Corsair TX750 V2 Power Supply Review

[nextpage title=”Introduction”]

Let’s take a look at the revamped Corsair TX750 power supply, dubbed TX750 V2, now featuring a DC-DC design and 80 Plus Bronze certification.

It is important to understand that while the old TX750 was manufactured by CWT, being a relabeled 750VH unit from this manufacturer, the new Corsair TX750 V2 is manufactured by Seasonic, being internally identical to the XFX PRO 750 W unit.

The only differences between the Corsair TX750 V2 and the XFX PRO 750 W are the fan (140 mm on the Corsair model and 135 mm on the XFX model), the configuration of the video card connectors (four six/eight-pin on the Corsair model and two six-pin and two six/eight-pin on the XFX model), and the configuration of the peripheral power cables (two cables with four standard peripheral power connectors and one floppy disk drive power connector each on the Corsair model and one cable with four standard peripheral power connectors and one cable with three peripheral power connectors and one floppy disk drive power connector on the XFX model).

Figure 1: Corsair TX750 V2 power supply

Figure 2: Corsair TX750 V2 power supply

The TX750 V2 is 6.3” (160 mm) deep, with a 140 mm dual ball bearing fan (Yate Loon D14BH-12, 2,800 rpm, 140 cfm, 48.5 dB) on its bottom part.

The new Corsair TX750 V2 doesn’t have a modular cabling system. All cables are protected with nylon sleeves. The power supply comes with the following cables:

• Main motherboard cable with a 20/24-pin connector, 23.2” (59 cm) long
• One cable with two ATX12V connectors that together form an EPS12V connector, 23.6” (60 cm) long
• Four cables, each with one six/eight-pin connector for video cards, 23.6” (60 cm) long
• Two cables, each with four SATA power connectors, 16.1” (41 cm) to the first connector, 5.9” (15 cm) between connectors
• Two cables, each with four standard peripheral power connectors and one floppy disk drive power connector, 15.7” (40 cm) to the first connector, 5.5” (14 cm) between connectors

All wires are 18 AWG, which is the minimum recommended gauge.

The cable configuration is adequate for a 750 W unit.

Figure 3: Cables

Let’s now take an in-depth look inside this power supply.

[nextpage title=”A Look Inside The Corsair TX750 V2″]

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 already explained, the Corsair TX750 V2 is internally identical to the XFX PRO 750 W.

Figure 4: Top view

Figure 5: Front quarter view

Figure 6: Rear quarter view

Figure 7: Printed circuit board

[nextpage title=”Transient Filtering Stage”]

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. 

The transient filtering stage of the Corsair TX750 V2 is impeccable, coming with all required components plus one extra X capacitor, one extra ferrite coil, and four extra Y capacitors.

Figure 8: Transient filtering stage (part 1)

Figure 9: Transient filtering stage (part 2)

In the next page we will have a more detailed discussion about the components used in the Corsair TX750 V2.

[nextpage title=”Primary Analysis”]

On this page we will take an in-depth look at the primary stage of the Corsair TX750 V2 For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU806 rectifying bridges connected in parallel, both attached to an individual heatsink. Each bridge supports up to 8 A at 100° C so, in theory, you would be able to pull up to 1,840 W from a 115 V power grid. Assuming 80% efficiency, the bridges would allow this unit to deliver up to 1,472 W without burning themselves out. Of course, we are only talking about these components, and the real limit will depend on all the other components in this power supply.

Figure 10: Rectifying bridges

The active PFC circuit uses two SPP24N60C3 MOSFETs, which are capable of delivering up to 24.3 A at 25° C or up to 15.4 A at 100° C (note the difference temperature makes) in continuous mode, or up to 72.9 A in pulse mode at 25° C, each. These transistors present a 160 mΩ resistance when turned on, a characteristic called RDS(on). The lower this number the better, meaning that the transistors will waste less power and the power supply will achieve a higher efficiency. It is interesting to note how, in order to improve thermal dissipation, the manufacturer added a metallic plate between these transistors and the aluminum heatsink (see Figure 11).

Figure 11: Active PFC transistors

This power supply uses two electrolytic capacitors to filter the output from the active PFC circuit. The use of more than one capacitor here has absolute nothing to do with the “quality” of the power supply, as laypersons may assume (including people without the proper background in electronics doing power supply reviews around the web). Instead of using one big capacitor, manufacturers may choose to use two or more smaller components that will give the same total capacitance, in order to better accommodate space on the printed circuit board. Also, the use of two capacitors in parallel divides the current that flows through each one of them, reducing the amount of heat generated. The Corsair TX750 V2 uses one 220 µF x 400 V and one 330 x 400 V capacitors connected in parallel; this is the equivalent of one 550 µF x 400 V capacitor. These capacitors are Japanese, from Rubycon, and labeled at 105° C.

In the switching section, two SPP20N60C3 MOSFET transistors are used, installed in the two-transistor forward configuration. Each one is capable of delivering up to 20.7 A at 25° C or up to 13.1 A at 100° C (note the difference temperature makes) in continuous mode, or up to 62.1 A in pulse mode at 25° C, each. These transistors present a 190 mΩ RDS(on).

Figure 12: One of the switching transistors

The primary is controlled by a CM6802 active PFC/PWM combo controller.

Figure 13: Active PFC/PWM combo controller

Now let’s take a look at the secondary of this power supply.

[nextpage title=”Secondary Analysis”]

This power supply uses a DC-DC project in its secondary, meaning that this unit is basically a +12 V power supply. The +5 V and +3.3 V outputs are produced by two smaller switching power supplies connected to the +12 V rail. This design is used to increase efficiency.

The +12 V output make use of five SBR30A50CT Schottky rectifiers, each one capable of handling up to 30 A (15 A per internal diode at 110° C, 0.55 V maximum voltage drop). From the ten available diodes (two per rectifier pack), four are used in the direct rectification and six are used in the “freewheeling” part of the rectification. This would give us a maximum theoretical current of 86 A or 1,029 W for the +12 V output, but keep in mind that the +5 V and +3.3 V outputs are generated from the +12 V output.

Figure 14: +12 V rectifiers

As explained, the +5 V and +3.3 V outputs are generated using two DC-DC converters (i.e., two switching power supplies). Usually power supplies using this design have these two converters installed on separate daughterboards, but in the Corsair TX750 V2 they are available on the same board, shown in Figures 15 and 16. The two converters are managed by the same PWM chip (APW7159), and use seven APM2556N MOSFET transistors, each one being able to handle up to 160 A at 25° C or 90 A at 100° C with an RDS(on) of only 4.5 mΩ.

Figure 15: The +5 V and +3.3 V DC-DC converter

Figure 16: The +5 V and +3.3 V DC-DC converter

The secondary is monitored by a PS223 integrated circuit, which supports over voltage protection (OVP), under voltage protection (UVP), over current protection (OCP), and over temperature protection (OTP). This integrated circuit has four OCP channels (+3.3 V, +5V and two +12 V), but the manufacturer decided to use only one of the +12 V channels, making this a single-rail power supply.

Figure 17: Monitoring circuit

All electrolytic capacitors used in the secondary are also Japanese, from Chemi-Con, and labeled at 105° C.

[nextpage title=”Power Distribution”]

In Figure 18, you can see the power supply label containing all the power specs.

Figure 18: Power supply label

Since this unit has a single +12 V rail, there is not much to talk about here.

Let’s now see if this power supply can really deliver 750 W.

[nextpage title=”Load Tests”]

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, t
rying 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 our tests, the +12VA and +12VB input were connected to the power supply single +12 V rail (the EPS12V connector was installed on the +12VB input of our load tester).

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12VA	5 A (60 W)	11 A (132 W)	16 A (192 W)	22 A (264 W)	27 A (324 W)
+12VB	5 A (60 W)	10 A (120 W)	16 A (192 W)	21 A (252 W)	27 A (324 W)
+5V	2 A (10 W)	4 A (20 W)	6 A (30 W)	8 A (40 W)	10 A (50 W)
+3.3 V	2 A (6.6 W)	4 A (13.2 W)	6 A (19.8 W)	8 A (26.4 W)	10 A (33 W)
+5VSB	1 A (5 W)	1.5 A (7.5 W)	2 A (10 W)	2.5 A (12.5 W)	3 A (15 W)
-12 V	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)
Total	147.6 W	298.2 W	412.4 W	598.4 W	748.4 W
% Max Load	19.7%	39.8%	55.0%	79.8%	99.8%
Room Temp.	46.3° C	45.6° C	46.0° C	49.8° C	45.1° C
PSU Temp.	38.9° C	40.8° C	41.8° C	44.2° C	45.6° C
Voltage Regulation	Pass	Pass	Pass	Pass	Pass
Ripple and Noise	Pass	Pass	Pass	Pass	Pass
AC Power	177.4 W	348.2 W	483.4 W	710.0 W	905.0 W
Efficiency	83.2%	85.6%	85.3%	84.3%	82.7%
AC Voltage	117.6 V	116.5 V	114.9 V	112.5 V	109.4 V
Power Factor	0.985	0.989	0.993	0.996	0.998
Final Result	Pass	Pass	Pass	Pass	Pass

The Corsair TX750 V2 passed our test with flying colors, being able to deliver its labeled wattage at high temperatures.

Efficiency was very good, between 82.7% and 85.6%, correctly matching the 80 Plus Bronze certification, which requires a minimum 82% efficiency at light (20%) and full loads, and 85% minimum at typical (50%) load.

Voltage regulation was superb, with all voltages within 3% of their nominal values, including the -12 V output. The ATX12V specification allows voltages to be up to 5% from their nominal values (10% for the -12 V output). Therefore this power supply presents voltages closer to their nominal values than necessary all the time.

Noise and ripple levels were always extremely low. Below you can see the results for the power supply outputs during test number five. The maximum allowed is 120 mV for the +12 V and -12 V outputs, and 50 mV for the +5 V, +3.3 V, and +5VSB outputs. All values are peak-to-peak figures.

Figure 19: +12VA input from load tester during test five at 748.4 W (24.2 mV)

Figure 20: +12VB input from load tester during test five at 748.4 W (28.2 mV)

Figure 21: +5V rail during test five at 748.4 W (9.2 mV)

Figure 22: +3.3 V rail during test five at 748.4 W (8 mV)

Let’s see if we can pull even more from the Corsair TX750 V2.

[nextpage title=”Overload Tests”]

Below you can see the maximum we could pull from this power supply. We couldn’t pull more than that because the power supply shut down, showing that its protections were working just fine. Under this scenario, voltages were still with 3% of their nominal values and noise/ripple were still very low.

Input	Overload Test
+12VA	32 A (384 W)
+12VB	32 A (384 W)
+5V	14 A (70 W)
+3.3 V	14 A (46.2 W)
+5VSB	3 A (15 W)
-12 V	0.5 A (6 W)
Total	900 W
% Max Load	120.0%
Room Temp.	42.4° C
PSU Temp.	41.5° C
AC Power	1,123 W
Efficiency	80.1%
AC Voltage	107.6 V
Power Factor	0.998

[nextpage title=”Main Specifications”]

The specs of the Corsair TX750 V2 include:

• Standards: ATX12V 2.3 and EPS12V 2.91
• Nominal labeled power: 750 W
• Measured maximum power: 900 W at 42.4° C ambient
• Labeled efficiency: Up to 85%, 80 Plus Bronze certification
• Measured efficiency: Between 82.7% and 85.6%, at 115 V (nominal, see complete results for actual voltage)
• Active PFC: Yes
• Modular Cabling System: No
• Motherboard Power Connectors: One 20/24-pin connector and two ATX12V connectors that together form an EPS12V connector
• Video Card Power Connectors: Four six/eight-pin connectors on separate cables
• SATA Power Connectors: Eight on two cables
• Peripheral Power Connectors: Eight on two cables
• Floppy Disk Drive Power Connectors: Two on two cables
• Protections (as listed by the manufacturer): NA
• Are the above protections really available? Although not listed by the manufacturer, over voltage (OVP), under voltage (UVP), over current (OCP), over temperature (OTP), over power (OPP), and short-circuit (SCP) protections are available
• Warranty: Five years
• Real Manufacturer: Seasonic
• More Information: https://www.corsair.com
• Average Price in the US*: USD 120.00 (USD 100 after a mail-in rebate)

* Researched at Newegg.com on the day we published this review.

[nextpage title=”Conclusions”]

The Corsair TX750 V2 is a decent power supply, clearly targeted to users that want good 750 W unit at an affordable price. It passed our tests with flying colors, with good efficiency, outstanding voltage regulation, ultra-low noise and ripple levels, and good cable configuration.

Compared to the old TX750, the new version is a no-brainer, providing higher efficiency and far lower noise and ripple levels.

We discovered that this unit is internally identical to the XFX PRO 750 W, and both are sold for exactly the same price: USD 120 or USD 100 after a mail-in rebate, which is a terrific price for what these units offer.

There are minor differences between the two units, though. The Corsair TX750V2 comes with a slightly bigger fan (140 mm vs. 135 mm on the XFX model), all video card power connectors have six/eight pins (on the XFX model only two are six/eight-pin models, the other two are regular six-pin models), and one extra peripheral power connector and one extra floppy disk drive power connector.