maximum efficiency / Enclosures, PSU and cooling

maximum efficiency / Enclosures, PSU and cooling


Among the representatives of the most advanced series of power supplies Seasonic PRIME TX are models with power from 650 to 1000 watts. Of course, they have the familiar advantages of the previously considered units of the FOCUS GX and PX series in the form of a dual-mode cooling system, but they surpass them in terms of efficiency and manufacturer’s warranty. However, it did not work to fit the stuffing of these models into the standard-size case: the power supplies of the PRIME series have a length of 170 mm, which is 30 mm longer than the models of the FOCUS series.

Differences in electrical and acoustic parameters will show practical testing.

⇡ #Packaging, scope of delivery, appearance

The packaging of the Seasonic PRIME TX-750 differs from the “Focus” container in both large dimensions and a more effective glossy finish, although the design style as a whole is close to what we have already seen.

The facade includes the manufacturer’s names, series and models, the 80 PLUS Titanium certification badge and features such as a fully modular cable system, hybrid fan control and a record-breaking 12-year warranty.

On one of the sidewalls there are tables with electrical parameters of the model and available cables and connectors.

The back part is divided into two halves: the first is devoted to the efficiency of the model (efficiency chart in 115 and 230 V networks, the accuracy of voltage regulation within 0.5% over the entire load range), and the second to the cooling system (description of the hybrid mode operation algorithm and relative level noise at various loads – at maximum speeds the declared noise is only slightly higher than the background noise at the recording studio).

The delivery set is very similar to what we saw with the models of the FOCUS series. It also includes multilingual printed instructions, an installation guide, an offer to register a product with a chance to win $ 50 for buying games on Steam, a tester to check the PSU’s functionality without being installed in the case, and a set of fasteners supplemented with disposable and reusable cable ties. The differences boil down to the fact that the printed instruction is framed differently, and a sticker has been added to the kit on the body of the system unit.

The power supply and removable cables are packed in bags made of velvety fabric that looks much more effective and reliable than the nondescript synthetics of power supplies of the FOCUS series.

The power supply case has dimensions of 170 × 150 × 86 mm, which may upset the owners of compact cases. The cable system – and this is expected for a block of this class – is fully modular.

The exterior design is even more spectacular than that of the FOCUS series models: side faces with curly cuts, a two-color ventilation grille with elongated hexagonal cells, expressive inserts on the sides and top with the name of the PRIME series.

The set of connectors for connecting cables has become more extensive than that of models of the FOCUS line of the same power: six connectors are available for CPU / PCI-E power cables and five for SATA / Molex power cables (FOCUS models offered four connectors of each type).

The back panel is taken up by a ventilation grill with cells of the same shape as on the top panel. It contains the input of the power cord, power switch and button for selecting the operating mode of the cooling system. At the bottom of the case there is a sticker with information about the model, including input and output electrical parameters.

⇡ #Specifications

Manufacturer Seasonic
Model PRIME TX-750 (SSR-750TR)
Cable connection Fully modular
Maximum load power, W 750
80 PLUS Certification Titanium
ATX Version ATX12V 2.3
Power Options 100-240 V, 9.5-4.5 A, 50-60 Hz
Efficiency > 94%
Pfc Active
Load protection OVP (Over Voltage Protection)
OPP (Over Power Protection)
OCP (over current protection)
UVP (undervoltage protection)
OTP (temperature protection)
SCP (short circuit protection)
Dimensions, mm 170 × 150 × 86
Weight kg Nd
MTBF (MTBF), h 150,000 at 25 ° C (50,000 at 40 ° C for fan)
Warranty period, years 12
Estimated retail price, rub. 18 000

A table with electrical parameters, located at the bottom of the power supply, reports that out of 750 W of the total output power, 744 W can be directed at a voltage of 12 V. The permissible total load on the 3.3 and 5 V lines is 100 W, which is enough stock for any modern system. Standby power allows a load of up to 3 A.

For the unit, continuous operation is guaranteed at 100% of the output power at an ambient temperature from 0 to 40 ° C and at 80% power – from 40 to 50 ° C.

All of the above parameters completely coincide with the indicators of the 750-watt Focuses already familiar to us. Among the differences is the certification level of 80 PLUS Titanium and a two-year longer manufacturer’s warranty (12 years against 10).

Let us dwell separately on the features of voltage stabilization declared for blocks of the PRIME series. Only a mention of the accuracy of regulation of 0.5% is made on the box thanks to MTLR technology (Micro Tolerance Load Regulation). However, a closer examination of the documentation makes it clear that this applies only to voltage deviations when the load changes, while the “basic” level of deviations can be up to ± 1% of the nominal value for lines 3.3 and 5 V and up to +2% for voltage of 12 V (which, however, is also an excellent indicator).

⇡ #Cables

The cable system fully complies with modern requirements both in the range of available connectors (which many higher power models will envy) and in the length of the wires.

Set of power connectors:

  • 1 × 20 + 4 pins;
  • 2 × ATX12V (4 + 4 pins) – CPU power;
  • 4 × 6 + 2 pins – additional power for PCIe cards;
  • 10 × SATA;
  • 5 × Molex;
  • Molex to 2 × SATA adapter.

It is worth noting that, unlike the models of the FOCUS series, PRIME cables with PCI-E power connectors are made exclusively single – without options with two connectors on one cable.

Like the updated models of the FOCUS series, on the updated blocks of the PRIME series, the main power cable is made in a nylon braid, and all the others have a flat design.

All wires are typical 18 AWG.

⇡ #Design, internal arrangement

The internal components are cooled by a 135mm HongHua HA13525H12F-Z fan based on a hydrodynamic bearing. The nominal fan speed is 2300 rpm.

Note that in the early-release Seasonic PRIME Titanium power supplies that I had to deal with, the slower modification of the HA13525M12F-Z fan (1800 rpm) was used.

The internal device demonstrates the familiar layout of the Seasonic PRIME platform (among the models we reviewed, the ASUS ROG Thor 1200W Platinum power supply is based on the modified “platinum” version of this platform).

Accordingly, we have before us a modern platform based on the LLC resonant topology with individual voltage stabilization and active power factor correction.

A board with DC / DC converters is located between the panel of modular connectors and the daughter board with a cooling controller. Also in the photo you can see smoothing solid-state capacitors on a board with modular connectors.

Another daughter board with an SRC / LLC + SR Champion Micro CM6901 controller chip is located behind the board that regulates the operation of the cooling system.

A Weltrend WT7527V supervisor chip is placed on the daughter board along the side of the chassis

The input filter on the main circuit board includes a completely typical set of two common-mode chokes, a CX capacitor, four CY capacitors and a varistor.

Also, filter elements are also available under the screen at the input of the power cord: there are placed a pair of capacitors CX and CY, as well as a fuse.

Two electrolytic capacitors manufactured by the Japanese company Rubycon with a total capacity of 1030 uF are used at the input. An empirically excellent result is the capacity of the input capacitors in microfarads, numerically equal to the output power in watts – and this level in PRIME TX is noticeably surpassed.

The output uses electrolytic capacitors manufactured by Rubycon and Nichicon, as well as solid-state capacitors hidden under the cooling radiator.

In general, as expected, there is not the slightest complaint about the components used or the build quality.

⇡ #Testing methodology

The testing methodology adopted by 3DNews is described in a separate article, which is recommended for reading to understand the operation of computer power supplies and their most important characteristics. Please contact her to find out why you need and how this or that component mentioned in the review works, and how to interpret the test results.

⇡ #Test results

The Seasonic PRIME TX-750 efficiency measured during the test shows expected high results.

In part, such high indicators are a consequence of the measurement error of the household wattmeter, which underestimates the power “from the outlet” at medium and heavy loads.

Closer to the actual performance values ​​will be the results of the 80 PLUS certification report for the Seasonic SSR-750TR (at 10/20/50/100% of the power, the efficiency was fixed at 91.71 / 93.85 / 94.59 / 92.89%, respectively). These results were obtained in a 115 V power supply network, so that in a 230 V network, the efficiency should be higher.

According to the schedule from the manufacturer, in a 230 V network, the unit gains a very impressive bonus to efficiency: at full power, the efficiency is comparable to the peak in the network of 115 V, and in the peak it exceeds 97%.

In comparison with the models of the FOCUS series, a significantly higher starting speed of the cooling fan (over 800 rpm) can be noted, which is compensated by its preservation to almost full power. Under full load, the impeller speed only slightly exceeded 900 rpm.

When the hybrid cooling mode was activated, the start of the fan was noted only after reaching 70% of power. At this point and further, the impeller rotation speed was almost the same in both modes of operation of the cooling system. However, there was a fly in the ointment: when the fan starts (both when the power supply is turned on and when the fan is activated after inactivity in hybrid mode), it initially starts at full speed, and for a second or two it turns out to be quite audible.

Although during the testing we did not notice the frequent on / off of the fan in hybrid mode, just in case we would stop at the cooling system with the fan constantly on – it is practically inaudible at any load.

Although the cross-load characteristics of the unit demonstrate quite worthy parameters that fit into the manufacturer’s promises, they nevertheless slightly disappoint: on most of the loads, the deviations in all voltages slightly exceed 1% of the nominal value – although confidently, with a good margin, they fit into the 2% tolerance . Recall that the manufacturer promised no more than 1% on lines 3 and 5 V, and also no more than 2% for voltage 12 V – plus 0.5% when changing the load on each of the lines. In these parameters, including voltage fluctuations of not more than 0.5% when the load changes, the unit fit.

However, an example of the already mentioned ASUS ROG Thor 1200W Platinum, which is related in design with ideal stability of all voltages, suggests that, most likely, we were just a little unlucky with the specimen.

12V bus, high frequency ripple

12V bus, high frequency ripple

12V bus, low frequency ripple

12V bus, low frequency ripple

5V bus, high frequency ripple

5V bus, high frequency ripple

5V bus, low frequency ripple

5V bus, low frequency ripple

With a voltage of 12 V at a low frequency, the peak peak-to-peak ripple is about 20 mV (with a permissible 120 mV), while at a high frequency the ripple is practically absent. With a voltage of 5 V, the amplitude of the ripple is minimal both at low and at high frequency.

⇡ #findings

The Seasonic PRIME TX-750 power supply has demonstrated very good parameters: decent voltage stability, minimal ripple and excellent efficiency. Also in the asset of the model is a very rich delivery set and a record duration of the warranty.

Of the shortcomings, one can note only blots in the operation of the cooling system: a noisy start of the fan and a slightly overestimated (although not causing the slightest acoustic discomfort) speed when working at low and medium loads. And of course, a price that is far from universal availability.

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