Reviews - Corsair TX750W Power Supply Review
Sample Provided by: Corsair (By Oklahoma Wolf - madmat on Tue, Oct-16-2007)

Page 2 -
     Now that we've heard from Oklahoma Wolf and his merry band of flaming beavers let's take a look at the performance of the TX750W.

     First I'd like to take a moment to cover my testing methodology: For testing I'm using a SunMoon SM-268+ ATE (active test equipment) to load up to six rails at five preset loads. I'm also using a USB Instruments DS12M Stingray USB O-scope to log the ripple which I'm saving as an image file. I used to run five tests as the SM-268 has five preprogrammed tests but I've expanded this to include high 3.3V/5V cross load and high 12V cross load testing. Test six is the high 3.3V/5V cross load and test seven is the high 12V cross load.

     Now that we have that out of the way let's take a look at how the TX750W does in an open environment.

Results from Corsair TX750W COLD load tests
Test # +3.3V +5V +12V AC Watts/
DC Watts
Eff. P.F. Intake / Exhaust
Simulated system load tests
Test
1
3A 4A 6A 149W/
119.7W
80% .97 25°C / 32°C
3.36V 5.10V 12.17V
Test
2
5A 8A 10A 235W/
195.0W
83% .98 24°C / 34°C
3.34V 5.09V 12.15V
Test
3
8A 10A 26A 481W/
407.7W
85% .99 24°C / 38°C
3.30V 5.06V 12.10V
Test
4
13A 15A 45A 825W/
674.8W
82% .99 22°C / 41°C
3.24V 5.02V 12.03V
Test
5
16A 17A 50A 931W/
752.9W
81% .99 22°C / 45°C
3.21V 5.00V 12.01V
Test
6
18A 25A 2A 294W/
224.0W
76% .99 27°C / 44°C
3.27V 5.02V 12.13V
Test
7
1A 1A 60A 910W/
745.9W
82% .99 27°C / 44°C
3.29V 5.05V 12.03V

     Not bad really. The efficiency is fairly high throughout all the tests aside from the high 3.3V/5V test which isn't unusual. These new power supplies are better suited to high 12V loads which makes a lot of sense considering that they're designed to deal with modern PC's. The voltage regulation isn't as good as the VX550W but it's also pushing considerably more power. The 3.3V rail takes the worst beating during the heavy loads while the 12V rail and 5V rail hold up very well. What does this translate into for the end user? The short and sweet is that the CPU and video card(s) will have minimal voltage droop under all loads while the ram will see more voltage droop. The voltage regulation circuitry for the CPU will have an easier time since it won't have to make up for as much 12V drop while the regulation circuit for the ram might run a tad warmer. Is this a major problem? No, not really, with ram we're talking about just a few watts so the heat increase will be minimal whereas the CPU Vregs pass a lot of current and in the world of voltage regulation when the available voltage drops the Vregs make up for it by moving more current. In the end the same amount of work is being performed since V * A = W but passing more amperage is harder on semiconductors than passing more voltage.

     The efficiency is at or above 80% in all the tests aside from test 6. Test 6 is par for the course with modern PSU's  so I'm not going to ding it for that. The peak of 85% is pretty good, not class leading but pretty close to it.

     This unit is also a CWT build like the VX550W and as such it has the clear baffle covering half the fan. As we can see the temp delta between the intake and exhaust is again pretty high and I noticed a huge amount of inversion coming from the fan. The airflow from the rear of the unit was also very weak even during tests 4-7 when the fan sounded like it was at full speed. I just don't think that the baffle is allowing the unit to be adequately cooled.

     Let's pop this puppy in the hotbox and see how it likes it.

Results from Corsair TX750W HOT load tests
Test # +3.3V +5V +12V AC Watts/
DC Watts
Eff. P.F. Intake / Exhaust
Simulated system load tests
Test
1
3A 4A 6A 150W/
119.4W
80% .97 27°C / 29°C
3.34V 5.10V 12.16V
Test
2
5A 8A 10A 237W/
194.7W
82% .98 31°C / 35°C
3.32V 5.08V 12.14V
Test
3
8A 10A 26A 485W/
408.1W
84% .99 37°C / 44°C
3.28V 5.06V 12.11V
Test
4
13A 15A 45A 828W/
675.9W
82% .99 41°C / 54°C
3.21V 5.01V 12.05V
Test
5
16A 17A 50A 939W/
754.0W
80% .99 44°C / 62°C
3.19V 4.99V 12.03V
Test
6
18A 25A 2A 298W/
224.4W
75% .99 40°C / 51°C
3.26V 5.02V 12.13V
Test
7
1A 1A 60A 917W/
749.4W
82% .99 42°C / 57°C
3.29V 5.05V 12.08V

     Largely the TX750W seems to shrug off the hotbox at least until the full load test rolls around. By then the 3.3V rail is .11V under spec and .15V down from test 1. That's about a 4% drop which is still within spec but  it's still a bit more than I like to see. Strangely the 5V rail hangs in with just an average of .01V drop over the cold tests while the 12V rail picks up a bit. We see the efficiency drop a point here and there but it still stays above 80% in everything but test 6. Although, it's not a situation you're likely to encounter with a real PC unless you're using an old school processor with one drive. In that case you'd most likely not be looking into a 750W PSU.

     On the cooling front the TX750W starts out looking better than the cold test but as the heat comes up in the hotbox we start seeing the temp delta begin to grow. Guys, please, lose the baffle! It's not helping.

Let's take a look at the ripple.


Corsair TX750W +3.3V +5V +12V
Test 1
Test 2
Test 3
Test 4
Test 5
Test 6
Test 7


     On the ripple front we start out with the 3.3V and 5V rails looking awesome. 14mV is sweet. The 12V rail has a bit more and continues to climb until it maxes at around 100mV in test 7. The 3.3V and 5V rails stay calm, cool and collected until test 6 when the 5V rail breaks into a little dance number and pops into a downward spike every 8ms or so. At that point it's about 80mV which is well above the 50mV spec. Lowering the 3.3V amperage had no effect but dropping the 5V rail to 23A did away with the warble. So much for the 28A rating. Test 6 aside the TX750W does really well. with all the rails staying within spec and the 3.3V and 5V rails staying extra clean.


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