the last five years. Most run 24/7 in desktops and servers. Other than one unit that had a problem right out of the box, I haven't had a single failure or problem of any kind. I've used many brands and models of power supplies over the years, and these are by far the best. They run whisper quiet, 300W is more than enough for any system or server I have, and the power savings are significant. Best of all is the reliability. It's something you can only know after running a many units for years and not having any problems.

Cons: None.

3 out of 3 people found this review helpful. Did you?
Ownership: more than 1 year
Verified Owner
5/ 5
Amazing PSU 12/7/2016 10:27:41 AM

Pros: I have now had this PSU(s) I bought 4 of them for over a year now. There are being used to power 4 server boxes. These servers are turned on 24/7/365. They are super quiet and efficient. I sometimes have to check if the server box is actually on as I cannot hear the PSU FAN turning away. Did I mention it is efficient ?

Cons: None

Overall Review: I would highly recommend this product.
Mind you do your homework and do not expect to use this type of PSU to power 2 video cards and HDD and everything else. This is for mid-range builds and for mid-range server builds.

Did you find this review helpful?
Ownership: more than 1 year
Verified Owner
5/ 5
Still running after 5 years 5/31/2016 6:43:50 PM

Pros: -Very quiet
-Very reliable

Cons: -Not Haswell compatible (at the time I bought it)
-Power output isn't suitable for energy hogging video cards

Overall Review: What can I say, if something performs well, it's almost invisible. That's been the case with this PSU when I bought it in 2011. Granted, I've never drawn more than 110 watts with it according to Kill-A-Watt, but it has never failed during that time. I don't know how well it would hold up in a 24/7 situation, but for what you get, it's very nice.

Did you find this review helpful?
Ownership: 1 month to 1 year
Verified Owner
1/ 5
Dead and can't RMA 12/1/2015 1:28:15 PM

Pros: Really inexpensive. Pretty quiet.

Cons: Died after 10 weeks and the RMA process at is busted. After completing their detailed form the RMA cannot be submitted because they don't recognize serial numbers for SS-300ET. I thought Seasonic was better than this.

1 out of 2 people found this review helpful. Did you?
Manufacturer Response:
Hi Andrew,
Thank you and sorry for the inconvenience of the failed power supply. If you have any questions or to process your RMA, kindly please contact: Thank you.
Ownership: 1 month to 1 year
Verified Owner
4/ 5
No power cable included 10/25/2015 3:19:18 PM

Pros: Good price and silent.

Cons: I had to go buy a power cable because it wasnt included.

3 out of 5 people found this review helpful. Did you?
Manufacturer Response:
Hi Kyo, Yes, this power supply does not come with a Power Cable because this model is for system builders and not for consumer purchase. If you wish to purchase a Seasonic PSU that comes with a power cord, then please consider one of our Retail models. Thank you.
Ownership: 1 day to 1 week
Verified Owner
5/ 5
Nice and very quiet 8/21/2015 6:34:06 PM

Pros: WIth the 120mm fan it's pretty silent. It wasn't expensive and sure beats a cheap one that makes grinding noises out of the box.

Cons: It doesn't come with a power cable. I've got about 100 power cables so I don't care. OEM boxed or just kinda loose with no box. In other words NO PACKAGING.

Overall Review: It's great if you realize it's just OEM packed. If you're a noob and don't know what OEM parts are you might be sad.

2 out of 2 people found this review helpful. Did you?
Ownership: less than 1 day
Verified Owner
2/ 5
Cables too short 6/15/2015 1:02:31 PM

Pros: I'm sure the pros from other reviews apply here. I'm unable to actually use the PSU for the reasons below.

Cons: My PC case has a bottom mount for the power supply. The main power cable is not long enough to reach the socket on my motherboard. It's short by a good 2-3 inches. I will have to purchase an extension.

3 out of 4 people found this review helpful. Did you?
Manufacturer Response:
Hi Matthew, Thank you for your review. Please note, the 300ET is for smaller sized cases and for system builders where the cable lengths are fairly fixed and short... therefore the cable lengths are not as long as some of our other models. Please check out our RTL power supplies and for these, the cable lengths are much longer. If you have any questions or comments, please write to: Thank you
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