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Cooler Master MasterWatt 550W Power Supply Review

Author: Lee Garbutt
Manufacturer: Cooler Master

Final Thoughts and Conclusions

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Cooler Master’s new MasterWatt power supplies are an update of their mainstream power supply lineup. All four MasterWatt power supplies feature semi-fanless operation, modular cables, 80 Plus Bronze level efficiency, and come backed with a 5-year warranty. Note: the two MasterWatt Maker 1200W PSUs are 80 Plus Titanium certified and come with a 7-year warranty while the two MasterWatt Lite PSUs are 80 Plus white, have fixed cables and come with a 3-year warranty.

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The MasterWatt 550W power supply comes with a standard assortment of semi-modular cables with a combination of sleeved fixed and flat ribbon-style modular cables. The 120mm Cooler Master Silencio fan uses a Loop Dynamic Bearing (LDB) for long life and quiet operation. The power supply also features semi-fanless operation when power output is below 15%. During our tests the MasterWatt power supply delivered good voltage regulation along with good AC ripple suppression. The MasterWatt series comes backed by a 5-year warranty.

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The MasterWatt PSUs are currently entering retail channels.

•    MasterWatt 550W: $59.90 USD ( October 2017)

•    550W Continuous DC output at up to 40°C
•    Semi-fanless operation below 15% load
•    80 PLUS Bronze certified
•    Good voltage regulation
•    Good AC ripple and noise suppression
•    Quiet 120mm Loop Dynamic Bearing (LDB) cooling fan
•    Modular cables
•    Safety protections: OPP, OVP, UVP, OCP, OTP and SCP
•    5-Year warranty

•    Teapo caps with 85°C rating

Overall a good basic power supply with minimal frills.

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Cooler Master MasterWatt 550W Power Supply

Our thanks to Cooler Master for sending us the MasterWatt PSU to review.


December 3, 2017 | 10:17 PM - Posted by Pink Gnome (not verified)

Surprisingly good for the price. Is there really any practical difference in functionality of any system components between this powersupply and, say, seasonic platinum 550 watt?

December 4, 2017 | 12:22 PM - Posted by Lee Garbutt

Good question. The practical functionality is similar (they both convert AC mains power to the DC voltages required for a PC to operate) but how they do it, how well they do it, and potentially for how long they  keep doing may be quite different. The MasterWatt PSU is a mainstream PSU targeted towards the mass market/average user while the Seasonic Platinum PSU is targeted towards PC enthusiasts looking for a premium PSU.

Compared to the MasterWatt, a Seasonic Platinum PSU uses a more sophisticated design, more components, higher quality components, and includes a longer warranty. These differences result in higher efficiency, better voltage regulation, and reduced AC ripple and noise on the DC outputs, which can potentially make your system more stable and live longer.

December 4, 2017 | 09:11 PM - Posted by Pink Gnome (not verified)

Thanks for the detailed answer!

December 4, 2017 | 01:13 AM - Posted by Cyric (not verified)

I would like to know the OEM for this supply. Coolermaster has a history of using seasonic as an oem which is a good thing.

December 4, 2017 | 12:25 PM - Posted by Lee Garbutt

No, the MasterWatt 550W is not made by Seasonic. Cooler Master appears to be using HEC (based in Taiwan) as the OEM for the MasterWatt series.

December 21, 2017 | 01:43 AM - Posted by Tech We Love (not verified)

Could you test room temperatures at the different watt % usages ? I would like to know how much the room temp rises at each level of power usage.

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