Rosewill Tachyon 650W PSU - Introduction

Even though Rosewill started off as an in-house brand of Newegg, the company evolved into a fully-fledged manufacturer and exporter. Today Rosewill's products may not only be found all over the US but in several other countries as well, in both America and Asia.

As Rosewill used to be an in-house brand, it carries the "stigma" of being a supplier of rebranded products and, as is usually the case with in-house brands, that these were of mediocre to low quality. With their separation from Newegg however and their evolvement to a stand-alone company and manufacturer, Rosewill broke free of the shackles usually imposed to subsidiary companies and is today capable of offering all kinds of products, from cheap everyday items to high performance power supplies. But where the Tachyon power supply lands on?

The Rosewill Tachyon 650W

On paper, the Tachyon is a very interesting product. It received an 80Plus Platinum certification, the highest a consumer power supply has ever achieved up to this date, the electrical specifications of the unit are very interesting, it is rated for operation at 50°C and it also is a semi-modular design; a good number of features for the $110.99 price (after rebate) at which the 650W version of the Tachyon currently retails at. It is however a good deal more expensive that competitive products, especially those rated at 80Plus Gold or Silver. It remains to be seen whether the performance of the Tachyon is enough to convince hardcore enthusiasts to pay the premium price for it.

Tachyon's modular connectors

Rosewill Tachyon 650W PSU features

Rosewill Tachyon 650W PSU specifications






ATX12V v2.31 & EPS12V v2.92

Maximum Power

Continuous 650W@50°C


1 x Silent 140mm



Main Connector


+12V Rails


PCI-E Connectors

4 x 6+2-pin

Modular Cabling Support


SLI Support


Power Good Signal


Hold-up Time

> 16ms


> 87%, Up to 92%

Over Voltage Protection


Overload Protection


Input Voltage

100 - 240 V

Input Frequency Range

47 - 63 Hz

Input Current









100k hours at 25°C, max. load, nominal input




5.9 x 3.39 x 6.7 inch 
150 x 86 x 170 mm 
W x H x D


2.7 kg
5.95 lbs


5-year One-to-One Replacement

Unboxing the Tachyon 650W

The box

We received the 650W version of the Tachyon in a typical cardboard box. Inside the box the power supply is well packed and protected by polyethylene foam pieces. The artwork is relatively simple and serious, with Rosewill obviously trying to create a professional look.

The box (rear)

The rear of the box holds the list of features, the number of connectors and the electrical specifications of all four models of the Tachyon series, not only of the 650W version which is inside the box.

Bundled items

Rosewill usually keeps their bundles down to a minimum, even with their high end products. With the Tachyon the company also provides a set of four black thumbscrews and a few cable ties alongside with the standard A/C cable and 3M mounting screws, which are a welcome addition, yet we would like to see at least a few cable straps provided with such a high-end product.

 Modular cables

As this is a semi-modular design, Rosewill provides the modular cables inside a small nylon bag. The cables are pretty standard, using color-coded wires and black sleeving. This power supply offers the following number of connectors:

Native cables

One 20+4pin ATX

One 4+4 pin ATX12V/EPS12V

Two PCI-E 6+2 pin

Modular cables

Two PCI-E 6+2 pin

Eight SATA connectors

Eight Molex connectors

One Floppy connector

External Design of the Tachyon 650W

The Rosewill Tachyon 650W PSU

Rosewill is using a steel chassis for the Tachyon, which the company sprayed all black. The chassis is 170mm deep, just a little longer than what the ATX design guide specifies; therefore it should fit inside almost every case with only very tight HTPC cases and special designs being the exception. The top cover of the power supply has been traded for one with an integrated honeycomb design fan cover.

Chassis sides

There are no logos, stickers or distinctive visual features anywhere about the power supply, not even over the motor of the fan, with the exception of the sticker with the electrical specifications at the top side of the unit. The sides of the Tachyon are entirely plain and all black.

Top side sticker

At the top of the power supply we found the only stickers of the power supply, one with the electrical specifications of the unit and one indicating that it is being covered by US registered patents. Patent 7,133,293 refers to the design of modular power supplies and patent D601,648 to the design of…baseball bats, which most likely is a typographical error on the sticker.

Rear Side

The six modular connectors of the Tachyon 650W power supply can be seen at the rear side of the chassis, each of them covered with a rubber cap. There is no legend but all six connectors are identical, allowing the connection of any cable to any connector.

Front Side

Much like any other modern power supply, the front side of the Tachyon 650W unit had to be perforated for the warm air to escape to the outside of the case. For that purpose, the company went with a large aperture honeycomb design. There is also a standard on/off switch.


A look inside the Tachyon 650W

The cooling fan

The 140mm fan inside the Tachyon 650W power supply has been rebranded by Rosewill but from the part number we identified it as the RL4Z S1402512HH fan by Globe, a rather rare fan with a sleeve bearing and a very high top speed. The S1402512HH can go as fast as 1800RPM, an extremely high speed for a 140mm fan, which is why the selection of this particular model for the cooling of an 80Plus Platinum unit is a very peculiar choice.

Inside the Rosewill Tachyon 650W unit

Rosewill chose Super Flower Computer Inc to be the OEM behind the 650W version of the Tachyon. Super flower is a reputable Taiwanese designer and manufacturer of computer power supplies and also is the OEM behind most of Rosewill's PSUs today. The very design of the Tachyon 650W unit is an upgraded version of the platform we encountered in the Capstone 750W a few months ago, allowing it to achieve 80Plus Platinum efficiency levels and greater overall performance.

The filtering and rectifying stages

The filtering stage of this power supply starts directly on the PCB, without any parts at the back of the A/C cable receptacle. On the PCB however there were four Y capacitors, three X capacitors and two filtering chokes. Although these are more parts than required for a standard transient filter, we were unable to locate a MOV. Metal Oxide Varistors (MOVs) are being used for surge suppression, the functions of which have been largely replaced by the active PFC circuits; however, this could still indicate that this unit's tolerance against lighting and or switching surges is limited.

Primary side

We found the primary rectifying bridge attached on an extended portion of the large heatsink holding the active PFC transistors and the two switching inversion transistors which form a resonant half-bridge configuration. A Nippon Chemi-Con 470um/400V 105°C capacitor takes care of the APFC filtering.

Secondary side

The large heatsink on the secondary side holds the rectifying transistors which generate the 12V rail. The minor rails are being derived from the 12V rail via DC to DC conversion circuits, found on a daughterboard right next to the heatsink. The metallic shields over the DC to DC conversion circuit transistors are to block interference and assist in cooling. The electrolytic capacitors on the secondary side are provided by Nippon Chemi-Con as well. 

Test Setup

The load

In order to be able to effectively and efficiently test any computer power supply unit, we developed and constructed our own proprietary testing station. Our testing station consists of a number of power resistors and small capacitors, which in turn are connected to a RS485 electronic relay array which allow our load to be controlled through computer software alone.

USB interface and connection panel

When accuracy and speed are of critical importance, a simple multimeter or voltage meter is not sufficient for the task. To ensure the quality of our testing, an USB laboratory interface is being used to continuously monitor and record the readings of all voltage lines simultaneously. For ripple measurements, an oscilloscope is necessary and we chose the USB Instruments Stingray, the most widely used oscilloscope amongst low voltage PSU engineers and testers.

Measurement instruments

For accurate testing and repeatable results, a stable power input is also required. Thus, we are providing power to our test samples through a 3kVA VARIAC which allows us to control the input voltage of our test samples and also perform efficiency tests under both 110V AC and 230V AC input. A Lutron DW-6091 is also being used, monitoring the input voltage, real and apparent power, power factor and amperage.

The software

A power supply testing procedure would not be complete without thermal and acoustics tests. For our acoustics tests we are using a SL-5868P digital sound level meter, placed 1 meter away from the unit (DIN standard). Two PT100 sensors and their respective displays are being used to monitor the ambient temperature and the exhaust temperature of the unit.

Complete test setup during trial run


Testing results (Regulation & Ripple)


The electrical performance of the Rosewill Tachyon 650W power supply was better than we initially expected. The voltage regulation on all lines is about 1.6%, very good by today's standards. Ripple suppression is very good as well, with the largest voltage ripple we recorded being 38mV on the 12V line under maximum load.

Testing results (Efficiency, Noise & Thermal)

Even though the Tachyon 650W power supply is 80Plus Platinum certified, our test sample barely managed to reach the minimum figures required by it and only while the power supply was being powered by an 110VAC source. The efficiency is very high by all means, staying over 89% under any circumstances, yet nothing special for an 80Plus Platinum power supply.

The operating temperatures of the Tachyon 650W power supply are very low, with the power supply barely reaching a delta of 6.5°C under maximum load. This is due to the high efficiency and, as seen in the following paragraph, the aggressive cooling profile of the power supply.

Acoustically, the Tachyon 650W power supply performs mediocrely, mostly because of the aggressive cooling profile which the thermal controller is programmed to follow. The power supply is silent at low loads but every load increase while the unit operates above 40% capacity will cause a disproportionate increase in fan speed, making the fan's noise audible at 50% load and loud at 70% load. 

Rosewill Tachyon 650W PSU - Conclusion

The Tachyon series is currently the best which Rosewill offers, boasting a modular design, 80Plus Platinum certification, ratings at 50°C, excellent quality and performance. Super Flower's expertise helped Rosewill a lot with that, delivering products which can really compete in the high-end segment of the market.

The overall performance of the Tachyon 650W power supply is very good. We could even dare saying that it was much better than we initially expected, considering that Rosewill is an infant when it comes to high performance products aiming towards hardcore enthusiasts. Nevertheless, the Tachyon 650W unit displayed excellent electrical performance, maintaining a tight voltage regulation and offering very good ripple suppression. Furthermore, the efficiency of the Tachyon 650W does meet the 80Plus Platinum certification levels just like Rosewill advertises, even if only barely. The running temperatures are very low, something which will especially please overclockers. Only the acoustics of the Tachyon 650W unit are average, with the power supply running silent only when lightly loaded.

The Rosewill Tachyon 650W

Design-wise, the appearance of the Tachyon 650W is simplistic but that is not necessarily a bad thing; on the contrary, we think that many modders will like its all-black design more than fancy engravings and stickers. The semi-modular design adds a lot of points, although the color-coded wires and standard cables are quite ordinary and perhaps even unsuitable for a product of this league.

Super Flower Design of Tachyon

Rosewill is a brand which usually is aiming towards maximum value for money. Value for money is a very relative term when it comes to high-end and extreme performance products, categories where the very definition of "value" is very fuzzy. We found the Tachyon 650W power supply retailing for $110.99 inc shipping after rebate at the time of this review, a very reasonable and competitive price for an 80Plus Platinum certified product. On the other hand, those not thrilled by the 80Plus Platinum certification and are willing to settle for 80Plus Gold/Silver products, they can find equivalent products for as much as 40% less. Rosewill's own Capstone 650W unit, which is based on a similar platform and is an 80Plus Gold certified product, can currently be bought for $78.49 inc shipping after rebate, the value for money of which is definitely better. But for those wanting the best possible performance and efficiency and are unwilling to settle for anything less than an 80Plus Platinum power supply, the Tachyon remains one of the most competitive products in that league.

Recommended Award


Legit Bottom Line: The Rosewill Tachyon 650W is a power supply balanced very well between high performance, good quality, decent design and value for money. If what you need is a reliable 80Plus Platinum power supply with good overall performance and do not want to break the bank, then the Tachyon should be among the first places of your shortlist.