[Flat, Modular] Great power supply from Seasonic. It is a bit shorter than the previous power supply I had and mostly silent. Stable power and very long warranty.

[ATX] Still waiting for my CPU to be delivered. Cables have which end goes where on each end and the PSU has easy to read plug labels. I find it easy to get overwhelmed by all the cabling, so having each cable labeled is really nice when moving from back to the front of the PC case. This will be my third PC with a SeaSonic PSU, and I fully expect it to last as long as the other two (which are still going strong years later). This version has the 12/16 pin 600w connector, but I went with a 7900XTX, so it's not needed.
As I have yet to fire it up, I cannot say how quiet or loud the fan is, but the other two were/are effectively silent. And as it is brand new, I cannot say how long/well it will perform. My positive experience with my prior two purchases leads me to believe this one will perform as well as they do.
Reputation is such a fragile thing. Noctua has a great one and Arctic is building a great one.

[ATX] Got what I expected and so far no issues. Seasonic looks and feels like higher quality products when compared with some of the more inexpensive power supplies out there. Worth it for a little extra piece of mind.

[1200 W] Reliable power and all the features you'd expect. Modular design makes cable routing and management easy. It's overkill for my current setup (7850X3D and 3080TI, but provides room to grow. No complaints and would buy again.

[50,000 Hours] What to say....
It is Seasonic, its Platinum and it is ATX3. It lives up to all of the expectations.
Its only down side is that it has an Eco button but that is probably there to satisfy the EU regulators so I can live with it in the off position.

[92% at 50% Load] I built my pc with 9900k and Gtx 1080. I had fast ram and a great motherboard, but I always had stutters. I optimized and redid my settings so many times and windows reinstalls later, I realized I had a hardware problem. I upgraded my gpu to an RTX 3090 and still had stutter. So I decided to buy a 4090, 13900k, new mobo, nvmes and 3 different sets of ram. Still stutters with one of the best systems you could buy. Rma for my 1000w EVGA 80 Gold and still experiencing stutter with a “new” psu, I decided it was time to switch to the Seasonic pcie 5.0 psu and have instantly had a smooth experience and all stutters have been smoothed out!

[1200 W] Some power supplies are quiet most of the time, but the SeaSonic PX-850 is quiet all the time.


It lets you opt into having the fan shut off under low load via a physical switch. This is great if you find the fan turning on distracting, instead it will just run slowly when load is low and increasing the speed when under more load.

[15 W] Worked great! No issues getting it setup in my case in terms of cable length (Fractal Design North). Having the new 12v high power connector was perfect for me, no squid looking adapter hanging off my GPU and no concerns about faulty adapter causing my brand new GPU to catch fire. Additionally with the high output and efficiency I've got no concerns about this PSU staying in my system for years to come.

On the negative side a few minor quibbles. The price is high for a PSU, (but then again what isn't nowadays). And second the connectors were really tight when trying to insert them on my Asus motherboard.

[100 A] The 1200W limit is excessive for most applications but if efficiency is a concern the higher wattage helps keep your PC in the optimal part of the efficiency curve. Excellent PSU.

[3.6 W] Pros:

- Very powerful, 1200W, Platinum 80+ Class;
- ATX 3.0 & PCIe 5.0 Compliant;
- Fully modular;
- Hybrid fan control;
- Compact size, 160 mm length;
- Very high quality all components;
- All types of cables, screws and straps in pack.

Cons: None

Overall Review: My previous power supply was Gold class, so I never had such wonderful PS before.
This one is a new level - Seasonic Platinum Class - Piece of Art.
Everything in package: Power Supply and cables are very high quality items, even screws.
I've used supplied tester and user's manual for checking PS after unpacking, in normal mode with fan on. Installation Guide is clear and understandable.
Assembling the new PC with this Power Supply was a pure joy and pleasure. Simple and easy.
Power Supply works very quiet even under pretty heavy load.
Totally I'm very satisfied with purchase of this Vertex PX-1200. Looking forward to apply 12VHPWR cable with a new video card.

Power Supply is a heart of PC, it should be very high quality thus it can't be cheap. This one is the highest level of PS which I ever saw and hold in my hands.