Cooler Master MasterWatt 750 Watt Semi-Fanless 80 PLUS Bronze PSU Review
Cooler Master is well known for their affordable high-quality products and when others seek to maximize profit Cooler Master steadfastly maintains high-quality affordable products for the everyday person.
In this case, they sent us the Cooler Master MasterWatt 750 Watt Semi-Fanless 80 PLUS Bronze PSU to review and we’ve seen it peek its head out at $79.99 which is tough price point to fight for with many selections at 750W and in that same price point bracket. Often non-nerds overlook the need for a high-quality dependable PSU and end up with something on sale to save a few bucks but power supplies are probably the last place you should worry about scrimping on money. It is essential that the heart of your machine (the PSU) is high quality, dependable and sufficient size. Pick too small a PSU or the on sale $19 off brand low-quality PSU and you stand the chance of frying all that expensive hardware for the lack of a few bucks on a well-chosen PSU.
The CM (CM – Cooler Master) Master Watt Semi-fanless Modular 80 Plus Bronze power supply is named semi-fanless because at 15% load the fan remains off and ramps up as the power consumed increases. CM chose to call it Modular and indeed some of the wires are modular but it has a 20+4 pin motherboard and an 8-pin and 4-pin CPU power connectors that are hard-wired so semi-modular would be more appropriate. The PSU industry seems to have settled on Modular which has the 20+4 and the CPU power connectors hardwired and totally modular (which we prefer) where all the wires are removable.
We perused the specifications on the MasterWatt 750 Watt Semi-Fanless 80 PLUS Bronze and we have to say that Cooler Master is pushing it as an everyman’s PSU that doesn’t need the highest efficiency. Here’s the thing about higher efficiency PSU, as the efficiency increases so do the cost of higher efficiency components and manufacturing costs. So take a 1500W Gold PSU and typically they can run in the $400 range pushing 87 to 90% efficiency but at a greatly increased cost. Take our MasterWatt 750 Watt Semi-Fanless 80 PLUS Bronze and we run 82 – 85% but at $79.99 it’s just 5% less efficient hence the every man everyday PSU.
Features & Specifications
- Semi-Fanless up to 15% load – Experience noise-free operation in normal PC loads under 15% output.
- Dual Forward and DC-to-DC circuit design – The Dual Forward and DC-to-DC circuit design offers reliability and stability especially significant in +3.3V and +5V output.
- 5 years warranty – The MasterWatt comes with a 5-year warranty
- More Conductive PCI-e Cables – The MasterWatt uses 16AWG cables for PCI-e cables. Less resistance means better efficiency.
- 80 PLUS Bronze Certified – The 80 PLUS Bronze certification means MasterWatt is independently tested with efficiency of 85%.
- Durable LDB bearing – Silencio technology combines sealed LDB bearings with quiet fan blades delivering a long lifetime of quiet cooling.
With that 5-year warranty, Cooler Master is putting a lot of faith in their product and we would suspect that the MasterWatt we are looking at today will make that5-year mark easily.
We also like that they went with their Silencio fan that combines LDB bearing with IP6X dustproof certification. Here’s a quick rundown of the cooling setup.
- Sealant on the groove outside of the bearing helps to circulate the oil recycle slot adds extra storage space for the oil
- Sealant on the bobbin and featuring the highest dustproof level IP6X
- Recycle slot adds extra storage space for the oil
- The shaft makes the oil flow by pumping it while spinning
The shaft makes the oil flow by pumping it while spinning the Cooler Master 120mm Silencio FP fan combines sealed LDB bearings with quiet fan blades offering a long lifetime of quiet cooling.
Semi-Fanless up to 15% loadMasterWatt Operates at 0dB under 15% load. Experience noise-free basic computing.
The MasterWatt uses 16AWG cables for PCI-e cables. Less resistance and better efficiency, providing you a safer user environment.
The Dual Forward and DC-to-DC circuit design offers reliability and stability. This is especially significant in +3.3V and +5V outputs
Dual Forward and DC-to-DC Circuit Design.
.This is a graphic of the cable lengths and connectors on each cable. For a 750W PSU, this one has two 2 + 6-Pin PCIe cable with two connectors on it so you should be able to run most 2 GPU setups as long as they aren’t two massive power hungry cards. Two SATA cables with 4 connectors each, one 4-pin CPU cable, one 4 + 4 pin CPU cable and the 20 + 4 pin mainboard connector. Be sure and check your motherboard specifications to ensure you don’t need two 8-pin CPU power connectors.
Cables & Connectors
Here’s a graphic of the cable layout for those who prefer a table representation of cable layout.
Here’s a carton and package dimension table for bulk buyers and it will give you an idea of shipping weight.
The output rating shows a single large 12v rail capable of pushing 62.5 Amp and 750W, the +3.3 can handle 22A as does the +5V.
Packaging & Unboxing
Like most power supplies the MasterWatt 750 Watt Semi-Fanless 80 PLUS Bronze comes in a sturdy cardboard box with plenty of information on it.
The back of the box contains more information and efficiency profile and fan ramp noise diagram. We will be seeing more of those later.
Once we got inside the formidable box we found a manual, the PSU wrapped in a bubble bar type packing and the cables along with 4 screws.
This is something you don’t see often on one of the flaps we found the cable layout which is a nice addition for the consumer to help make a decision about buying the product.
Here’s that bubble bar wrapping we spoke of earlier it is quite durable and protective and our PSU arrived unscathed.
Then finally we come to the cables which are quite the surprise being flat ribbon cables which will earn some scoring points.
A Closer Look
The cable side of the MasterWatt 750 Watt Semi-Fanless 80 PLUS Bronze shows 5 open connectors, 3 for SATA/Molex and 2 for PCIe. These cable layouts being 5-pin are not the industry standard cable setup but it’s not that uncommon but keep track of your cables as these might be harder than traditional cable to find.
This side of the PSU shows the CM logo and that it’s a Masterwatt 750W PSU.
The rear of the PSU shows the honeycomb design determined as providing the maximum airflow some years back. The design provides more open space than previous round holes.
Here’s the power output schematic printed on the side of the MasterWatt 750 Watt Semi-Fanless 80 PLUS Bronze.
Moving around the PSU you can tell it has a matte black surface and during handling, proved to be finger print resistant.
The 120mm fan is one of CMs’ Silencio fans and during testing ran so quietly our 30dB decibel meter barely picked it up at the heaviest load.
The bottom of the PSU is completely unremarkable with no writing or stamped logo.
With the cables in front of the PSU you can see how large the 20+4 cable is and considering the other cables are flat we would have liked to have seen flat cables on the non-modular portions of the PSU.
Last but not least here’s an angled shot of the MasterWatt 750 Watt Semi-Fanless 80 PLUS Bronze and it’s a pretty good looking PSU but for $79.99 you aren’t getting RGB but you are getting a good solid PSU that will workhorse all day long.
- CPU: Intel Core i7-8700K
- Motherboard: ASRock Killer SLI
- RAM: 16GB Corsair 3733MHz
- GPU: EVGA GTX 1080 Ti SC2 ICX
- GPU: EVGA GTX 1080 Ti FTW3 ICX
- SSD: Kingston KC1000 480GB
- PSU: SilverStone SST-ST1500-GS
- Fans 3x Corsair ML120 Pro
- Cooling: EVGA CLC Cooling 240mm
- OS: Windows 10 Professional X64
We measure the voltage from the wall using a KillAWatt voltage measuring device then dissect each line with a multimeter. To jump-start the power supply you jump pins on the 24 pin power connector specifically 15 and 16 the green and black wires. The Jumpstart method is to test a PSU out of the box before connecting it too expensive hardware. This test can also be done with a dedicated PSU tester that’s fairly inexpensive.
Then there’s the tricky part where your machine is hooked to the PSU and you stress different components to achieve the voltage you want to test. We stress the CPU at stock speed, then OC the CPU to the maximum stable speed, read the voltage from the wall and made note of it, then the black probe goes into any black wire from the back of the 24 pin mainboard connector. The black wires are grounds and we can use the same one on all the tests. Then as we want to pull more voltage we can stress a single 1080 Ti and record the voltage and rerun the 12V test. We add a second 1080 Ti and stress both in SLI and finally we OC the SLI array and stress both with the CPU overclocked to the max and both 1080 Ti maxed out. That’s about as much voltage as you can pull without a synthetic load line tester.
You don’t just test the wires willy nilly, of course, there’s a set wire for each test and here’s a schematic of what wires do what when it comes to PSU testing.
Testing & Performance
We used a KillAwatt to get the voltage drawn from the wall and a Fluke 276 clamp meter with 18-inch flex current probe, we used a simple infrared thermometer to get the thermal exhaust and a Decibel Meter for noise.
With the Cooler Master MasterWatt 750W 80+ Bronze running at close to 25% load 185.92W from the wall we read 158.84W delivered from the PSU with 84.9% efficiency with a fan noise of 33.3dBA and a thermal exhaust of 40.19oC. The 12V rail was at 12.09V well within the 5% industry standard allowable variance.
Pushing the CM PSU close to 50% it maintained a 12.06V reading on the 12V rail and considering 12.6V is 5% variance that’s a pretty tight regulation. We were drawing 366.33W from the wall and delivering 309.76W from the PSU for an 84.56% efficiency with a fan noise of 33.3dBA and exhaust reading of 40.09oC.
Moving to a 61% load at 457.86W from the wall and delivering 393.75W and still reading a 12.06V on the 12V rail so we must have gotten a PSU with every good voltage regulation. We are running at 85.9% efficiency while the whisper quiet Silencio fan kept noise levels at 33.3dBA with an exhaust reading of 41.39oC.
Pulling 545.78W from the wall and a 12V rail reading of 12.05V and delivering 468.82W from the PSU we reached an efficiency of 85.89% with a slight increase in noise levels to 34.6dBA and the Cooler Master MasterWatt 750W 80+ Bronze certainly shows tight voltage regulation and efficiency hovered around 85%.
Final Thoughts & Conclusion
Throughout testing the Cooler Master MasterWatt 750W 80+ Bronze maintained tight voltage regulation while the Silencio cooling solution kept things whisper quiet. Suitable for a mid-range enthusiast computer the MasterWatt 750W should be good for running a well-stocked machine and even run a little SLI or X-Fire. The Cooler Master PSU provides a full suite of overvoltage and under voltage protection. Operating temperatures run from 0oC to 40oC and the current price runs $79.99 in a brutal market segment.
With high quality PSU popping up in the 750W range with similar prices the Cooler Master MasterWatt 750W 80+ Bronze faces stiff competition but the voltage regulation we saw and the better than 80+ Bronze certification efficiency the MasterWatt 750W is somewhat of a bargain running in the 85% efficiency range.
Pushing 62.5Amp across a single 12V rail the Cooler Master MasterWatt 750W 80+ Bronze should provide the reliable power you need at a price you can afford!
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