be quiet! Straight Power 12 1200W Report (Page 3 of 4)

Page 3 - Physical Look - Inside

As always, we opened up the be quiet! Straight Power 12 1200W power supply to take a detailed look at what is going on inside. Please note that doing this at home will void your 10-year warranty, thanks to the warranty seal be quiet! applied over the connecting edges between the two halves. For your benefit, we opened ours up, so you do not need to. There are no user serviceable parts inside.

Opening the be quiet! Straight Power 12 1200W is quite straightforward with the removal of four screws. Taking out the internal components from the enclosure requires the removal of even more screws, but most of the important parts can be found from this side. The OEM for this power supply is FSP Group. It features an LLC full bridge topology with DC-to-DC converters. At first glance, the build quality appears to be excellent. There are three main heatsinks inside with almost no wires inside. All of the heatsinks are located on the primary side.

Starting with the transient filter stage, there is a total of two X-capacitors and four Y-capacitors near or around the AC receptacle. This is two times the amount of X and Y capacitors than recommended. In addition, we have two common mode chokes and a metal oxide varistor. The MOV helps with suppressing voltage spikes. Considering some modern-day PSUs are missing MOVs, I am happy to see it here.

The active PFC circuit featured on the be quiet! Straight Power 12 1200W uses two Shindegen LL25XB60 bridge rectifiers on each side of a heatsink. At 115V, the maximum rectified forward current capacity with heatsink is 25A each, so you can theoretically pull up to 5750W (25A * 2 diodes * 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 the fact that not every component in the system is able to keep up.

Further down the line, we can see two active PFC MOSFETs, which are Infineon IPA60R080P7 power transistors. Each one is certified for up to 23A at 100c. These transistors present a typical resistance of 80 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. On the same heatsink, there are two Wolfspeed C3D08065I Schottky diodes. Just for some clarity, Wolfspeed is the new name of what was formerly known as Cree.

As for the primary capacitors, you can see a total of three Japanese brand ones from Nippon Chemi-Con. This be quiet! Straight Power 12 1200W power supply uses two 470µF x 420V and one 330uF x 420V for an equivalent capacitance of 1270µF x 420V. They are all rated at 105c, whereas more value-oriented power supplies usually use 85c rated capacitors. It is pretty neat to see a total of three primary capacitors, but this is something we have seen from higher capacity power supplies.

Finally, we have four switcher MOSFETs located on another heatsink near the primary capacitors, and these are the Infineon IPA60R120P7. Each of these are certified for up to 16A at 100c. These transistors present a maximum resistance of 120mΩ when turned on according to the manufacturer's data sheet.

On the secondary side, we can see more Japanese brand electrolytic capacitors from Rubycon rated at 105c. Unfortunately, I could not identify the manufacturers of the other polymer capacitors. One thing we should note is be quiet! states they only use Japanese capacitors rated at 105c. However, in our unit, we actually found two Taicon capacitors, which are made in Taiwan. While Taicon is a partnership with Nichicon, these are still Taiwanese capacitors. As such, be quiet! has not stuck to their claims of exclusively using Japanese capacitors here, which is unfortunate.

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 the power supply unit. A total of twelve Toshiba TPHR8504PL MOSFETs generate the +12V output, located on a daughterboard near the secondary side of the transformer. Its rated continuous drain current is 150A at 25c. It has an RDS(on) value of 0.85 mΩ maximum and 0.7mΩ typical at 10V.

On a different add-in board, we have the MOSFETs that generate the +5V and +3.3V output from the +12V rail. This includes six Infineon BSC0901NS MOSFETs. These act as the DC-to-DC converter. The BSC0901NS has a drain to source current of 94A at 100c, with an RDS(on) of 1.9mΩ and a typical resistance of 1.6 mΩ at 10V. Finally, an Anpec APW7159C can be found on the same daughterboard and is used for controlling the PWM switching.

Other components on other add-in boards include a Weltrend WT7527 monitoring IC, which provides overvoltage, undervoltage, and overcurrent protection, as well as the power good signal. The datasheets for all of the components mentioned in the inspection should be found on their respective manufacturer's website.

At the back, we have a large daughterboard covering the majority of the rear panel for the modular cable sockets. All modular sockets at the bottom are soldered directly to the main PCB after the secondary stage. Pin headers join the mainboard and daughterboard to reduce power transmission loss. The output connector configuration can be seen on the previous page.

Overall, the internal build quality of the be quiet! Straight Power 12 1200W power supply is excellent. Components are arranged very well for optimal cooling with almost no wires running around inside, and solder points on its black PCB is quite clean in general. Component choices here are also of good quality for this power output. The only thing that bothers me is the claim of exclusive Japanese capacitors when that is not the case. Regardless of how Taiwanese capacitors are perceived, the marketing claims were either not true or should have only specified certain capacitors.

Finally, there is a 135mm fan that provides cooling to the rest of the components of the be quiet! Straight Power 12 1200W. It is connected to the power supply with a 2-pin connector. A 135mm fan is only slightly smaller than a 140mm maximum you can fit in an ATX power supply, while still providing sufficient air movement to operate at lower speeds for a quieter overall operation.

The fan is a be quiet! Silent Wings BQ SIW3-13525-HF-26, as shown in our photo above. This is a fluid dynamic bearing fan with a 6-pole fan motor specified at 0.56A for a maximum of speed of 2600 RPM. There is no semi-fanless mode offered with the Straight Power 12 1200W, but the fan speed will change with the load of the power supply. Fans with fluid dynamic bearings generally have much longer lifespans compared to sleeve bearing fans, and are quite suitable for this application.

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