Corsair HX750W Power Supply Review

paulktreg - 2009-07-07 13:33:32 in Power Supplies
Category: Power Supplies
Reviewed by: paulktreg   
Reviewed on: August 2, 2009
Price: $164.99

Introduction:

The HX750W is Corsair's latest addition to its power supply line and joins the other modular units in the HX family. What are the advantages and disadvantages, if any, to a modular design? I have seen some modular power supply designs with a full set of modular cables, including the motherboard and ATX12V/EPS12V cables. All ATX based motherboards need a 20/24 motherboard connector and an auxiliary processor supply of some description, so making these modular makes little sense. A captive 20/24-pin motherboard connector and usually a 4+4-pin ATX12V/EPS12V connector is how most manufacturers design its modular units. One obvious advantage of the modular power supply is the option to use only the cables that are needed to supply power to the installed hardware. This in turn helps to keep the enclosure a little tidier, thus improving air flow and cooling. Cable management, a little time spent routing and fixing the cables, can improve cooling further and make things look much cleaner. Volt drop in the extra plug and socket that is introduced into the circuit is often cited as a disadvantage of the modular power supply. I have measured this volt drop on a fully loaded power supply and it is only in the order of a few tens of millivolts, so can it make a difference? Go out and buy two identical power supplies, measure the rail voltages and I guarantee they won't be same. Component tolerances will always lead to small rail voltage differences between two identical power supplies, so does losing a few tens of millivolts across a connector really matter? I'll let you answer that one. Think about it while you are reading this review from start to finish.

"Corsair Professional Series power supplies set a new standard by which all premium PSUs must be judged. Designed and engineered using cutting-edge technology, each Corsair Professional Series power supply is built to the highest quality standards, and delivers the features and performance that technology enthusiast's demand."

Corsair has been manufacturing memory for servers, high-end workstations and the gaming PC market since 1994. Its product range has grown over the years and alongside its extensive range of memory modules, the company now offers solid state and USB drives, computer cases and fans, water cooled memory blocks, and power supplies. The CX400 at 400 watts to the HX1000 at 1000 watts, with several in between, make up the current Corsair power supply range. I have tested three of them already for OCC, the HX520W, TX750W and the HX1000W, and they all performed very well. Let's see how well the HX750W can perform.

 

Closer Look:

The packaging on the Corsair HX750W follows what is a fairly standard design used for all its power supplies. This time around the theme is blue and black with the occasional splash of color. The top of the box shows a photograph of the modular connector panel along with the model number in large clear text, Nvidia SLI Ready logo and a 7 year warranty icon. The underside of the box shows the technical details, specification table, fan noise against loading graph, and an efficiency graph at 115VAC and 230VAC. The "Corsair Advantages" are listed in five different languages along with a photograph to illustrate each point. A photograph along the bottom shows the power supply with modular cables connected.

 

 

 

 

 

 

 

 

A short paragraph on one side panel, again in five different languages, explaining the advantages of the modular design and how the use of flat modular cables will help maximise airflow through the computer chassis.

 

 

Photographs of all the available connectors and quantities appear on the front panel, while the Corsair HX750W feature list is on the back panel, again in five different languages.

 

 

A black Velcro seal bag containing all the modular cables sits neatly down the side of the power supply's black foam envelope, on which the user manual lays. Lift off the foam lid and the power supply is contained in a black velvet draw string bag.

 

 

Below, you can see the cloth-enclosed power supply showing the captive 20/24-pin motherboard and EPS12V 4+4-pin cables and connectors held together with a black wire tie. You can also see the complete box contents, showing the modular cable bag, user manual, AC power cord, and a small plastic bag containing four mounting screws, cable ties and Corsair case badge. You will also see a small bag of silica gel to keep things moisture free.

 

 

Box design, packaging and contents are excellent and, if it in any way reflects on the contents, then the HX750W should perform very well.

 

Closer Look:

The Corsair HX750W is finished in the usual slightly textured matte black paint finish with the labels following the packaging's blue/black theme. The power supply, much like most modular units, has the 24-pin and 8-pin connectors terminate at the PCB inside the housing and are sleeved to protect the wiring, as well as provide better aesthetics.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Power supply back panel with hexagonal honeycombed grill, IEC mains input and mains on/off switch. The front panel of the power supply showing the modular cable sockets, blue for the four PCI-E cables and black for the peripheral, SATA and FDD supplies.

 

 

Blue and black Corsair HX750W label on either side.

 

 

Large 140mm black cooling fan with black grill bearing the Corsair logo at its center and the specification label on the underside.

 

 

Below, you'll find a photograph showing the captive motherboard 20/24-pin connector and EPS/ATX12V 4+4-pin connector. Both cables are fully braided all the way into the enclosure, which is nice to see. The modular cable set is made using low profile flat cables that, according to the supplied literature, "allows for superior airflow." However, unless a little cable management is utilized, they could also impede airflow more than the usual round cable profile. I don't like the use of all black cables, but this is probably due to the fact that I am constantly measuring voltages here and there and a little colour helps me recognize the rails. This won't prove to be a problem for most users, so I can't really fault Corsair. Instead of the usual wired hard disk drive power connectors, Corsair have opted to supply two peripheral to FDD adapter cables. Not a bad idea since the floppy disk drive is becoming an optional extra these days.

 

 

 The Corsair HX750W uses the 140mm GP D14BH-12(L-SSS) fan, rated at 12VDC 0.7A and manufactured by Yate Loon.

 

I expected to see the same board as used in the TX750W, but Corsair has used a completely different design. I couldn't find any indication of a manufacturer, but the board utilizes DC-to-DC converters for the 3V3 and 5V rails and a bit of extra capacitance on the primary, with two 330uF 420V electrolytics in parallel. The two DC-to-DC converter boards are the two upright boards in the bottom of the photograph above the yellow cable loom. Corsair's claimed feature of 105°C solid state capacitors is perhaps a little misleading. They are all rated at 105°C as stated, but the majority are standard Nippon Chemi-Con electrolytics and solid state capacitors are only used on the two small DC-to-DC converter boards.

 

The two main switching transformers can be seen towards the center of the board. The larger of the two, with the green top, takes care of the +12V rail and the adjacent smaller transformer is used for the +5VSB supply.

 

 

The overall build quality is excellent. I can't fault it so far, so let's move on.

 

Specifications:

Ratings Table:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corsair HX750W Specifications (Model: CMPSU-750HX)
AC Input
100-240VAC     10A     50-60Hz
DC Output
+3V3
+5V
+12V
-12V
+5VSB
Maximum Load
25A
25A
62A
0.8A
3A
Maximum Combined Wattage
150W
744W
9.6W
15W
Total Power: 750W

 

System Protection:

 

Corsair HX750W
Over Current Protection
DC Rail
Trigger Point
+3V3
44A
+5V
44A
+12V
90A
Over Voltage Protection
DC Rail
Trigger Point
+3V3
4.5V Max
+5V
7.0V Max
+12V
15.6V Max
Over Power Protection
Fold back at approximately 110%~150% of rated maximum load
Short Circuit Protection
All outputs to ground

 

Safety & Agency Approvals:

 

 

Power Supply Weight:

 

Power Supply Weight
Manufacturer/Model
Weight
Corsair HX750W
2.5kg
5.5lbs

 

Power Supply Connectors:

 

Corsair HX750W Connectors
20+4 Pin Motherboard
Captive
1
ATX12V 4+4 Pin or EPS12V 8 Pin
Captive
1
Peripheral 4 Pin
Modular
8
SATA Power
Modular
12
FDD
Adapter
2
PCI-E 6+2 Pin
Modular
4

 

Power Supply Cable Lengths:

 

Corsair HX750W Connector Cable Lengths
Captive
PSU > 24” > 20+4 Pin Motherboard
1
Captive
PSU > 24” > 4+4 Pin ATX12V/EPS 12V
1
Modular
PSU > 18” > Peripheral > 4” > Peripheral > 4” > Peripheral > 4” > Peripheral
2
Modular
PSU > 18” > SATA > 4” > SATA > 4” > SATA > 4” > SATA
3
Modular
PSU > 24” > PCI-E 6+2 Pin
4
Adapter
Peripheral > 4” > FDD
2

 

Corsair Advantages:

Exactly as printed in the user manual.

 

Corsair Core Features:

Exactly as printed in the user manual.

 

Testing:

For more information on how we test our power supplies, please browse our testing methodology.

Electrical Safety:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Electrical Safety Test Class 1
Manufacturer/Model
Pass/Fail
Corsair HX750W
Pass

 

Short Circuit Protection:

I short circuited the 3V3, 5V0 and the 12V rail in turn. The power supply did shut down, and once the short was removed and the unit switched off for at least one second, resumed normal operation. Although listed here at the beginning of the testing section, I tend to leave this test until the very end, in case it doesn't quite go to plan.

 

DC Output Voltage Load Regulation:

 

Mains Input Voltage 110VAC

 

 

Corsair HX750W
DC Output Voltage Load Regulation
AC Supply = 110V / DC Load = 0W
PSU DC Rail
Measured Voltage(V)
3V3
3.35
5V0
5.11
+12V
12.19
-12V
-12.18
5VSB
5.11

 

Corsair HX750W
DC Output Voltage Load Regulation
110VAC - Total Load at 174W which is 23% of Rated Maximum Output Power
PSU
DC Rail
Measured
Voltage(V)
Measured
Current (A)
Load Power
(W)
ATX12V V Limits
(V)
Pass/Fail
+3V3
3.35
3.12
10.45
3.135 – 3.465
Pass
+5V
5.11
4.74
24.22
4.75 – 5.25
Pass
+12V
12.18
10.29
125.33
11.4 – 12.6
Pass
-12V
11.61
0.33
3.83
10.8 – 13.2
Pass
+5VSB
4.97
2.03
10.09
4.75 – 5.25
Pass
Total Power Supply Loading
174W
 

 

Corsair HX750W
DC Output Voltage Load Regulation
110VAC - Total Load at 415W which is 55% of Rated Maximum Output Power
PSU
DC Rail
Measured
Voltage(V)
Measured
Current (A)
Load Power
(W)
ATX12V V Limits
(V)
Pass/Fail
+3V3
3.34
7.90
26.39
3.135 – 3.465
Pass
+5V
5.10
9.33
47.58
4.75 – 5.25
Pass
+12V
12.16
26.87
326.74
11.4 – 12.6
Pass
-12V
11.67
0.33
3.85
10.8 – 13.2
Pass
+5VSB
4.97
2.03
10.09
4.75 – 5.25
Pass
Total Power Supply Loading
415W
 

 

Corsair HX750W
DC Output Voltage Load Regulation
110VAC - Total Load at 728W which is 97% of Rated Maximum Output Power
PSU
DC Rail
Measured
Voltage(V)
Measured
Current (A)
Load Power
(W)
ATX12V V Limits
(V)
Pass/Fail
+3V3
3.33
11.97
39.86
3.135 – 3.465
Pass
+5V
5.10
13.82
70.48
4.75 – 5.25
Pass
+12V
12.13
49.78
603.83
11.4 – 12.6
Pass
-12V
11.85
0.34
4.03
10.8 – 13.2
Pass
+5VSB
4.96
2.03
10.07
4.75 – 5.25
Pass
Total Power Supply Loading
728W
 

 

Mains Input Voltage 230VAC

 

 

Corsair HX750W
DC Output Voltage Load Regulation
AC Supply = 230V / DC Load = 0W
PSU DC Rail
Measured Voltage(V)
3V3
3.35
5V0
5.11
+12V
12.19
-12V
-12.31
5VSB
5.11

 

Corsair HX750W
DC Output Voltage Load Regulation
230VAC - Total Load at 174W which is 23% of Rated Maximum Output Power
PSU
DC Rail
Measured
Voltage(V)
Measured
Current (A)
Load Power
(W)
ATX12V V Limits
(V)
Pass/Fail
+3V3
3.35
3.12
10.45
3.135 – 3.465
Pass
+5V
5.11
4.74
24.22
4.75 – 5.25
Pass
+12V
12.18
10.29
125.33
11.4 – 12.6
Pass
-12V
11.61
0.33
3.83
10.8 – 13.2
Pass
+5VSB
4.97
2.03
10.09
4.75 – 5.25
Pass
Total Power Supply Loading
174W
 

 

Corsair HX750W
DC Output Voltage Load Regulation
230VAC - Total Load at 416W which is 55% of Rated Maximum Output Power
PSU
DC Rail
Measured
Voltage(V)
Measured
Current (A)
Load Power
(W)
ATX12V V Limits
(V)
Pass/Fail
+3V3
3.34
7.92
26.45
3.135 – 3.465
Pass
+5V
5.10
9.39
47.89
4.75 – 5.25
Pass
+12V
12.17
26.92
327.62
11.4 – 12.6
Pass
-12V
11.74
0.34
3.99
10.8 – 13.2
Pass
+5VSB
4.97
2.03
10.01
4.75 – 5.25
Pass
Total Power Supply Loading
416W
 

 

Corsair HX750W
DC Output Voltage Load Regulation
230VAC - Total Load at 729W which is 97% of Rated Maximum Output Power
PSU
DC Rail
Measured
Voltage(V)
Measured
Current (A)
Load Power
(W)
ATX12V V Limits
(V)
Pass/Fail
+3V3
3.33
11.73
39.06
3.135 – 3.465
Pass
+5V
5.10
13.54
69.05
4.75 – 5.25
Pass
+12V
12.13
50.05
607.10
11.4 – 12.6
Pass
-12V
11.85
0.34
4.03
10.8 – 13.2
Pass
+5VSB
4.95
2.03
10.05
4.75 – 5.25
Pass
Total Power Supply Loading
729W
 

 

Excellent DC voltage load regulation. The Corsair HX750W hardly bats an eye as the load approaches maximum. No problems here, so let's move on.

 

Testing :

Efficiency and Power Factor:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corsair HX750W
Output & Efficiency @ 110VAC
DC Load (W)
AC Load (W)
PF
Efficiency (%)
Pass/Fail
0
9
0.69
N/A
N/A
174
197
0.99
88
Pass
415
468
1.00
89
Pass
728
860
1.00
85
Pass

 

Corsair HX750W
Output & Efficiency @ 230VAC
DC Load (W)
AC Load (W)
PF
Efficiency (%)
Pass/Fail
0
14
0.32
N/A
N/A
173
194
0.92
89
Pass
416
462
0.97
90
Pass
729
851
0.98
86
Pass

 

Some impressive figures from the Corsair HX750W, which easily meet the requirements of the ATX12V V2.2 specification. The Corsair HX750W also meets 80 Plus Silver, but more on that in the conclusion.

 

AC Ripple On DC Outputs:

 

I have consistently found the AC ripple levels on the DC rails to be more or less equal with a 110VAC or 230VAC mains supply. The results given below are for 230VAC only, but I will continue to check the levels at 110VAC during testing and publish them below if they differ in any way.

 

AC Ripple On 3V3 Rail at 230VAC

Oscilloscope settings: Amplitude = 5mv/div, Timebase = 10uS/div

 

AC Ripple On 5V0 Rail at 230VAC

Oscilloscope settings: Amplitude = 5mv/div, Timebase = 10uS/div

 

AC Ripple On 12V1 Rail at 230VAC

Oscilloscope settings: Amplitude = 5mv/div, Timebase = 10uS/div

 

Corsair HX750W
AC Ripple/Noise
DC Rail
+3V3
+5V0
+12V
-12V0
+5VSB
Ripple (mV p-p)
25
25
35
40
30
Pass/Fail
Pass
Pass
Pass
Pass
Pass

 

Excellent set of ripple/noise figures for a power supply delivering nearly 750W. I was especially impressed with the level on the +12V rail, which is excellent considering it was delivering over 600W.

 

Testing (Continued):

Temperature, Noise Levels and Fan Speeds:

 

I am not going to give a pass or fail in this section, as the ATX12V V2.2 does not really have any references on which to base a decision.

Temperatures are purely for information only, as there are too many variables involved when installed in a case, which, by the way, it wasn't. Ambient temperature, processor cooling efficiency and case cooling fans all play their part on the temperature of the air entering the power supply, and consequently the temperature of the air leaving it. No valid conclusions can be made from this test.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corsair HX750W
Temperature & Fan Speeds @ 230VAC
DC Loading(W)
Temp In (°C)
Temp Out (°C)
Δ Temp (°C)
Fan Speed (RPM)
0
N/A
N/A
N/A
0
173
22.5
26.5
4.0
985
416
22.3
30.3
8.0
991
729
21.3
40.7
19.4
1163

 

 

Once again I should point out that the power supply wasn't installed in a case. These temperatures are simply input and output air temperatures measured while bench testing the power supply and are given for reference only. Interestingly, the cooling fan did not start up when powered from 230VAC with no DC load, yet gave a fan speed of 955 rpm, again with no DC load, when powered from 110VAC. Please don't read too much into this, as it isn't going to cause any problems and is probably just a quirk in the temperature sensor/fan drive circuitry. When compared with the performance of the Corsair TX750W power supply, the temperatures are marginally less, but with substantially lower fan speeds, explained, no doubt, by the excellent efficiency of the Corsair HX750W. I have included the noise/loading graph from the box for your information. During testing, the only fans I could hear were the two attached to my test load! According to the graph and figures obtained during testing, you should expect a constant fan speed of approximately 1000 rpm up to about 525W. I found the Corsair HX750W fan to be very quiet throughout testing and fan noise should not be a problem.

 

Conclusion:

Environmental Factors:

The packaging of the Corsair HX750W does nothing to help the environment. The box and user manual could easily be manufactured from recycled materials, but alas, no mention on the box or packaging that this is the case. In addition, the use of foam as a power supply protector and the cloth power supply bag are really unnecessary; there must be an alternative? What does give the HX750W the edge over its competitors in this category is the best efficiency I have ever seen in a power supply tested for OCC, which will, over time, probably outweigh any cost incurred for the packaging, but does this excuse Corsair from trying harder in the environmental stakes.

 

Price Per the Watt:

Power Supply Corsair HX750W at $164.99 = $0.22/Watt (July 2009)

 

The Corsair HX750W is, without doubt, one of the best power supplies I have tested for OCC, although the testing phase wasn't without problems. The Corsair HX750W is certified to 80 Plus Gold according to the 80 Plus website and the literature that was supplied with the review unit, but it didn't quite hit the mark during testing. Corsair was contacted by OCC and in a promptly answered email we were informed the Corsair HX750W has been adjusted down to 80 Plus Silver, which is reflected on the Corsair website (but as of 07/28/09 not on the 80 Plus website). The Corsair HX750W was designed to comply with the 80 Plus Silver specification, but the unit submitted for testing qualified for 80 Plus Gold certification. The margin however was not large enough to ensure that every HX750W power supply produced would meet the 80 Plus Gold standard and consequently Corsair felt it could not make a marketing claim based on results that were marginal. As such, Corsair has chosen to market the HX750W as 80 Plus Silver, not Gold.

The Corsair HX750W is an 80 Plus Silver certified power supply and the figures obtained during testing confirmed this with the efficiency peaking at a massive 90% on 230VAC. Combine the excellent efficiency with top notch DC voltage load regulation and low ripple/noise on all the rails, and the Corsair HX750W is up there with the best. The box lid carries the Nvidia SLI Ready logo, but I wasn't able to confirm this on the Nvidia SLI website, so perhaps it will appear in the next update. The Corsair HX750W has four 6+2-pin PCI-E connectors, making it the ideal power supply for any high end SLI or Crossfire configuration, especially when you consider it delivered 50A on the 12V rail with very low noise.

This is a great power supply that I would not hesitate to recommend to anybody looking for a power supply in this range. You will get better efficiency from the Corsair HX750W across its full output range than most power supplies can manage at peak, so why not fit one anyway and wait for the word overkill to rear its ugly head. Imagine the TX750W with marginally better performance and modular cables and that about sums up the HX750W. I have no hesitation in awarding the Corsair CMPSU-750HX an Editors' Choice award.

 

Pros:

 

Cons: