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# Corsair TX550M & TX750M Power Supply Review

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## Testing:

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.

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:

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.

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