Corsair 750W Enthusiast Series Modular PSU Review (TX750M)

1. Introduction2. Corsair TX750M (Bundle & Cables)3. Corsair TX750M (External)4. Corsair TX750M (Internal)5. Corsair TX750M (Super High Res Gallery)6. Testing Methodology and Results7. Closing Thoughts8. View All Pages

Additional technical assistance: Peter McFarland and Jeremy Price.

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. Due to public requests we have changed our temperature settings recently – previously we rated with ambient temperatures at 25C, we have increased ambient temperatures by 10c (to 35c) in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:
•  SunMoon SM-268
•  CSI3710A Programmable DC load (+3.3V and +5V outputs)
•  CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• Extech digital sound level meter
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
75W	1.24	3.37	1.17	5.06	4.92	12.14	0.50	5.04	0.20	-12.05
150W	2.19	3.35	2.81	5.04	10.03	12.09	1.00	5.03	0.30	-12.05
375W	6.13	3.30	6.02	5.02	26.12	12.06	1.50	5.01	0.50	-12.06
565W	10.32	3.28	10.83	4.99	38.32	12.04	2.00	4.98	0.60	-12.07
750W	10.71	3.27	13.82	4.97	53.56	11.97	3.00	4.95	0.80	-12.08

The Corsair power supply has strong load regulation, with only minor deviation. These are great results and the rails remained firmly within +/-3% of the nominal voltage.

Corsair TX750M	Maximum Load
	824W

We managed to reach around 824W before the unit would shut down gracefully, after the protection kicked in.

Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.

Cross Load Testing	+3.3V		+5V		+12V		-12V		+5VSB
	A	V	A	V	A	V	A	V	A	V
734W	1.0	3.34	1.0	5.03	60.0	11.96	0.2	-12.05	0.50	5.03
154W	15.0	3.28	15.0	4.95	2.0	12.11	0.2	-12.05	0.50	4.99

Fluctuation is held safely within the rated parameters, even when we load the 12V line with 60A.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum.

ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Output	Ripple (mV p-p)
+3.3V	50
+5V	50
+12V1	120
+12V2	120
-12V	120
+5VSB	50

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load	+3.3V	+5V	+12V	5VSB
75W	10	10	10	10
150W	10	10	15	10
375W	15	15	20	15
565W	15	15	30	15
750W	20	20	35	15

Ripple results are very good on all the rails, holding well within the tolerance guidelines. The 12V+ output is particularly impressive, peaking at 35 mV.

Efficiency (%)
75W	84.21
150W	87.87
375W	88.69
565W	87.21
750W	85.89

The Corsair is very efficient for an 80 Plus Bronze rated unit, peaking at just under 89 percent efficency at 50 percent load.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the power supply we have taken it into our acoustics room environment and have set our Digital Sound Level Noise Decibel Meter Style 2 one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refridgerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 Player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

Noise (dBA)
75W	27.9
150W	27.9
375W	28.2
565W	32.9
750W	35.8

This power supply is extremely quiet, registering at the lowest limits of our equipment, until loaded to around 50% of the total output. It becomes audible in the last 20% of the maximum power figure.

Temperature (c)
	Intake	Exhaust
75W	36	39
150W	38	41
375W	39	45
565W	43	49
750W	44	51

Exhaust temperatures are impressive, reaching a maximum delta of 7c above intake at full load.

Maximum load	Efficiency
824W	84.2

For those interested, we measured efficiency when stressing the unit to breaking point. 84.2 percent efficiency at 824W … hardly practical, but interesting regardless.

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