Rosewill Tachyon 750 W Power Supply Review
By Gabriel Torres on December 13, 2012
Rosewill offers four power supply models within their Tachyon series: 550 W, 650 W, 750 W, and 1,000 W. Today we are going to take a look at the 750 W version. Let’s check it out.
The Tachyon 750 W is a rebranded Super Flower SF-750P14PE, and therefore internally identical to the Kingwin Lazer Platinum 750 W and the AZZA Platinum 750 W. (The original model from Super Flower and the Kingwin model use connectors on the modular cabling system with LEDs that turn on when the power supply is in operation.)
The Rosewill Tachyon 750 W is 6.7” (170 mm) deep, using a 140 mm sleeve-bearing fan on its bottom (Globefan RL4ZS1402512HH). Differently from the AZZA Platinum 750 W, this unit doesn’t have a switch on its rear for you to select the mode in which you want the fan to work.
The modular cabling system from this power supply has six connectors. Differently from most power supplies with a modular cabling system, you can install any kind of cable in any connector, i.e., there is no specific connector for the video card power cables or for the peripheral and SATA power cables. The unit comes with the main motherboard cable, an ATX12V/EPS12V cable, one EPS12V cable, and one video card power cable permanently attached to it. They use nylon sleeves that come from inside the unit. This power supply comes with the following cables:
The wires for the ATX12V/EPS12V connectors are 16 AWG, i.e., thicker than the minimum recommended. All other wires are 18 AWG. The Tachyon 750 W has an additional EPS12V cable in comparison to the cable configuration of the AZZA Platinum 750 W. On the other hand, the model from AZZA uses 16 AWG wires on the video card cables that are permanently attached to the power supply, which doesn’t happen with the model from Rosewill.
Even though the number of connectors is satisfactory for a 750 W power supply, we think a high-end unit with the 80 Plus Platinum certification deserves more SATA connectors.
Let’s now take an in-depth look inside this power supply.
We decided to disassemble this power supply to see what it looks like inside, how it is designed, and what components are used. Please read our “Anatomy of Switching Power Supplies” tutorial to understand how a power supply works and to compare this power supply to others.
On this page we will have an overall look, and then in the following pages we will discuss in detail the quality and ratings of the components used.
As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality, is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components, usually removing the MOV and the first coil.
In the transient filtering stage, this power supply has two X capacitors and two Y capacitors more than the minimum required, but it doesn’t have an MOV, which is the component in charge of removing spikes coming from the power grid.
On the next page, we will have a more detailed discussion about the components used in the Rosewill Tachyon 750 W.
On this page, we will take an in-depth look at the primary stage of the Rosewill Tachyon 750 W. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.
This power supply uses one US30K80R rectifying bridge, which is attached, at the same time, to an individual heatsink and to the heatsink where the active PFC and switching transistors are attached. This bridge supports up to 30 A at 97° C. In theory, you would be able to pull up to 3,450 W from a 115 V power grid. Assuming 80% efficiency, the bridge would allow this unit to deliver up to 2,760 W without burning itself out (or 3,105 W at 90% efficiency). Of course, we are only talking about this particular component. The real limit will depend on all the components combined in this power supply.
The active PFC circuit uses two IPP50R199CP MOSFETs, each one supporting up to 17 A at 25° C or 11 A at 100° C in continuous mode (note the difference temperature makes), or 40 A at 25° C in pulse mode. These transistors present a 199 mΩ maximum resistance when turned on, a characteristic called RDS(on). The lower the number the better, meaning that the transistor will waste less power, and the power supply will have a higher efficiency.
The active PFC circuit is managed by an NCP1653A active PFC controller.
The output of the active PFC circuit is filtered by a 560 µF x 400 V Japanese electrolytic capacitor, from Chemi-Con, labeled at 105° C.
In the switching section, two IPP50R140CP MOSFETs are employed using a resonant configuration. Each transistor supports up to 23 A at 25° C or 15 A at 100° C in continuous mode, or 56 A at 25° C in pulse mode, with a maximum RDS(on) of 140 mΩ.
The switching transistors are controlled by an SF29601 controller, but we couldn’t find more information about this chip. We believe that the original manufacturer got a resonant controller and relabeled it, as SF stands for “Super Flower.” Interestingly enough, the controller is placed in the secondary of the power supply.
Let’s now take a look at the secondary of this power supply.
As one would expect in a high-efficiency power supply, the Rosewill Tachyon 750 W uses a synchronous design, where the Schottky rectifiers are replaced with MOSFETs. Also, the reviewed product uses a DC-DC design in its secondary. This means that the power supply is basically a +12 V unit, with the +5 V and +3.3 V outputs produced by two smaller power supplies connected to the main +12 V rail. Both designs are used to increase efficiency.
The +12 V output uses four IPP041N04N G MOSFETs, each one supporting up to 80 A at 100° C in continuous mode and up to 400 A at 25° C in pulse mode, with a maximum RDS(on) of 4.1 mΩ. Strangely, the AZZA Platinum 750 W uses different transistors here (IPP023N04N G, supporting up to 90 A at 100° C in continuous mode and up to 400 A at 25° C in pulse mode, with a maximum resistance of only 2.3 mΩ).
As explained, the +5 V and +3.3 V outputs are produced by two DC-DC converters, which are situated on a single printed circuit board located in the secondary section of the power supply. Each converter is controlled by one NCP1587A integrated circuit and uses two IPD060N03L MOSFETS, each supporting up to 50 A at 100° in continuous mode and up to 350 A at 25° C in pulse mode, with a maximum RDS(on) of 6 mΩ. On the AZZA Platinum 750 W, each output uses four IPD040N03L MOSFETs, each supporting up to 76 A at 100° C in continuous mode and up to 400 A at 25° C in pulse mode, with a maximum RDS(on) of 4 mΩ.
We didn’t see an integrated circuit for monitoring the power supply outputs. Since the Power Good wire and sensors were connected to the small printed circuit board where the resonant controller was attached, our best guess is that the enigmatic SF29601 controller, with the aid of four operational amplifiers provided by an LM324 integrated circuit, did the trick.
The electrolytic capacitors available in the secondary are also Japanese, from Chemi-Con, and labeled at 105° C, as usual.
The +5VSB (a.k.a. standby) power supply is independent of the main power supply, since it is on continuously.
The +5VSB power supply uses an ICE3B0565 integrated circuit, which incorporates the PWM controller and the switching transistor into a single chip.
The rectification of the +5VSB output is performed by a PFR40V60CT Schottky rectifier, which supports up to 40 A (20 A per internal diode at 110° C, 0.55 V maximum voltage drop).
In Figure 21, you can see the power supply label containing all the power specs.
This unit has a single +12 V rail, so there is not much to talk about here.
How much power can this unit really deliver? Let’s check it out.
We conducted several tests with this power supply, as described in the article, “Hardware Secrets Power Supply Test Methodology.”
First, we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching the behavior of the reviewed unit under each load. In the table below, we list the load patterns we used and the results for each load.
If you add all the powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (e.g., the +5 V output working at 5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. In the “Total” row, we are using the real amount of power being delivered, as measured by our load tester.
The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During this test, the +12VA and +12VB inputs were connected to the power supply single +12 V rail. (The +12VB input was connected to the power supply EPS12V connector.)
5.5 A (66 W)
11.5 A (138 W)
17 A (204 W)
22.5 A (270 W)
27.5 A (330 W)
5.5 A (66 W)
11 A (132 W)
16.5 A (198 W)
22 A (264 W)
27.25 A (327 W)
1 A (5 W)
2 A (10 W)
4 A (20 W)
6 A (30 W)
8 A (40 W)
1 A (3.3 W)
2 A (6.6 W)
4 A (13.2 W)
6 A (19.8 W)
8 A (26.4 W)
1 A (5 W)
1.5 A (7.5 W)
2 A (10 W)
2.5 A (12.5 W)
3 A (15 W)
0.5 A (6 W)
0.5 A (6 W)
0.5 A (6 W)
0.5 A (6 W)
0.5 A (6 W)
% Max Load
Ripple and Noise
The 80 Plus Platinum certification promises efficiency of at least 90% under light (i.e., 20%) load, 92% under typical (i.e., 50%) load, and 89% under full (i.e., 100%) load. The Rosewill Tachyon 750 W matched these numbers, except during the full load test, in which it presented 88.3% efficiency. However, we have to consider that we tested this power supply at almost 50° C, while the 80 Plus certification tests are conducted at 23° C, and efficiency drops as temperature increases. Another explanation for the lower efficiency is because of the AC voltage, which was below 115 V during this particular test. On the other hand, we have excellent efficiency numbers for the other tests, in particular at light load, where we saw 91% efficiency.
Let’s discuss voltage regulation on the next page.
The ATX12V specification states that positive voltages must be within 5% of their nominal values, and negative voltages must be within 10% of their nominal values. We consider a power supply as “flawless” if it shows voltages within 3% of its nominal values. In the table below, you can see the power supply voltages during our tests and, in the following table, the deviation, in percentage, of their nominal values.
The Rosewill Tachyon 750 W presented very good voltage regulation, with all its main positive voltages within 3% of their nominal values.
Let’s discuss the ripple and noise levels on the next page.
Voltages at the power supply outputs must be as “clean” as possible, with no noise or oscillation (also known as “ripple”). The maximum ripple and noise levels allowed are 120 mV for +12 V and -12 V outputs, and 50 mV for +5 V, +3.3 V and +5VSB outputs. All values are peak-to-peak figures. We consider a power supply as being top-notch if it can produce half or less of the maximum allowed ripple and noise levels.
The Rosewill Tachyon 750 W provided extremely low ripple and noise levels, as you can see in the table below.
Below you can see the waveforms of the outputs during test five.
Let’s see if we can pull more than 750 W from this unit.
Below you can see the maximum we could pull from this power supply. The objective of this test is to see if the power supply has its protection circuits working properly. This unit passed this test, since it shut down when we tried to pull more than what is listed below. During this test, noise and ripple levels were still extremely low. The +12 V voltages dropped, but were still inside the allowed range.
31 A (372 W)
31 A (372 W)
13 A (65 W)
13 A (42.9 W)
3 A (15 W)
0.5 A (6 W)
% Max Load
The main specifications for the Rosewill Tachyon 750 W power supply include:
The Rosewill Tachyon 750 W is a very good power supply with the 80 Plus Platinum certification, with efficiency between 88.3 % and 92.1% during our tests, voltages closer to their nominal values than required (3% voltage regulation), and extremely low noise and ripple levels.
It comes with the same price tag as its main competitors, the AZZA Platinum 750 W and the Kingwin Lazer Platinum 750 W, which are based on the same platform.
Even though the Rosewill Tachyon 750 W is a very good power supply, the new Corsair AX760 is technically superior and costs the same, being our recommendation if you have USD 180 to spend on a power supply.