be quiet! Pure Power 11 FM 750W Report (Page 3 of 4)

Page 3 - Physical Look - Inside

As always, we opened up our be quiet! Pure Power 11 FM 750W power supply to take a detailed look at what is going on inside. Please note that doing this at home may void your 5-year warranty thanks to a seal that extends over one edge of the power supply. But for the benefit of you, we cracked ours open so you do not need to, haha. There are no user serviceable parts inside.

Disassembling the be quiet! Pure Power 11 FM 750W is quite straightforward with the removal of four screws next to the fan mount. Our photo above shows an overhead view of its internal components. Its OEM is Channel Well Technology or CWT, a reputable OEM since 1993. At first glance, the build quality appears to be excellent. There are three main heatsinks inside.

Pulling the enclosure apart and we got straight to the internal inspection. The transient filter stage is the first input stage of a computer power supply, so we will take a look at that first. CWT has always done a great job in the past to make sure their power supplies met or exceeded the recommended requirements, and the be quiet! Pure Power 11 FM 750W is no exception. The be quiet! Pure Power 11 FM 750W has one metal oxide varistor, two metalized polyester X-capacitors, four ceramic Y-capacitors, and two ferrite coils. This is two times the amount of X and Y capacitors than recommended.

On the primary side, we can see two Taiwanese-made Teapo capacitors. Japanese brand capacitors are not specified on the marketing material, and as you will see, you will not find any Japanese brand capacitors in this power supply. Our 750W version of be quiet!'s Pure Power 11 FM series power supply incorporates two 390µF x 400V capacitors in parallel for a total of 780µF capacitance. They are rated at 85c; whereas most high-quality power supplies use 105c-rated capacitors. I was surprised not only did the company use Teapo for their bulk capacitors, but also the fact 85c-rated ones are found. That said, the Pure Power 11 FM 750W is priced competitively for a fully modular 80 Plus Gold unit, so the money savings have to come from somewhere, haha.

The active PFC circuit featured on the be quiet! Pure Power 11 FM 750W uses one Diodes Incorporated GBJ1506 bridge rectifiers attached to the first heatsink. At 115V, the maximum rectified forward current capacity with heatsink is 15A each, so you can theoretically pull up to 1725W (15A * 1 diode * 115V) from the bridge rectifier at 100% efficiency. Of course, this is limited by the fact that it is not 100% efficient, and also neglects not every component in the system are able to keep up. Further down the line, on the outside of the largest heatsink, we can see two ON Semiconductor FCPF165N65S3L1 MOSFETs. Each is certified for up to 12.3A at 100c. These transistors present a maximum resistance of 165 mΩ when turned on according to the manufacturer's data sheet. This on characteristic is called Static Drain-Source On-Resistance, or commonly abbreviated as RDS(on). The more efficient the component is, the lower the RDS(on) value, since it wastes less power with lower resistance. An ON Semiconductor FFSP0865A boost diode is placed right next them. Two ON Semiconductor FCPF190N60E MOFSETs, located on the smaller heatsink next to the largest heatsink, are used as the main switchers on the Pure Power 11 FM 750W power supply. Each is certified for up to 13.1A at 100c and maximum resistance of 190 mΩ.

Other components that can be spotted on the primary side include a Champion CM6500UNX on an add-in board and a Champion U6901VAC SLS, SRC/LLC + SR resonant controller on another add-in board.

On the secondary side, we can see more Teapo capacitors, but they are rated at 105c. All rectifiers produce the +12V out, while the +5V and +3.3V outputs are generated from the +12V output using a DC-to-DC converter within as with modern high efficiency power supplies. Six ON Semiconductor NTMFS5C430N power MOSFETs are responsible for generating the +12V output, located on an add-in board next to the transformer. The NTMFS5C430N's rated continuous drain current is 131A at 100c. It has an RDS(on) value of 1.7 mΩ maximum and 1.4 mΩ typical at 25c. Two UBIQ Semiconductor QM3054M6 and two UBIQ Semiconductor QN3107M6N fast switching MOSFETs on yet another add-in board generate the +5V and +3.3V output from the +12V rail. The QM3054M6's rated continuous drain current is 61A at 100c. It has an RDS(on) value of 4.8 mΩ maximum and 3.8 mΩ typical. The QN3107M6N's rated continuous drain current is 70A at 100c. It has an RDS(on) value of 2.6 mΩ maximum and 2.1 mΩ typical. uPI Semi's uP3861P, located on the same add-in board, is the PWM switching controller. Meanwhile, a Weltrend WT7527RT monitoring IC at the bottom of the PCB provides over current and over/under voltage protection. The datasheets for all components mentioned in this review can be found on their respective manufacturer's websites.

Other components that can be spotted include the Sync Power SPN5003 and SPN3006 N-Channel enhancement mode MOSFETs.

At the back, we have a large daughterboard covering the entire rear panel for the modular cable sockets. All modular sockets at the bottom are soldered directly to the main PCB after the secondary stage to reduce power transmission loss. The output connector configuration can be seen on the previous page. Overall, the internal build quality of be quiet!'s Pure Power 11 FM 750W is very good. Components are arranged very well for optimal cooling with practically no wires running around inside, and solder points on its black PCB is very clean. I would say the be quiet! Pure Power 11 FM 750W is generally good with regards to the selection of components used under the hood; appropriate for its performance class.

Lastly, we see a 120mm fan that provides cooling to the be quiet! Pure Power 11 FM 750W's internal components. It is connected to an add-in board using a 2-pin connector. A 120mm fan is rather small nowadays for a power supply with a bottom mounted fan, but if not a lot of heat is being generated, it should not be much of an issue. The fan is a be quiet! BQ QF2-12025-MS, as shown in our photo above. The BQ QF2-12025-MS is a rifle bearing fan specified at 0.20A for a maximum of speed of 1800 RPM. Fans with rifle bearings are quiet and have much longer lifespans compared to sleeve bearing fans and is quite suitable for this application.

Page Index
1. Introduction, Packaging, Specifications
2. Physical Look - Outside
3. Physical Look - Inside
4. Minor Tests and Conclusion