Seasonic Prime Ultra Platinum 1000W PSU Review

Tom's Hardware Verdict

The SSR-100PD Ultra is the best performing PSU with 1kW capacity that money can buy today. We haven't tested of course its Titanium (or ETA-A+) sibling yet, which will most likely achieve an even higher overall performance rating, so for the moment this model is the king of our charts.


  • +

    Full power at 47°C

  • +


  • +

    Ripple suppression

  • +

    Load regulation

  • +

    Hold-up time

  • +

    Accurate Power Ok signal

  • +

    Transient response

  • +

    Silent (for a 1kW PSU)

  • +

    Build quality

  • +


  • +

    Fully modular

  • +

    2x EPS & 8x PCIe connectors

  • +

    2x SATA connectors supporting SATA 3.3 spec HDDs

  • +

    FDB Fan

  • +

    Selectable semi-passive mode

  • +


  • +



  • -

    Distance between peripheral connectors

  • -

    OCP at 5VSB

Why you can trust Tom's Hardware Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.

Features & Specifications

Not long after introducing its Titanium, Platinum, and Gold Prime families, Seasonic is ready with a wave of replacements that add the word "Ultra" to each model name. The new PSUs come with improvements that include:

  • Smaller dimensions for the lower-capacity Prime units (550W to 750W). Only the 1kW Prime Ultra remains 17cm-deep.
  • No in-cable caps, making the power cables easier to work with.
  • Two of the SATA connectors are now SATA 3.3-compatible, meaning they support the so-called Power Disable function.
  • More relaxed fan profiles.
  • A tester is included for jump-starting the PSU without the need of a motherboard.

All of Seasonic's changes are welcome, in our opinion. The one we're most excited about, though, is the use of more relaxed fan profiles, which should help these PSUs operate at lower noise levels. And according to Cybenetics' acoustic results, the new models indeed fare better in this discipline (particularly the higher-capacity ones). On the surface, it seems like Seasonic is utilizing lower fan speeds and modified control circuits to keep the profiles as conservative as possible.

In-cable caps might improve ripple suppression, but they also render cables bulky and more difficult to work with. They also make it nearly impossible to create ribboned cables. So, we prefer all filtering caps to be inside the PSU's chassis where they can be cooled down properly. Seasonic did use in-cable caps on some of its previous Prime models. However, the Prime Ultras don't have them any more.

The Prime Ultras incorporate changes to some of their SATA connectors, too. For starters, there is support for SATA 3.3, meaning that this PSU's bundle comes with a special SATA cable, which doesn't expose the 3.3V rail on the connector's third pin. Instead, it enables the Power Disable function, allowing you to manage SATA power consumption and remotely hard-reset drives. If you combine a SATA 3.3-capable drive with an older PSU that doesn't have a corresponding SATA connector, then the 3.3V rail will still be present on the SATA connector's third pin, forcing the drive into a continuous hard reset condition. As a side note, this feature has to do mostly with high-capacity storage, so if you plan to purchase mechanical disks in the near future, make sure they support the Power Disable feature and that your PSU has the proper SATA connectors to match.


The SSR-1000PD Ultra can deliver its full power continuously at 40°C, while at 50°C it's rated for 80% of that capacity ceiling. Apparently, the mining business is forcing PSU manufacturers to be more realistic about the temperature ratings of their products, and that's good as far as we're concerned. We wouldn't be surprised if many of the vendors claiming they can deliver full power at 50°C continuously actually can't.

This PSU's suite of protection features is complete, while its 135mm cooling fan is based on a fluid dynamic bearing. A selectable semi-passive mode deactivates the fan under light and moderate loads, and a 17cm depth measurement qualifies as compact enough for a 1kW PSU.

Seasonic's 12-year warranty is still as good as it gets, though we find such generous coverage to be optimistic. After all, a PSU's longevity is highly dependent on external factors like the grid's quality and stability. In truth, though, Seasonic's support is amazing, so we're less concerned about the company's ability to remedy issues than some of its competition.

Power Specifications

Swipe to scroll horizontally
Max. PowerAmps25258330.3
Total Max. Power (W)1000

The single +12V rail can almost deliver the SSR-1000PD Ultra's full power on its own, while the minor rails are strong enough with 125W of maximum combined power. Finally, the 5VSB rail has sufficient capacity.

Cables & Connectors

Swipe to scroll horizontally
Modular Cables
DescriptionCable CountConnector Count (Total)GaugeIn Cable Capacitors
ATX connector 20+4 pin (610mm)1118-22AWGNo
4+4 pin EPS12V (650mm)2218AWGNo
6+2 pin PCIe (680mm+80mm)4818AWGNo
SATA (400mm+110mm+110mm+110mm)2818AWGNo
SATA (350mm+150mm+150mm+150mm)1418AWGNo
Four-pin Molex (450mm+120mm+120mm)1318AWGNo
Four-pin Molex (350mm+120mm)1218AWGNo
Four-pin Molex Adapter / SATA (150mm+150mm)1218AWGNo
FDD Adapter (+100)1122AWGNo
AC Power Cord (1360mm) - C13 coupler1118AWG-

You get a great many cables and connectors with the SSR-1000PD Ultra, as expected from a high-end 1kW PSU. Eight PCIe connectors are plenty, even for top-end gaming PCs, while there are lots of SATA and four-pin Molex connectors to cover every possible usage scenario. Only cryptocurrency miners could want more PCIe connectivity. But if you want a highly capable mining machine, it'd be better to start shopping in the 1.2kW range (at least), reducing stress on your PSU and allowing it to run more efficiently.

Besides the 180o SATA connectors, Seasonic also offers two cable options with different distances between SATA connectors, covering as many usage scenarios as possible. The distance between four-pin Molex connectors should be greater than 15cm, though. Thankfully, the total length of all cables is sufficient. You won't have any trouble making connections in full-tower enclosures.

Bear in mind that the cable with one four-pin Molex adapter and two SATA connectors supports SATA 3.3-based HDDs. In this cable, the 3.3V rail is absent from the SATA connectors, since it doesn't exist on the four-pin Molex connector responsible for feeding them power.

Power Distribution

Because this PSU features a single +12V rail, we do not have anything to say about its power distribution.

MORE: Best Power Supplies

MORE: How We Test Power Supplies

MORE: All Power Supply Content

Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.

  • Th_Redman
    I notice you didn't give it an award rating...what gives, if you present it with such high praise?
  • Aris_Mp
    It has an award. It is just not shown, yet :)
  • Kennyy Evony
    Lets all hope it doesn't kill your motherboard and all components like my SeaSonic did while only operating 1 year under light workloads. No matter how much change they make to PSU I would not trust a brand that would allow catastrophic results in using their products AND not accept responsibility for the loss.