Overclockers Club » Corsair TX550M & TX750M Power Supply Review

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
Maximum Combined Wattage	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
Maximum Combined Wattage	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:

A dedicated single +12V rail offers simple configuration and maximum compatibility with the latest graphics cards and other components
An ultra-quiet, 140mm double ball-bearing fan delivers excellent airflow with exceptionally low noise levels by varying fan speed in response to temperature
Complies with the European Union ErP Directive (2009/125/EC) so the power consumption of the whole system, in either standby or off mode, can be less than 1W when used with a properly configured, ErP-compliant motherboard
80 PLUS Bronze certified, delivering up to 85% energy efficiency under real-world load conditions
Active Power Factor Correction (PFC) with PF value of 0.99
Universal AC input from 90~264V
Over-voltage, under-voltage, over-current, and short circuit protection provide maximum safety for your critical system components
High-quality capacitors provide uncompromised performance and reliability
A five year warranty and lifetime access to Corsair's legendary technical support and customer service

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.