Corsair TX550M & TX750M Power Supply Review

paulktreg - 2011-08-10 12:30:14 in Power Supplies
Category: Power Supplies
Reviewed by: paulktreg   
Reviewed on: February 21, 2012
Price: $99.99 & $129.99

Introduction:

For over fifteen years, Corsair has been building PC enthusiast-grade products and in that time, has earned a reputation for quality and performance. In the early years, their core business mainly focused on memory modules, but since then, they have built up a portfolio of products that include memory, solid state drives, enclosures, and power supplies.

This time around, OCC is taking a look at a couple of power supplies from Corsair’s recently introduced modular enthusiast power supply range: the TX550M and TX750M. The M series of power supplies feature a completely new design – it is not a modified version of the older TX and TX V2 power supplies. M stands for modular, although both units still have a captive cable set alongside a selection of modular cables. Let's have a closer look at two of the new M series power supplies and see if they can uphold the tradition.

Closer Look:

The packaging of the TX550M and TX750M power supplies pretty much follow the theme used throughout the rest of Corsair’s product range; the differences are obvious – model number and technical specifications – so there's little point in showing both boxes from all angles.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The top face of the box carries a photograph of the power supply fan grill along with the model number in yellow text indicating the TX series. The bottom face of the box carries all the technical information which includes connector types and quantities, a specification table, brief descriptions of some major features, and two graphs used to illustrate fan noise and efficiency. The front and rear faces provide more featured information, with the end panels clearly showing the model number.

 

 

 

Once again, Corsair packed their power supply in a box, in another box.

 

Lifting the lid, the power supply can be seen well protected in black foam and a black felt drawstring bag. The power supply’s captive cables, a plastic bag containing the modular cables, power cord, and a little bag with some cable ties, case badge, and power mounting screws neatly occupy the remaining space. The review samples came with two leaflets, safety information, and warranty guide, but no user manual. There was, however, an invitation with a webpage address to download a complete user guide, but at the time of writing this article, an obvious link was nowhere to be found.

 

 

 

Once again, the power supplies are very well packaged with a good set of accessories, although a user manual would be a welcome addition. Let's move on and have a closer look.

Closer Look:

The Corsair TX550M and TX750M are both finished with a slightly textured matt black paint.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The hexagonal-holed exhaust grill occupies all the available space around the IEC mains input connector, small mains on/off rocker switch, and model number label. The captive cable set leaves the power supply via a plastic lined port and is sleeved all the way into the unit to protect the cable set from possible damage by the metal enclosure. The modular cable sockets number just four on both models; blue for PCIe or ATX12V/EPS12V (TX750M only) and black for peripherals. The model number is located on the side panels along with comprehensive specifications on the bottom face. The gloss black fan grill, with a Corsair logo at its centre, is internally mounted.

 

 

 

The TX550M captive cable set consists of a 20+4 pin motherboard, 4+4 pin ATX12V/EPS12V, a chain of three 4 pin peripheral connectors, and chain of three SATA connectors. The TX750M captive cable set is almost identical, with the addition of an extra connector on the peripheral and SATA chains, and two 6+2 pin PCIe connector cables.

 

 

The modular cable sets also differ slightly. The TX550M comes with a chain of three 4 pin peripheral connectors, a chain of three SATA connectors, and two 6+2 pin PCI-E connector cables. On the other hand, the TX750W comes with an additional chain of four SATA connectors, two more 6+2 pin PCI-E connector cables, and an extra 4+4 pin ATX12V/EPS12V connector cable. It's worth noting that there are no modular 4 pin peripheral connectors with the TX750M. As well, you cannot use the two modular 6+2 pin PCI-E connectors and the extra 4+4 pin ATX12V/EPS12V at the same time because there are only two blue sockets. If a floppy disk drive is part of the equation, then you will still be catered for, as both units feature an addition of two 4 pin peripheral to 4 pin floppy disk drive adapter cables.

 

 

The cooling fans in both units are good quality Yate Loon D14BH-12 models with dual ball bearing to keep noise to a minimum. The internals, at first glance, are the same though on closer inspection, the primary capacitors differ in value – 330uF in the TX550M and 470uF in the TX750M. This implies the TX750M is upgraded throughout, to cater for the increase in power. The capacitors are all good quality and rated at a working temperature of 105°C.

 

 

The Corsair TX550M and TX750M are well-packaged with a good set of accessories, although a user manual would be welcome if not expected. The build quality is good, but how do they perform? Let's move on and find out.

Specification:

 

Review Samples: Corsair TX550M 550W Power Supply, Part Number CMPSU-550TXM & TX750M 750W Power Supply, Part Number CMPSU-750TXM.

 

Ratings Tables:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corsair TX550M 550W (CMPSU-550TXM) Power Supply Specification Table
AC Input
100V-240V     13A-7.5A     50Hz-60Hz
DC Output
+3V3
+5V
+12V
-12V
+5VSB
Maximum Load
25A
25A
45A
0.8A
3A
Maximum Combined Wattage
140W
540W
9.6W
15W
550W

 

Corsair TX750M 750W (CMPSU-750TXM) Power Supply Specification Table
AC Input
100V-240V     13A-7.5A     50Hz-60Hz
DC Output
+3V3
+5V
+12V
-12V
+5VSB
Maximum Load
30A
30A
62A
0.8A
3A
Maximum Combined Wattage
150W
744W
9.6W
15W
750W

 

System Protection:

 

Corsair TX550M 550W (CMPSU-550TXM) & TX750M 750W (CMPSU-750TXM) System Protection
Over-voltage, under-voltage, over-current and short circuit protection provide maximum safety for your critical components.

 

Safety & Agency Approvals:

 

Corsair TX550M 550W (CMPSU-550TXM) & TX750M 750W (CMPSU-750TXM) EMI & Safety
Safety Approvals
cTUVus, CE, CB, FCC Class B, TUV, CCC, C-tick.

 

Power Supply Physical Characteristics:

 

Corsair TX550M 550W (CMPSU-550TXM) & TX750M 750W (CMPSU-750TXM) Physical & Environmental
Length
Width
Height
6.3in/160mm
5.9in/150mm
3.4in/86mm
Operating Temperature: 50°C.
Mean Time Before Failure (MTBF): 100,000 hours.

 

Power Supply Connectors:

 

Corsair TX550M 550W (CMPSU-550TXM) & TX750M 750W (CMPSU-750TXM) Power Supply Connectors
Connector Type
Qty
 
TX550M
TX750M
20+4 Pin Motherboard
1
1
EPS12V/ATX12V 4+4 Pin
1
2
PCI-E 6+2 Pin
2
4
SATA Power
6
8
Peripheral 4 Pin
6
4
FDD 4 Pin
2
2

 

Power Supply Cable Lengths:

 

Corsair TX550M 550W (CMPSU-550TXM) & TX750M 750W (CMPSU-750TXM) Power Supply
Cable Type
Cable Length/Connector Spacing (±1")
Qty
 
 
TX550M
TX750M
Captive
PSU > 24" > 20+4 Pin Motherboard
1
1
Captive
PSU > 26" > EPS12V/ATX12V 4+4 Pin
1
1
Captive
PSU > 24" > PCI-E 6+2 Pin
 
2
Captive
PSU > 16" > SATA > 6" > SATA > 6" > SATA
1
 
Captive
PSU > 16" > Periph > 6" > Periph > 6" > Periph
1
 
Captive
PSU > 16" > SATA > 6" > SATA > 6" > SATA > 6" > SATA
 
1
Captive
PSU > 16" > Periph > 6" > Periph > 6" > Periph > 6" > Periph
 
1
Modular
PSU > 26" > EPS12V/ATX12V 4+4 Pin
 
1
Modular
PSU > 24" > PCI-E 6+2 Pin
2
2
Modular
PSU > 16" > SATA > 6" > SATA > 6" > SATA
1
 
Modular
PSU > 16" > SATA > 6" > SATA > 6" > SATA > 6" > SATA
 
1
Modular
PSU > 16" > Periph > 6" > Periph > 6" > Periph
1
 
Adapter
Peripheral 4 Pin > 4" > FDD 4 Pin
2
2

 

Features:

 

 

 

All information courtesy of Corsair @ http://www.corsair.com/power-supply-units/enthusiast-series-power-supply-units.html

Testing:

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

Throughout the tables, all passes will be highlighted with green text and failures in red.

 

Short Circuit Protection:

To test this, I short circuited the 3V3, 5V0, and the 12V rail(s). Expectedly, the power supply shut down. Once the short was removed and the unit switched off for at least one second, it 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:

In an ideal world, the ATX power supply, or any other form factor for that matter, should maintain its DC rails at a constant voltage, though this is very difficult to achieve due to variations in the AC mains supply and changing DC load levels. The ATX12V V2.2 specification limits for this variation, expressed as a percentage above or below the ideal voltage, are given in the table below.

 

PSU Rail
Range
Minimum
Nominal
Maximum
+3V3
±5%
+3.14V
+3.30V
+3.47V
+5V
±5%
+4.75V
+5.00V
+5.25V
+12V
±5%*
+11.40V
+12.00V
+12.60V
-12V
±10%
-10.80V
-12.00V
-13.20V
+5VSB
±5%
+4.75V
+5.00V
+5.25V

 

*Note: The +12V rail is permitted to go to ±10% at its rated maximum DC load.*

There is no unit associated with voltage regulation – it is a simple ratio expressed as a percentage:

Voltage regulation VR= ([V no load – V full load] / V full load) x 100%

This equation is used to measure the voltage regulation of a simple single rail power supply but measuring the voltage regulation of the ATX power supply and the difference from the specified rail voltage will require a slightly different tack.

ATX Power Supply regulation = ([V measured - V specified] / V measured) x 100%

This will give the difference as a percentage from the specified rail voltage; +3.3V, +5V, +12V, etc.

There will be very few, if any, power supply failures in this section. The switched mode power supply is very good at maintaining its rail(s) at the correct voltage; they are constantly monitored and any changes are instantly fed back to the control circuitry, with necessary adjustments made to correct any error. So why test? The tighter the regulation the better; ±5% is acceptable, ±3% is very good, and ±2% is excellent. The quality of the regulation is a useful indicator of the power supply’s overall quality.

 

TX550M - Mains Input Voltage 110VAC

 

 

Corsair TX550M 550W (CMPSU-550TXM) DC Output Voltage Load Regulation
Supply = 117VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
0
3.32V
3.3V±5%
+0.6%
+5V
0
5.05V
5.0V±5%
+1.0%
+12V
0
12.10V
12.0V±5%
+0.8%
-12V
0
11.85V
12.0V±10%
-1.3%
+5VSB
0
5.06V
5.0V±5%
+1.2%
Total PSU DC Loading = 0W (0% of Rated Maximum Output Power)

 

Corsair TX550M 550W (CMPSU-550TXM) DC Output Voltage Load Regulation
Supply = 115VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
3.08A
3.28V
3.3V±5%
-0.6%
+5V
4.69A
5.00V
5.0V±5%
0
+12V
5.08A
12.05V
12.0V±5%
+0.4%
-12V
0.34A
11.74V
12.0V±10%
-2.2%
+5VSB
2.05A
4.97V
5.0V±5%
-0.6%
Total PSU DC Loading = 110W (20% of Rated Maximum Output Power)

 

Corsair TX550M 550W (CMPSU-550TXM) DC Output Voltage Load Regulation
Supply = 114VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
7.99A
3.23V
3.3V±5%
-2.1%
+5V
9.51A
4.92V
5.0V±5%
-1.6%
+12V
16.34A
11.94V
12.0V±5%
-0.5%
-12V
0.35A
11.99V
12.0V±10%
0
+5VSB
2.02A
4.87V
5.0V±5%
-2.6%
Total PSU DC Loading = 281W (51% of Rated Maximum Output Power)

 

Corsair TX550M 550W (CMPSU-550TXM) DC Output Voltage Load Regulation
Supply = 113VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
12.68A
3.20V
3.3V±5%
-3.0%
+5V
14.37A
4.87V
5.0V±5%
-2.6%
+12V
33.36A
11.88V
12.0V±5%
-1.0%
-12V
0.36A
12.16V
12.0V±10%
+1.3%
+5VSB
2.00A
4.82V
5.0V±5%
-3.6%
Total PSU DC Loading = 521W (95% of Rated Maximum Output Power)

 

TX750M - Mains Input Voltage 230VAC

 

 

Corsair TX550M 550W (CMPSU-550TXM) DC Output Voltage Load Regulation
Supply = 246VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
0
3.32V
3.3V±5%
+0.6%
+5V
0
5.06V
5.0V±5%
+1.2%
+12V
0
12.10V
12.0V±5%
+0.8%
-12V
0
11.86V
12.0V±10%
-1.2%
+5VSB
0
5.06V
5.0V±5%
+1.2%
Total PSU DC Loading = 0W (0% of Rated Maximum Output Power)

 

Corsair TX550M 550W (CMPSU-550TXM) DC Output Voltage Load Regulation
Supply = 244VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
3.12A
3.28V
3.3V±5%
-0.6%
+5V
4.66A
5.00V
5.0V±5%
0
+12V
5.08A
12.04V
12.0V±5%
+0.3%
-12V
0.34A
11.75V
12.0V±10%
-2.1%
+5VSB
2.05A
4.96V
5.0V±5%
-0.8%
Total PSU DC Loading = 108W (20% of Rated Maximum Output Power)

 

Corsair TX550M 550W (CMPSU-550TXM) DC Output Voltage Load Regulation
Supply = 244VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
7.98A
3.21V
3.3V±5%
-2.7%
+5V
9.35A
4.91V
5.0V±5%
-1.8%
+12V
16.31A
11.94V
12.0V±5%
-0.5%
-12V
0.35A
11.96V
12.0V±10%
-0.3%
+5VSB
2.01A
4.85V
5.0V±5%
-3.0%
Total PSU DC Loading = 280W (51% of Rated Maximum Output Power)

 

Corsair TX550M 550W (CMPSU-550TXM) DC Output Voltage Load Regulation
Supply = 243VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
12.88A
3.18V
3.3V±5%
-3.6%
+5V
14.40A
4.87V
5.0V±5%
-2.6%
+12V
33.75A
11.87V
12.0V±5%
-1.1%
-12V
0.36A
12.20V
12.0V±10%
+1.6%
+5VSB
2.01A
4.81V
5.0V±5%
-3.8%
Total PSU DC Loading = 525W (95% of Rated Maximum Output Power)

 

The Corsair TX550M produced a satisfactory set of results in this section with the three main rails staying within the limits set down by the ATX12V specification with a worst case regulation of -3.3% on the +3.3V rail.

Testing:

TX750M - Mains Input Voltage 110VAC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corsair TX750M 750W (CMPSU-750TXM) DC Output Voltage Load Regulation
Supply = 116VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
0
3.35V
3.3V±5%
+1.5%
+5V
0
5.09V
5.0V±5%
+1.8%
+12V
0
12.13V
12.0V±5%
+1.1%
-12V
0
11.90V
12.0V±10%
-0.8%
+5VSB
0
5.09V
5.0V±5%
+1.8%
Total PSU DC Loading = 0W (0% of Rated Maximum Output Power)

 

Corsair TX750M 750W (CMPSU-750TXM) DC Output Voltage Load Regulation
Supply = 116VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
3.17A
3.33V
3.3V±5%
+0.9%
+5V
4.82A
5.06V
5.0V±5%
+1.2%
+12V
10.18A
12.10V
12.0V±5%
+0.8%
-12V
0.35A
11.85V
12.0V±10%
-1.3%
+5VSB
2.12A
4.88V
5.0V±5%
-2.4%
Total PSU DC Loading = 173W (23% of Rated Maximum Output Power)

 

Corsair TX750M 750W (CMPSU-750TXM) DC Output Voltage Load Regulation
Supply = 113VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
8.19A
3.31V
3.3V±5%
+0.3%
+5V
9.57A
5.01V
5.0V±5%
+0.2%
+12V
23.68A
12.03V
12.0V±5%
+0.3%
-12V
0.35A
12.03V
12.0V±10%
+0.3%
+5VSB
2.00A
4.89V
5.0V±5%
-2.2%
Total PSU DC Loading = 374W (50% of Rated Maximum Output Power)

 

Corsair TX750M 750W (CMPSU-750TXM) DC Output Voltage Load Regulation
Supply = 110VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
13.04A
3.28V
3.3V±5%
-0.6%
+5V
14.89A
4.95V
5.0V±5%
-1.0%
+12V
49.02A
11.95V
12.0V±5%
-0.4%
-12V
0.36A
12.28V
12.0V±10%
+2.3%
+5VSB
2.02A
4.82V
5.0V±5%
-3.6%
Total PSU DC Loading = 716W (95% of Rated Maximum Output Power)

 

TX750M - Mains Input Voltage 230VAC

 

 

Corsair TX750M 750W (CMPSU-750TXM) DC Output Voltage Load Regulation
Supply = 244VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
0
3.35V
3.3V±5%
+1.5%
+5V
0
5.09V
5.0V±5%
+1.8%
+12V
0
12.14V
12.0V±5%
+1.2%
-12V
0
11.90V
12.0V±10%
-0.8%
+5VSB
0
5.09V
5.0V±5%
+1.8%
Total PSU DC Loading = 0W (0% of Rated Maximum Output Power)

 

Corsair TX750M 750W (CMPSU-750TXM) DC Output Voltage Load Regulation
Supply = 244VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
3.17A
3.33V
3.3V±5%
+0.9%
+5V
4.80A
5.06V
5.0V±5%
+1.2%
+12V
10.07A
12.09V
12.0V±5%
+0.8%
-12V
0.35A
11.84V
12.0V±10%
-1.3%
+5VSB
2.12A
4.89V
5.0V±5%
-2.2%
Total PSU DC Loading = 171W (23% of Rated Maximum Output Power)

 

Corsair TX750M 750W (CMPSU-750TXM) DC Output Voltage Load Regulation
Supply = 243VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
7.91A
3.30V
3.3V±5%
0
+5V
9.52A
5.01V
5.0V±5%
+0.2%
+12V
23.76A
12.04V
12.0V±5%
+0.3%
-12V
0.35A
12.00V
12.0V±10%
0
+5VSB
1.99A
4.84V
5.0V±5%
-3.2%
Total PSU DC Loading = 374W (50% of Rated Maximum Output Power)

 

Corsair TX750M 750W (CMPSU-750TXM) DC Output Voltage Load Regulation
Supply = 238VAC/50Hz
PSU DC Rail
Rail Loading
Measured Voltage
Permitted Regulation
Actual Regulation
+3.3V
13.05A
3.27V
3.3V±5%
-0.9%
+5V
14.85A
4.95V
5.0V±5%
-1.0%
+12V
49.05A
11.96V
12.0V±5%
-0.3%
-12V
0.37A
12.31V
12.0V±10%
+2.6%
+5VSB
2.02A
4.83V
5.0V±5%
-3.4%
Total PSU DC Loading = 717W (96% of Rated Maximum Output Power)

 

The Corsair TX750M produced a set of results that are better than that of the TX550M in this section, with the three main rails of the former staying well within the limits set down by the ATX12V specification and a worst case regulation of +1.8% on the +5V rail.

Testing:

Efficiency and Power Factor:

Efficiency is a measure of an ATX power supply’s ability to minimize power loss during the conversion of the AC mains voltage to multiple DC rails. It is a simple ratio of output power measured in watts over input power measured in watts, expressed as a percentage. It has no effect on the power supply’s ability to power a PC, though a higher efficiency brings forth less heat and lower utility bills. It is also “green” and friendlier to the environment, which is the driving force behind the 80 Plus certification program.

Power factor is a strange beast that’s difficult to fully explain without the use of complex AC theory, so let’s keep it simple. Power factor doesn’t have a unit of measurement – it’s a simple number from 0 to 1 that is concerned with the way various loads consume power, where the closer to unity the better. It is closely linked to 80 Plus certification because low power factors imply wasted energy that the normal domestic consumer does not get charged for but the utility companies still have to generate.

TX550M - Supply at 110VAC:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corsair TX550M 550W (CMPSU-550TXM) Efficiency & Power Factor
Supply = 110VAC/50Hz
DC Load (W)
0
110
281
521
DC Load As A Percent Of Max (%)
N/A
20
51
95
Efficiency (%)
N/A
81.5
83
80
Power Factor (PF)
0.57
0.97
0.99
0.99

 

The 80 Plus Bronze certificate requires 82%, 85%, and 82% efficiency at 20%, 50% and 100% DC load, respectively, with a power factor of 0.9 at 50% DC load. The TX550M falls a little short in OCC’s power supply testing methodology, but that isn't unusual. The power factor is well within specification and remained well over 0.9 from 20% to 100% DC loading.

 

TX550M - Supply at 230VAC:

 

 

Corsair TX550M 550W (CMPSU-550TXM) Efficiency & Power Factor
Supply = 230VAC/50Hz
DC Load (W)
0
108
280
525
DC Load As A Percent Of Max (%)
N/A
20
51
95
Efficiency (%)
N/A
82
83
83
Power Factor (PF)
0.13
0.88
0.96
0.98

 

The TX550M produced slightly better efficiency results when supplied from 230VAC and marginally lower power factors overall, although it still remained well over the specified lower limit of 0.9.

 

TX750M - Supply at 110VAC:

 

 

Corsair TX750M 750W (CMPSU-750TXM) Efficiency & Power Factor
Supply = 110VAC/50Hz
DC Load (W)
0
173
374
716
DC Load As A Percent Of Max (%)
N/A
23
50
95
Efficiency (%)
N/A
84
83
78
Power Factor (PF)
0.70
0.99
1.00
0.99

 

The TX750M efficiency, although good, tailed off on the approach to full load, which is unusual. Power factor levels, as usual, maintained above 0.9 at all times, between 20% and 100% DC loading.

 

TX750M - Supply at 230VAC:

 

 

Corsair TX750M 750W (CMPSU-750TXM) Efficiency & Power Factor
Supply = 230VAC/50Hz
DC Load (W)
0
171
374
717
DC Load As A Percent Of Max (%)
N/A
23
50
96
Efficiency (%)
N/A
86
85
82
Power Factor (PF)
0.16
0.92
0.97
0.99

 

Increasing the mains supply to 230VAC produced a slightly better efficiency and marginally reduced power factor levels, as is usually the case.

 

The TX550M and TX750M are both 80 Plus Bronze certified units and apart from an unusual dip in efficiency at approaching full DC load on the TX750M, they both presented satisfactory results. The rail loadings for 80 Plus certification are quite specific and it's difficult to replicate with the OCC power supply testing methodology, so it would be unfair to judge them too harshly in this section. A maximum measured efficiency of 83% on the TX550M and 86% on the TX750M is a satisfactory, although not remarkable, result in this section.

Testing:

TX550M - AC Ripple on DC Outputs:

I have consistently found the AC ripple levels on the DC rails to be more or less equal between an 110VAC and 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 there are any significant differences.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

AC ripple/noise on the +3V3 rail at 230VAC

Oscilloscope settings: Amplitude = 10mV/div, Timebase = 20mS/div

 

AC ripple/noise on the +5V0 rail at 230VAC

Oscilloscope settings: Amplitude = 10mV/div, Timebase = 20mS/div

 

AC ripple/noise on the +12V rail at 230VAC

Oscilloscope settings: Amplitude = 10mV/div, Timebase = 20mS/div

 

AC ripple/noise on the -12V rail at 230VAC

Oscilloscope settings: Amplitude = 10mV/div, Timebase = 20mS/div

 

AC ripple/noise on the +5VSB rail at 230VAC

Oscilloscope settings: Amplitude = 10mV/div, Timebase = 20mS/div

 

Corsair TX550M 550W (CMPSU-550TXM) AC Ripple/Noise
Supply = 230VAC/50Hz DC Loading = 525W
DC Rail
+3V3
+5V0
+12V
-12V0
+5VSB
ATX12 Max (mV p-p)
50
50
120
120
50
Ripple (mV p-p)
38
46
47
95
45
Pass/Fail
Pass
Pass
Pass
Pass
Pass

 

The results in this section are marginal, but still maintained within the limits set down by the ATX12V V2.2 specification – a pass for the TX550M in this section, but only just.

 

TX750M - AC Ripple On DC Outputs:

 

I have consistently found the AC ripple levels on the DC rails to be more or less equal between an 110VAC and 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 there are any significant differences.

 

AC ripple/noise on the +3V3 rail at 230VAC

Oscilloscope settings: Amplitude = 10mV/div, Timebase = 20mS/div

 

AC ripple/noise on the +5V0 rail at 230VAC

Oscilloscope settings: Amplitude = 10mV/div, Timebase = 20mS/div

 

AC ripple/noise on the +12V rail at 230VAC

Oscilloscope settings: Amplitude = 10mV/div, Timebase = 20mS/div

 

AC ripple/noise on the -12V rail at 230VAC

Oscilloscope settings: Amplitude = 10mV/div, Timebase = 20mS/div

 

AC ripple/noise on the +5VSB rail at 230VAC

Oscilloscope settings: Amplitude = 10mV/div, Timebase = 20mS/div

 

Corsair TX750M 750W (CMPSU-750TXM) AC Ripple/Noise
Supply = 230VAC/50Hz DC Loading = 717W
DC Rail
+3V3
+5V0
+12V
-12V0
+5VSB
ATX12 Max (mV p-p)
50
50
120
120
50
Ripple (mV p-p)
49
45
94
95
44
Pass/Fail
Pass
Pass
Pass
Pass
Pass

 

The results in this section are marginal but still maintained within the limits set down by the ATX12V V2.2 specification – a pass for the TX750M as well, but only just.

Testing (Continued):

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 a power supply is installed in a case, which, by the way, it wasn't for testing. Ambient temperatures, 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.

 

TX550M - Temperature, Noise Levels, and Fan Speeds:

 

 

 

 

 

 

 

 

 

 

 

 

Corsair TX550M 550W (CMPSU-550TXM) Temperature & Fan Speeds
Supply = 110VAC/230VAC
DC Loading(W)
Temp In (°C)
Temp Out (°C)
Δ Temp (°C)
Fan Speed (RPM)
0
N/A
N/A
N/A
805/797
110/108
21.5/21.8
24.4/25.2
2.9/3.4
798/798
281/280
22.3/21.2
30.3/29.7
8.0/8.5
802/802
521/525
22.3/22.2
38.9/40.0
16.6/17.8
809/811

 

The TX550M remained cool and quiet at all times, even with the unusual behaviour of the cooling fan that didn't vary throughout testing. The marginal speed increase at full load indicates it was perhaps on the verge of ramping up, though the introduction of a little warmer air into its intake from the load exhaust caused a noticeable increase in speed.

 

TX750M - Temperature, Noise Levels, and Fan Speeds:

Corsair TX750M 750W (CMPSU-750TXM) Temperature & Fan Speeds
Supply = 110VAC/230VAC
DC Loading(W)
Temp In (°C)
Temp Out (°C)
Δ Temp (°C)
Fan Speed (RPM)
0
N/A
N/A
N/A
791/789
173/171
20.9/20.8
24.6/26.2
3.7/5.4
791/793
374/374
21.4/20.9
35.2/32.7
13.8/11.8
798/797
716/717
21.3/21.8
43.4/42.4
22.1/20.6
1499/1553

 

The TX750M remained cool and quiet throughout testing, assisted by the cooling fan maintaining a relatively low speed of only 1500RPM at full load. No problems here, so let's move on.

Conclusion:

TX550M:

 

Price Per Wattage:

Corsair TX550M 550W Power Supply at $89.99 = $0.16/Watt (02-2012)

 

The Corsair TX550M power supply comes well-packaged with good build quality and a decent set of accessories.

The DC voltage load regulation is generally good, with a worst case -3.6% on the +3.3V rail. The noise/ripple values, on the other hand, could be better although it manages to stay within the limits set down by the ATX12V specification, but only just. The efficiency/power factor correction of the TX550M is on a par with other power supplies in this class, as tested by the OCC power supply methodology.

The Corsair TX550M is a decent enough offering that brings the option of modular cables to the ever-popular TX range at a competitive price. It's well made and performs well, so it's certainly capable of reliably powering a powerful gaming PC with a single high end graphics card.

 

Pros:

 

Cons:


 

Conclusion:

TX750M:

Price Per Wattage:

Corsair TX750M 750W Power Supply at $129.99 = $0.24/Watt (02-2012)

 

The Corsair TX750M power supply comes well-packaged with good build quality and a decent set of accessories.

The DC voltage load regulation is generally excellent, with a worst case +1.8% on the +5V rail. Like the TX550M, the noise/ripple values, on the other hand, could be better although they manage to stay within the limits set down by the ATX12V specification, but only just. The efficiency/power factor correction of the TX750M is satisfactory, though there was an unexpected dip at full load on 110VAC to 78% – not what you'd expect from an 80 Plus Bronze certified power supply. In its defence, the rail loadings didn't replicate those used for 80 Plus certification, so it wouldn't be fair to judge it too harshly when tested with OCC’s power supply methodology.

The Corsair TX750M is a decent enough offering that brings the option of modular cables to the ever-popular TX range at a competitive price. It's well made and performs well, so it's certainly capable of reliably powering a powerful gaming PC with two high end graphics cards.

 

Pros:

 

Cons: