Cooler Master G550M: 80+ Bronze, DC-DC and modular cabling from Channel Well

Conclusion and evaluation

The Cooler Master G550M passed the combined and crossload testing in accordance with the ATX specification, so according to my evaluation methodology, it deserves its evaluation. The interesting thing is that this unit’s evaluation quite depends on the market it is being sold onto. At the moment in Czech republic, the V Semi Modular family from Cooler Master is occasionally cheaper than the GM series. Even though it has been evaluated as high-end unit, in absolute comparison, even the older revision is better than the GM in terms of efficiency, voltage regulation and ripple suppression, maybe just the noise is a tiny bit higher (especially with higher load). On the other hand the GM overheats with higher load which will definitely not help those poor quality capacitors.

But in terms of mainstream itself, the G550M is not really that bad. If the V Semi Modular is priced much higher in your country, the GM is probably one of the cheapest units on the market with modular cabling and DC-DC modules, which – even if they are not so good as could be – usually rule over group design any day of the week (remember the Antec Earthwatts Platinum 550 W we reviewed recently). And despite using quite terrible capacitors and baking them in their own electrolyte with very high temperatures, it is at least covered by five-year warranty. So it may be really interesting if you are low on budget and it depends on what the competition is on your market.

Because units with DC-DC modules are popping in market like mushrooms after rain these days, the same with modular cabling and high efficiency, having similar unit but with higher-quality components or higher efficiency with just a slightly higher price may be the deal breaker for the GM series. Like with the V Semi Modular and Czech market. On the other hand, despite long warranty, I would personally be cautious about any mainstream CWT-made unit. Real-world (not those from manufacturers/rebranders) statistics and user experience are on the lower side with these. Often customers are so irritated after several complains of CWT units (which are also often repeatedly given back as “good”) they just throw the unit away (so it stays with “sold” and “no RMA” status for the rebrander) and buy something else.

So be cautious that paper warranty is not everything and despite this long warranty, many series from different rebranders (for example Enermax NAXN, Corsair VS, VX and many more) already have quite bad reputation. Only time will tell if this mainstream DC-DC platform from CWT will have too. One of the reasons for many warranty complains are “poor quality in general” (Corsair quote) 400V C(r)apXon capacitors CWT uses in PFC circuitry. Remember what capacitor this unit uses?

So the evaluation for Cooler Masteer G550M as mainstream unit is as follows:

  • components used: 10 p. (− for bad capacitors, + for saver technology, + for second thermistor)
  • built quality: −5 p. (− for solder balls and messy soldering, − for loose wire)
  • voltage regulation: 5 p. (− for combined loading, − for crossloading)
  • ripple: 8 p. (− for combined loading, − for crossloading)
  • efficiency: 13.5 p. (+ for higher average efficiency, − for poor crossload efficiency)
  • hold-up time: 23 p. (+ for longer voltage hold-up time)
  • others: 18 p. (+ for working OPP, + for modular cabling, + for sleeved modular cables)


If we say the price is 2100 CZK, then the price per value ratio would be 100×72.5/2100 = 3.45. We will start comparing in a table with the next mainstream unit.

Pros + modular cabling
+ reasonable price
+ silent
+ good voltage hold-up time
+ all protections working
+ long warranty
Cons high operation temperatures esp. under high load
 poor −12 V voltage regulation
bad capacitors
sub-90% efficiency
Be aware of… /?\ overheating


I thank the Cooler Master company for providing the Cooler Master G550M unit.


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