Corsair GS700 Bronze Power Supply Review

[nextpage title=”Introduction”]

The Corsair GS power supply series is comprised of 500 W, 600 W, 700 W, and 800 W models, with either the standard 80 Plus certification or with the 80 Plus Bronze certification, except for the 500 W model, which is available only with the standard 80 Plus certification. Today we are reviewing the 700 W model with the 80 Plus Bronze certification. Let’s see if it is a good product.

By the way, we think it is very confusing to have two different power supplies with the same name. We think Corsair should have used a different name for the models with the 80 Plus Bronze certification.

The Corsair GS700 Bronze is manufactured by CWT.

Figure 1: Corsair GS700 Bronze power supply

Figure 2: Corsair GS700 Bronze power supply

The Corsair GS700 Bronze is 6.3” (160 mm) deep, using a 140 mm ball-bearing fan on its bottom (Hong Hua HA1425H12B-Z). The fan glows either in red, blue or white, and you can choose the color by pressing a button located on the power supply’s rear panel.The power supply only turns on its fan when load is above 25 percent. This way, the power supply produces no noise at light loads.

Figure 3: Fan

The reviewed power supply doesn’t have a modular cabling system. All cables are protected with nylon sleeves, which come from inside the unit. This power supply comes with the following cables:

• Main motherboard cable with a 20/24-pin connector, 22.8” (58 cm) long
• One cable with two ATX12V connectors that together form an EPS12V connector: 26” (66 cm) long
• Two cables, each with one six/eight-pin connector for video cards, 22” (56 cm) long
• Two cables, each with four SATA power connectors, 17.7” (45 cm) to the first connector, 3.9” (10 cm) between connectors
• Two cables, each with three standard peripheral power connectors and one floppy disk drive power connector, 17.7” (45 cm) to the first connector, 3.9” (10 cm) between connectors

All wires are 18 AWG, which is the minimum recommended gauge, except the main motherboard cable, which uses thicker 16 AWG wires. The number of connectors is good for a 700 W power supply.

Figure 4: Cables

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

[nextpage title=”A Look Inside the Corsair GS700 Bronze”]

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.

Figure 5: Top view

Figure 6: Front quarter view

Figure 7: Rear quarter view

Figure 8: The 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.

In the transient filtering stage, this power supply is flawless, with two Y capacitors and one X capacitor more than the minimum required.

Figure 9: Transient filtering stage (part 1)

Figure 10: Transient filtering stage (part 2)

On the next page, we will have a more detailed discussion about the components used in the Corsair GS700 Bronze.[nextpage title=”Primary Analysis”]

On this page, we will take an in-depth look at the primary stage of the Corsair GS700 Bronze. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.

This power supply uses one GBU1506 rectifying bridge attached to an individual heatsink. This bridge supports up to 15 A at 100° C. So, in theory, you would be able to pull up to 1,725 W from a 115 V power grid. Assuming 80% efficiency, this bridge would allow this unit to deliver up to 1,380 W without burning itself out. Of course, we are only talking about these particular components. The real limit will depend on all the components combined in this power supply.

Figure 11: Rectifying bridge

The active PFC circuit uses two SiHG20N50C MO
SFETs, each supporting up to 20 A at 25° C or 11 A at 100° C in continuous mode (see the difference temperature makes) or 80 A at 25° C in pulse mode. These transistors present a maximum 270 mΩ 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.

Figure 12: Active PFC transistors

The output of the active PFC circuit is filtered by a 390 µF x 420 V Japanese electrolytic capacitor, from Chemi-Con, labeled at 105° C.

Figure 13: Capacitor

In the switching section, two TK13A50D MOSFETs are employed using the traditional two-transistor forward configuration. Each transistor supports up to 13 A at 25° C in continuous mode or up to 52 A at 25° C in pulse mode, with a maximum RDS(on) of 400 mΩ. Unfortunately, the manufacturer doesn’t publish the current limits at 100° C.

Figure 15: Active PFC/PWM controller

Let’s now take a look at the secondary of this power supply.[nextpage title=”Secondary Analysis”]

The Corsair GS700 Bronze uses a synchronous design, meaning that the rectifiers were replaced with MOSFETs. Also, this power supply uses a DC-DC design, meaning that it is basically a +12 V power supply, with the +5 V and +3.3 V outputs being generated through two smaller switching power supplies connected to the +12 V rail. Both designs are used to increase efficiency.

The +12 V output uses five CEB6056 MOSFETS, each supporting up to 100 A at 25° C in continuous mode or up to 360 A at 25° C in pulse mode, with a maximum RDS(on) of 6.2 mΩ. These transistors are located on a small daughterboard.

Figure 16: The +12 V transistors

The DC-DC converters are located on a separate printed circuit board. Both are managed by an APW7159 PWM controller, with each output using three AP72T03GH MOSFETs, each supporting up to 63 A at 25° C or 44 A at 100° C in continuous mode or up to 190 A at 25° C in pulse mode, with a maximum RDS(on) of 9 mΩ.

Figure 17: The DC-DC converters

Figure 18: The DC-DC converters

The outputs of this power supply are monitored by a WT7502 integrated circuit, which only supports over voltage (OVP) and under voltage (UVP) protections.

Figure 19: Monitoring circuit

The electrolytic capacitors used in the secondary are from Samxon and labeled at 105° C, as usual. See Figure 20.

Figure 20: Capacitors

[nextpage title=”Power Distribution”]

In Figure 21, you can see the power supply label containing all the power specs.

Figure 21: Power supply label

As you can see, this power supply 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 find out.

[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, 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, both inputs were connected to the power supply’s single +12 V rail. (The power supply’s EPS12V connector was installed on the +12VB input of the load tester.)

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12VA	4.5 A (54 W)	9.5 A (114 W)	14.5 A (174 W)	19 A (228 W)	25 A (300 W)
+12VB	4.5 A (54 W)	9.5 A (114 W)	14.5 A (174 W)	19 A (228 W)	25 A (300 W)
+5 V	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	136.5 W	276.0 W	414.4 W	540.4 W	700.4 W
% Max Lo ad	19.5%	39.4%	59.2%	77.2%	100.1%
Room Temp.	44.9° C	44.8° C	46.1° C	49.2° C	48.2° C
PSU Temp.	51.3° C	51.5° C	51.4° C	51.6° C	52.0° C
Voltage Regulation	Pass	Pass	Pass	Pass	Pass
Ripple and Noise	Pass	Pass	Pass	Pass	Pass
AC Power	160.2 W	317.4 W	481.3 W	640.0 W	859.0 W
Efficiency	85.2%	87.0%	86.1%	84.4%	81.5%
AC Voltage	113.9 V	112.9 V	111.5 V	109.7 V	107.1 V
Power Factor	0.973	0.989	0.994	0.996	0.997
Final Result	Pass	Pass	Pass	Pass	Pass

The 80 Plus Bronze certification promises a minimum efficiency of 85% at typical load (i.e., 50% load) and a minimum efficiency of 82% at light (i.e., 20% load) and full loads. The Corsair GS700 Bronze presented efficiency between 81.5% and 87.0% during our tests. At the full load test, efficiency was a tad below 82%, which can be explained by the AC voltage at our lab that dropped to 107.1 V, and power supplies present lower efficiency at lower AC voltages. Also, while we test power supplies at temperatures between 45° C and 50° C, the 80 Plus tests are conducted at 23° C, and efficiency drops as temperature increases. Therefore, we can claim the Corsair GS700 Bronze passed our efficiency tests.

All voltages were closer to their nominal values during all tests (3% voltage regulation), except the -12 V output during test one, at -11.59 V, but still inside the allowed range. 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.

Let’s discuss the ripple and noise levels on the next page.

[nextpage title=”Ripple and Noise Tests”]

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 Corsair GS700 Bronze provided extremely low ripple and noise levels, making it a “flawless” unit here as well.

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12VA	6.8 mV	8.8 mV	11.4 mV	15.0 mV	22.4 mV
+12VB	9.0 mV	13.0 mV	17.4 mV	21.6 mV	31.2 mV
+5 V	7.0 mV	7.2 mV	7.0 mV	7.6 mV	8.2 mV
+3.3 V	9.4 mV	11.8 mV	12.4 mV	14.0 mV	17.0 mV
+5VSB	10.0 mV	11.6 mV	13.8 mV	16.8 mV	21.6 mV
-12 V	25.4 mV	38.2 mV	53.0 mV	71.2 mV	87.2 mV

Below you can see the waveforms of the outputs during test five.

Figure 22: +12VA input from load tester during test five at 700.4 W (22.4 mV)

Figure 23: +12VB input from load tester during test five at 700.4 W (31.2 mV)

Figure 24: +5V rail during test five at 700.4 W (8.2 mV)

Figure 25: +3.3 V rail during test five at 700.4 W (17.0 mV)

[nextpage title=”Overload Tests”]

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, as it shut down when we tried to pull more than what is listed in the table below. Noise and ripple levels were still low and voltages were still within 3% of their nominal values.

Input	Overload Test
+12VA	28 A (336 W)
+12VB	28 A (336 W)
+5 V	15 A (75 W)
+3.3 V	10 A (33 W)
+5VSB	3 A (15 W)
-12 V	0.5 A (6 W)
Total	787.8 W
% Max Load	112.5%
Room Temp.	45.4° C
PSU Temp.	49.7° C
AC Power	995.0 W
Efficiency	79.2%
AC Voltage	104.7 V
Power Factor	0.997

[nextpage title=”Main Specifications”]

The main specifications for the Corsair GS700 Bronze power supply include:

• Standards: ATX12V 2.3 and EPS12V 2.91
• Nominal labeled power: 700 W at 40° C
• Measured maximum power: 787.8 W at 45.4° C
• Labeled efficiency: Up to 85%, 80 Plus Bronze certification
• Measured efficiency: Between 81.5% and 87.0% 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: Two six/eight-pin connectors on separate cables
• SATA Power Connectors: Eight on two cables
• Peripheral Power Connectors: Six 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? This unit has over voltage (OVP), under voltage (UVP), over power (OPP), and short-circuit (SCP) protections.
• Warranty: Three years
• More Information: https://www.corsair.com
• Average Price in the U.S.*: USD 120.00

* Researched at Newegg.com on the day we published this review.[nextpage title=”Conclusions”]

The new Corsair GS700 Bronze is a flawless power supply, with superb voltage regulation, extremely low noise and ripple levels, and terrific efficiency for the mainstream user (between 81.5% and 87.0% during our
tests). The cable configuration is good for a 700 W unit.

The highlight of this power supply is its fan, with a button allowing you to change the color of its LEDs, and the fact that the fan stays off at light loads. This way, you have the quietest operation possible.

The price tag of the reviewed power supply is on the high side. Just to put things into perspective, let’s make a quick comparison of the Corsair GS700 Bronze to some of the power supplies in the same power range that we reviewed recently.

The FSP Raider 650 W presents higher efficiency and costs less (USD 100); however, the Corsair GS700 Bronze has better voltage regulation, lower noise and ripple levels, and a higher labeled wattage.

The XFX PRO 650 W XXX Edition also costs less (USD 100) and comes with a modular cabling system, but the model from Corsair achieved higher efficiency, has better voltage regulation, and comes with a higher labeled wattage.

The InWin GreenMe 650 W costs far less than the Corsair GS700 (USD 85), but the model from Corsair presents lower noise and ripple levels and has a higher labeled wattage.

The Ximatek Tauro 700 W also costs less, but the Corsair GS700 Bronze presents higher efficiency and lower noise and ripple levels.

The only real competition we see for the Corsair GS700 Bronze is the Rosewill FORTRESS-650, as they cost exactly the same, but the Rosewill model comes with the 80 Plus Gold certification. The GS700 Bronze, however, is labeled with a higher wattage and presents lower ripple and noise levels.

In summary, the Corsair GS700 Bronze is targeted to the savvy user who wants to buy an affordable, “flawless” power supply with the 80 Plus Bronze certification.