Seasonic Vertex GX-1200 PSU Review

The Seasonic Vertex GX-1200 offers high build quality, good performance, silent operation, and ATX v3.0 and PCIe 5.0 compatibility. How it fares though, against competiting offerings? Read the full review to find out. 

The Seasonic Vertex GX-1200 is included in my best ATX v3.0 & PCIe 5.0 PSU picks article.

The Seasonic Vertex GX line includes four members with capacities ranging from 750W to 1200W. All models of the line are ATX v3.0 and PCIe 5.0 ready and are supported by an extended, ten-year warranty. Seasonic has a solid reputation in the PSU market, and the Vertex line addresses the mid-segment, with the Prime models on top of them and the Focus models below. The Vertex GX-1200, which I will evaluate in this review, is a strong unit capable of handling an RTX 4090 paired with a power-hungry CPU, like the Intel i9-13900K(s). Given that the RTX 4090 can exceed 600W in power spikes and 600W in sustained power, and the 13900K is close to 370W sustained at stock speeds, it is better to have a 1200W PSU for such a combination to have enough room.



With 160mm depth, this is a compact PSU, given its capacity, so you won’t have any compatibility issues with standard ATX chassis. Thankfully the PSU’s casing is large enough to accommodate a 135mm fan, which utilizes a fluid dynamic bearing for increased reliability and lower noise output.


Technical Specifications:
  • Manufacturer (OEM): Seasonic
  • Max Power: 1200W
  • Cybenetics Efficiency: [115V] Cybenetics Gold (87-89%)
  • 80 Plus Efficiency: Gold
  • Noise: Cybenetics A- (25-30 dB[A])
  • Compliance: ATX v3.0, EPS 2.92
  • Operating Temperature (Continuous Full Load): 0 – 50 °C (derating from 100 % to 80 % from 40 °C to 50 °C)
  • Alternative Low Power Mode support: Yes
  • Power 12V combined: 1200W
  • Number of 12V rails: 1
  • Power 5V + 3.3v: 125W
  • Power 5VSB: 15W
  • Cooling: 135mm Fluid Dynamic Bearing Fan (HA13525H12F-Z)
  • Semi-Passive Operation: ✓ (selectable)
  • Modular Design: Yes (Fully)
  • High Power Connectors: 2x EPS (2x cables), 3x PCIe 6+2 pin (3x cables), 1x PCIe 12+4 pin (600W)
  • Peripheral Connectors: 18x SATA (5x cables), 3x 4-pin Molex (single cable)
  • ATX Cable Length: 620mm
  • EPS Cable Length: 710mm
  • 12VHPWR Cable Length: 750mm
  • Distance between SATA: 150/160mm
  • Distance between 4-pin Molex: 125mm
  • In-cable capacitors: No
  • Dimensions (W x H x D): 150 mm x 85 mm x 160mm
  • Weight: 1.96 kg (4.32 lb)
  • Warranty: ten years
  • Street price (excluding VAT): $296

Power Specifications

Rail 3.3V 5V 12V 5VSB -12V
Max. Power Amps 25 25 100 3 0.3
Watts 125 1200 15 3.6
Total Max. Power (W) 1200
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53 thoughts on “Seasonic Vertex GX-1200 PSU Review

  1. Massive coil whine on 3 Gx 1200 units when pc is at idle or when pc is off.


    There are posts about this issue on reddit, youtube and tomshardware.
    I never had such issue with psu it was so annoying, i returned my old non atx3.0 psu and its quiet again.

    I guess there are some new atx 3.0 parts inside causing thiss issue maybe.

    1. I have used several of them in my test systems with zero coil whine. I’ve even taken noise measurements close to 15 dBA with one of them in operation, without the fan spinning. Coil whine is due to lots of factors, not only the PSU.

  2. Nice review as usually by Hardware Busters! My previous psu was also Seasonic, I bought this for the new atx 3.0 standard specs. Great psu from Seasonic leader. Powerful and silent. It’s really the heart of your system. Mine, no coil whine. I was lucky and I bought it for 240€. At this price there is nothing better in atx 3.0 series. Seasonic quality, no worries for at least 10 years. Once Seasonic, for ever Seasonic.

    Ευχαριστώ Άρη για άλλη μια φορά.

    1. Thank you very much for looking into this issue, i never had such annoying high pitch sound on any psu ever like this Gx. For this build i went with seasonic vertex gx 1200 cause of quality i paid 340 euros but was dissappointed and returned it after 10 days i hoped for the noise to go away but nothing.
      And the crazy thing is that when pc is off and switch off but power cable still in it still whines thru whole night to the point that i though that all of a sudden i got tinitus in ears.

      Now im 3 weeks without psu im interested in be quiet 12m at 200e for my 4090/7700x hope thats ok psu.
      Again thank you for your time and work.

  3. Coil whine on mine also, buzzing like sound so i put it under my desk but when i turn off my pc its still buzzing and i can hear it its like electric buzz for 5 or 6 seconds and then again after cca 10 seconds and thru whole night its insane.
    I tried erp mode in bios but still the same.

    32gb ram

    1. Hm, this starts to get weird. I will discuss with Seasonic and I will probably remove it from my best PSU’s page. Problem is that currently I am at Computex, with not much time to work on the site.

  4. Greetings,

    I would like to ask a question if I may. For the short circuit protection (SCP) feature of PSUs, does it only work when our house is grounded and it is useless when the house is not grounded?

    Many thanks

  5. My GX 1000 also suffered obvious coil whine. There is a thread on Tomshardware where multiple GX users from a couple months back had noticeable coil whine and electrical crackling/buzzing sounds, sent their units back.

    I had to do the same. The frequency was grating, worst when the machine was idling or near idling, which is much of the time. Didn’t matter if it was in Eco with the fan off or turned on. Pretty easy to hear even above six case fans and an AIO pump when I was two metres away. I felt this was a premium product and would be better.

    I had an 8 year old EVGA Supernova P2 850W lying about I knew was good, swapped that instead and it’s dead silent. Have to put my ear within 20 centimetres to the exhaust of this EVGA unit in eco mode with the fan off to hear anything at all. Kinda sad for the Seasonic. It cost more than twice as much as the platinum EVGA. Yes it’s 8 years later and yes it’s ATX 3.0 but I was disappointed to see these reports of GX coil whine and experience it for myself.

      1. Does Seasonic still send review units directly from places like Newgg or Amazon? If so getting a “golden sample” seems quite rare.

          1. Funny, that sound I had for few minutes on a GX-850 Focus too, after the psu went into protection mode. But dissapeared late.
            Is there a special scenario when the PSUs go into this nosy mode, I wonder?
            Because of some stability issues with my new system opted for a new psu… I am still not sure if the 6y old fsp hydro g 850w had to be replaced… but now I am really wondering if I willl still keep one of the new PSUs (Focus GX850 and Prime GX1000) or just send them back.

          2. What do you mean by “went into protection mode”? Did the PSU shut down?
            Also noisy mode? You mean the fan spins at high speeds making noise? Or coil whine?
            Sorry I didn’t quite understand what you wrote.

  6. I have a Vertex GX-850 and haven’t had any coil whine. Stability in my old 4770K with RX6700XT is great. Even when pushing the GPU and CPU to full load the semi-passive mode keeps the PSU silent.

  7. Can confirm, cricket like noise on my gx 1000w
    And coil whine at idle or when browsing the web in games its very quiet.

    Rtx 4080
    32gb ram

    1. I just talked to Seasonic and they told me that they will look into this ASAP! Because several users already reported this in these comments.

  8. Even with other users experiencing some kind of coil whine. I decided too go with this psu in the end. I like that seasonic has upgraded the cables to sleeved now. Those other cables were very bulky. I had to upgrade because I am getting pc shutoffs from my current 850w prime titanium. Seems to be a thing with pre-2018 psu’s from seasonic. The price is pretty high. Considering I got a 850w titanium for $219.99 in 2018. The price for gold is a bit eye a little bit more power.

  9. I also have buzzing on my gx 1000w, only occurs when idle.
    Unfortunately I built the pc after the return window passed.

    Asus x670e-I

  10. Unfortunately, I will add another case of coil whine in here.
    My GX-1000 unit also has a constant cricket like sound when the PC is idling or pulling little power from the unit.
    I’ll probably end up switching to my old PSU which happens to be also a seasonic, very old but whine free and try to RMA this new one. 🙁

  11. Sadly, I have buzz/ cricket sound on my PSU too.
    I´m running GX-1000W with Ryzen 7900, B650E Asrock MB, GTX960 (patiently waiting for RX7800/XT launch…).
    Appearing under <200W or idle. For around 230€ it´s really bad.
    Reason for this buy was future proofing and SEASONIC brand (ATX3.0, Ryzen 8xxx, RTX5xxx).
    I wouldn´t reccomend this PSU to anyone of my friends. Bought in Czech republic.

    1. There seems to be an issue in the Vertex according to many user reports I got so far, and this is why I removed them from our best PSU picks article. That said, both my GX-1200 work ok without coil whine issues, in several system configurations I tried. weird..

  12. I put 12 vertex PSUs into gaming builds I put together for sale for customers and can say zero noise of any kind , no coil whine , can’t even hear the fans , three of these were water cooled units that have light gpu coil whine I can hear but confirmed it was the strix gpus and not the PSUs

  13. Do we have any update on the coil whine from Seasonic? It seems that all alternatives are either much larger (>=180mm) or much noisier (>35dBA). I’m also hoping to keep all units at home under the same brand for easier swapping and my current Seasonic ones are rock solid.

    I also found Amazon reviews on coil whine regarding one other small option, TT GF3: Not sure about NZXT C1200 and Montech Titan with the same platform.

    1. Some users do have coil whine, while others don’t. The fact is that most ATX v3.0 PSUs have problems with coil whine, caused by the resonant tank as I hear.

  14. Is it only for 1000W and up? Never seen report for 750w version for the coil whine. Any thoughts?

  15. Hey guys,

    Same issue here. My system was running smooth and silent for about 2-3 weeks, but then the PSU coil whine appeared.

    Any potential solutions? (besides buying and testing a new ATX 3.0 PSU)

    Seasonic Vertex GX – 1000 gold
    Ryzen 7800x3d
    Gigabyte Aorus X670-AORUS-ELITE-AX

  16. Hi,
    great review but there is something very odd here with the teardown photos. Why there are TWO 12vhpwr connectors on the PSU when there is only one outside? is the other one covered up by the shell. That’s odd.

    I have this PSU, it only has one connector and you can see in the product pictures that it only has one.

  17. My GX-1200 unit has coil whine, but it’s extremely quiet – In order to hear it you need to have your head pretty close to the PSU itself. It’s the typical cricket type sound, but it’s so subdued that I don’t see the point of returning the unit, since coil whine doesn’t indicate failure. Correct me if I’m wrong. Plus I can always hope it’ll lessen with time. If I didn’t see other people mention it I never, ever would have noticed it.

    Performance has been great, but the unit does heat up the rear grill and metal shroud on my case unlike any other PSU I’ve used. Maybe it’s due to the location of the components, but it seems to run hot.

    That being said, it’s hard to hear it over my Noctua exhaust fan, which in my mind means it’s just not a big enough problem to stress over. Unlike the NZXT C1200 which I did indeed have to return because the chirping was loud enough to hear from a room over. It was like a dying bird.

    Definitely an expensive unit, but I bought it because I liked the cables. Hopefully it stands the test of time.

  18. Any chance you can check the 12VHWPR cable and confirm what terminals Seasonic uses? NTK or Astron?
    I have a new 1000W right next to me but it’s sealed and I don’t want to open it because that’ll void my return for a refund.
    Thanks for the great review!

      1. Too bad. I was hoping it’ll be NTK because they look safer and more reliable. Your thoughts?
        Thanks for the confirmation though.

  19. I’ve had my Vertex for about two months and can not believe how quiet it is. I paid around $250 for the 1000, which was high, but it seems to be performing well. I’ve seen some videos of some units, and mine is nothing like that. You can barely hear my PSU and there’s zero coil whine. I’m extremely happy with this and I’ve seen its been dropping in price recently. I think it will eventually be a great deal here soon. I wonder if there was a bad batch on first release.

  20. does the PX is on the way for a review?

    i got my Gx 1000 one month ago, and it is dead silent. i can not hear any coil whine whatever the load, even my ear on it

  21. I bought the Seasonic Vertex GX-1200W for 185 Euro ($200). Black Friday Week deal. I love it. It’s silent, no coil whine. Use it with rtx4090, I9-14900K, Rog Maximus Z790 Dark Hero.

  22. If you want to avoid risk to get a Seasonic with coil noising, buy instead a German engineered PSU, the BeQuiet! Pure Power12M -1200W. They are famous for their high quality psu’s.

  23. Seasonic gx-850 ATX3.0 or rmx shift 850 which would you get? i asked because the vertex had the same fan as the gx model

      1. All my Vertex samples work just fine. I even use them for noise measurements in the chamber, where the ambient with the PSU in operation and with a silent Noctua cooler (at low RPM) is below 10 dBA. Coil whine is something that is related to the rest hardware as well, not only the PSU.

  24. Would there be a noticeable increase in quality and is it better to pay the difference and buy the 1200 PX?

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