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Corsair TX650W ATX12V power supply

March 16, 2008 by Mike Chin

Product
Corsair TX650W

ATX12V v2.2 power supply
Manufacturer
Corsair Memory
Market Price
US$100~140

Corsair doesn't have to be introduced as a power supply brand any more, as they've made such a splash since first entering this market in 2006 with the modular cable HX series. In 2007, they introduced four more power supply models: The VX450 and VX550, followed by the TX650 and TX750. All of these have non-detachable cables. We reviewed the VX450 not long ago, and gave it two thumbs up: It's another high quality, quiet PSU made for Corsair, again, by Seasonic. Interestingly, the TX650 is also made by Seasonic, but the VX550 and TX750 are both made by Channel Well. It's not clear why different suppliers were used for these various models.

The TX650W reflects the escalating power trend among enthusiast computer users, driven mostly by power-hungry graphics cards. Its 650W rating is considered mid-range by extreme gamers today. Interestingly, Corsair's marketing makes a big deal about the unit's single 12V line, in contrast to so many other brands which tout multiple 12V lines. As with all the Corsair power supplies introduced in 2007, the TX650 is 80 Plus certified, which assures 80% or higher efficiency from 20% load on up to full power. The packaging is similar to the HX and VX series, with a classy, understated look. The TX750 differs visibly in that it has a 140mm fan instead of the other VX and TX models' more common 120mm fan.




Classy understated retail package.



Inside, the PSU is cradled in a cloth drawstring bag lined with bubble-plastic. A user's manual, screws, plastic cable straps, AC cable and a detailed reviewer's guide completed the sample package.
(Note: TX750W shown; TX650W pacakage is identical.)

FEATURE HIGHLIGHTS AND SPECIFICATIONS

Corsair TX650W Feature Highlights (from the Corsair
web site)
FEATURE & BRIEF COMMENT
Supports the latest ATX12V v2.2 standard and is backwards compatible with ATX12V 2.01 systems.
Fairly standard for a high end PSU.
Ultra-quiet 120mm double ball-bearing fan delivers excellent airflow All three Corsair models tested so far have delivered on this promise.
80%+ energy efficiency at 20%, 50% and 100% load condition for less heat generation and lower energy bill
Standard for any 80 Plus PSU.
Active Power Factor Correction with PF value=0.99 provides clean and reliable power to your system. >0.9 PC is required by 80 Plus; Active correction is the only way to achieve it.
Universal AC input 90~264V automatically scans and detects the correct voltage. No more hassle of flipping that tiny red switch!
Fairly standard, but the 90V input is lower that the usual 100V, which is good.
Dedicated single +12V rail offers maximum compatibility with latest components. Straight-up honesty as with the VX series.
High quality Japanese capacitors provide uncompromised performance and reliability.
To assure savvy buyers who may be aware of the bad cap fiasco that's plagued China-made electronics for some years.
NVIDIA SLI™-ready certified. Maybe a good assurance for gamers... but a PSU not certified by nVidia doesn't mean it can't do SLI.
Over Current/Voltage/Power Protection, Under Voltage Protection, and Short Circuit Protection provide maximum safety for your critical system components. About par for the high end course.
Size: 5.9"(W) x 3.4"(H) X 5.5"(L)

150mm(W) x 86mm(H) x 150mm(L)
Modestly sized is better than oversized.
MTBF: 100,000 Hours That's a long time. Wonder how it's calculated...
Safety Approvals: UL, CUL, CE, CB, FCC Class B, TÜV, CCC, C-tick. The more the merrier.
Five year warranty with 24/7 support. Very nice.

OUTPUT SPECIFICATIONS: Corsair TX650W
AC Input
90-264VAC, 5-9A, 47-63Hz
DC Output
+3.3V
+5V
+12V
-12V
+5VSB
Maximum Output Current
24A
30A
52A
0.8A
3A
Maximum Combined
170W
624W
9.6W
15W
650W

As with their other PSUs, Corsair provides two graphs that show noise and efficiency curves with a high degree of resolution. Most similar data presented in marketing materials don't really tell much; these are much better than usual.

The noise curve above show a steady noise level of around 21 dBA (at 1m, presumably), and a hinge starting at 325W, at which point the noise rises fairly quickly. We have to assume that the load refers to typical temperatures reached at the plotted power levels, since every PSU we've tested only ties fan speed to temperature, not actual power output. Ambient temperature during the test has a strong impact on noise behavior, but this data is not provided.

The efficiency curves shown above are also very detailed and show a realistic midrange peak with falloff at either extremes. The 2~4 percentage point advantage in efficiency at 230VAC jibes perfectly well with our own comparison tests of PSU efficiency at 120 VAC versus 240 VAC.

EXTERNAL TOUR

The exterior of the TX650W is archetypical black.



Nothing out of the ordinary here.



No vents
other than the fan intake and...



...backside exhaust grill.



The label.

We know that Seasonic is the manufacturer, but the E307858 UL file number marked on the label is registered to Corsair.

OUTPUT CABLES

They are long and plentiful. There are a total of eight cable sets, all neatly sleeved:

  • 22" cable for main 20+4-pin ATX connector
  • 22" cable for 2/4-pin 12V AUX12V
  • 2 x 24" cable for 6/8-pin PCIe connector - for the latest most power hungry graphics cards
  • 2 x 37" cable with four 4-pin IDE connectors and one floppy drive connector
  • 2 x 32" cable with four SATA drive connectors

 



All the output cables are sleeved.

INTERIOR

The internal layout of the components on the PCB is tidy. The black heatsinks are reminiscent of those used in Seasonic Tornado or first generation S12 power supplies.



Nice clean layout.



Heatsinks are reminiscent of those used in earlier Seasonic models.



High quality Japanese capacitors are used, rated for 105°C as in previous Corsairs.

The high speed ball bearing fan is made by Adda, similar to others used in many PSUs. Model AD1212HB-A71GL is rated for 89CFM and 39 dBA at 2200RPM and 12V. Judging from previous Corsair PSUs, the fan controller will keep it from getting anywhere close to full speed except under sustained full load.



Familiar Adda fan.

TESTING

For a fuller understanding of ATX power supplies, please read the reference
article Power Supply Fundamentals & Recommended
Units
. Those who seek source materials can find Intel's various PSU
design guides at Form
Factors
.

For a complete rundown of testing equipment and procedures, please refer to
SPCR's PSU Test Platform
V.4.1
. The testing system is a close simulation of a moderate airflow
mid-tower PC optimized for low noise.

In the test rig, the ambient temperature of the PSU varies proportionately
with its output load, which is exactly the way it is in a real PC environment.
But there is the added benefit of a high power load tester which allows incremental
load testing all the way to full power for any non-industrial PC power supply.
Both fan noise and voltage are measured at various standard loads. It is, in
general, a very demanding test, as the operating ambient temperature of the
PSU often reaches >40°C at full power. This is impossible to achieve
with an open test bench setup.

The 120mm fan responsible for "case airflow" is deliberately run
at a steady low level (~6-7V) when the system is run at "low" loads.
When the test loads become greater, the 120mm fan is turned up to a higher speed,
but one that doesn't affect the noise level of the overall system. Anyone who
is running a system that draws 400W or more would definitely want more than
20CFM of airflow through their case, and at this point, the noise level of the
exhaust fan is typically not the greatest concern.

Great effort has been made to devise as realistic an operating
environment for the PSU as possible, but the thermal and noise results obtained
here still cannot be considered absolute. There are too many variables in PCs
and too many possible combinations of components for any single test environment
to provide infallible results. And there is always the bugaboo of sample variance.
These results are akin to a resume, a few detailed photographs, and some short
sound bites of someone you've never met. You'll probably get a pretty good overall
representation, but it is not quite the same as an extended meeting in person.

REAL SYSTEM POWER NEEDS: While our testing loads the PSU to full output
(even 600W!) in order to verify the manufacturer's claims, real desktop PCs
simply do not require anywhere near this level of power. The most pertinent
range of DC output power is between about 40W and 300W, because it is the power
range where most systems will be working most of the time. To illustrate this
point, we conducted system tests
to measure the power draw of several actual systems under idle and worst-case conditions.
Our most power-hungry overclocked 130W TDP processor
rig with an ATI Radeon X1950XTX-512 graphics card drew ~256W DC peak from the power supply under
full load — well within the capabilities of any modern power supply. Please
follow the link provided above to see the details. It is true that very elaborate
systems with the most power hungry dual video cards today might draw as much as another
150W, but the total should remain under 500W in extrapolations of our
real world measurements.

SPCR's high fidelity sound
recording system
was used to create MP3 sound files of this PSU. As
with the setup for recording fans, the position of the mic was 3" from the exhaust
vent at a 45° angle, outside the airflow turbulence area. The photo below shows
the setup (a different PSU is being recorded). All other noise sources in the
room were turned off while making the sound recordings.

INTERPRETING TEMPERATURE DATA

It important to keep in mind that fan speed varies with temperature,
not output load. A power supply generates more heat as output increases, but
is not the only the only factor that affects fan speed. Ambient temperature
and case airflow have almost as much effect. Our test rig represents a challenging
thermal situation for a power supply: A large portion of the heat generated
inside the case must be exhausted through the power supply, which causes a corresponding
increase in fan speed.

When examining thermal data, the most important indicator of cooling efficiency
is the difference between intake and exhaust. Because the heat
generated in the PSU loader by the output of the PSU is always the same for
a given power level, the intake temperature should be roughly the same between
different tests. The only external variable is the ambient room temperature.
The temperature of the exhaust air from the PSU is affected by several factors:

  • Intake temperature (determined by ambient temperature and power output level)
  • Efficiency of the PSU (how much heat it generates while producing the required
    output)
  • The effectiveness of the PSU's cooling system, which is comprised of:
    • Overall mechanical and airflow design
    • Size, shape and overall surface area of heatsinks
    • Fan(s) and fan speed control circuit

The thermal rise in the power supply is really the only indicator
we have about all of the above. This is why the intake temperature is important:
It represents the ambient temperature around the power supply itself. Subtracting
the intake temperature from the exhaust temperature gives a reasonable gauge
of the effectiveness of the power supply's cooling system. This is the only
temperature number that is comparable between different reviews, as it is unaffected
by the ambient temperature.

TEST RESULTS

Note that even though the TX650W has only one 12V line, two separate load banks were used for the 12V loading. The SPCR load tester does not have the capacity to load up 50A on a single 12V line. Hence the 12V1 and 12V2 columns.

OUTPUT, VOLTAGE REGULATION & EFFICIENCY: Corsair TX650W

DC Output Voltage (V) + Current (A)

Total DC Output

AC Input

Calculated Efficiency
+12V1
+12V2
+5V
+3.3V
-12V
+5VSB
12.10
0.96
12.10
0
5.01
0.97
3.38
0.96
0.1
0.1
21.4
34
62.9%
12.10
0.93
12.10
1.71
5.01
0.97
3.38
0.96
0.1
0.1
41.5
59
70.9%
12.10
2.74
12.10
1.71
5.01
1.94
3.38
0.96
0.1
0.3
64.3
81
77.5%
12.07
2.82
12.07
1.71
4.99
2.85
3.38
1.79
0.2
0.5
89.4
109
81.9%
12.07
4.32
12.07
4.90
4.99
2.85
3.38
3.58
0.2
0.7
150.0
184
81.6%
12.04
5.82
12.04
6.52
4.99
4.45
3.36
5.10
0.4
1.0
199.3
241
83.1%
12.00
7.91
12.00
8.01
4.98
6.98
3.35
7.17
0.7
1.5
250.2
304
82.3%
12.00
9.34
12.00
9.59
4.98
6.99
3.34
8.21
0.7
1.5
301.8
361
83.6%
11.90
12.64
11.90
12.80
4.96
7.84
3.32
9.06
0.7
1.9
403.9
499
80.9%
11.90
16.00
11.90
16.83
4.90
10.47
3.27
10.73
0.7
2.4
510.7
636
80.3%
11.83
15.50
11.83
26.50
4.85
12.71
3.22
12.78
0.7
3.0
651.0
824
80.6%
Crossload Test
11.96
18.70
11.96
29.00
4.97
0.98
3.39
0.9
0.1
0.1
580.2
720
82.3%
+12V Ripple (peak-to-peak): 15mV @ 200W ~ 94mV @ 651W (max)
+5V Ripple (peak-to-peak): 12mV @ 200W ~ 26mV @ 651W (max)
+3.3V Ripple (peak-to-peak): 11mV @ 200W ~ 19mV @ 651W (max)
NOTE: The current and voltage for -12V and
+5VSB lines is not measured but based on switch settings of the DBS-2100
PS Loader. It is a tiny portion of the total, and potential errors arising
from inaccuracies on these lines is <1W.


OTHER DATA SUMMARY: Corsair TX650W
DC Output (W)
21.4
41.5
64.3
89.4
150.0
199.3
250.2
301.8
403.9
510.7
651.0
Intake (°C)
22
22
22
24
27
32
32
32
34
38
46
Exhaust (°C)
28
28
30
33
37
47
51
52
54
59
72
Temp Rise (°C)
3
3
4
7
10
15
19
20
20
21
30
Fan Voltage (V)
3.78
3.78
3.78
3.78
3.78
3.85
3.91
4.83
8.81
11.1
11.2
SPL ([email protected])
21
21
21
21
21
21
21
23
38
43
44
Power Factor
0.93
0.99
0.98
0.99
0.99
0.99
1.00
1.00
0.99
1.00
1.00

AC Power in Standby: 0.5W / 0.124 PF

AC Power with No Load, PSU power On: 18.3W / 0.71 PF
NOTE: The ambient room temperature during
testing can vary a few degrees from review to review. Please take this
into account when comparing PSU test data.


ANALYSIS

1. EFFICIENCY — This is a measure of AC-to-DC conversion efficiency. The ATX12V Power Supply Design Guide recommends 80% efficiency or better at all output power loads. 80% efficiency means that to deliver 80W DC output, a PSU draws 100W AC input, and 20W is lost as heat within the PSU. Higher efficiency is preferred for reduced energy consumption and cooler operation. The latter allows reduced cooling airflow, which translates to lower noise.

Even at the super low output load of just 21.4W, the efficiency of the TX650 was a reasonably high 62.9%. This is slightly better than the 61% of the VX450W and compares very favorably with the HX620W's 49.5% efficiency at the same power load. Nearly 82% efficiency was seen at 90W output; the benchmark 80% efficiency probably reached around 75W or 80W. The peak of ~84% was centered at about 300W, and >80% efficiency was maintained, just barely, to full rated 650W output.

2. VOLTAGE REGULATION refers to how stable the output voltages are under various load conditions. The ATX12V Power Supply Design Guide calls for the +12, +5V and +3.3V lines to be maintain within ±5%. At virtually all loads, all the voltages were just about dead on, within a minuscule -0.2V and +0.1V range on the 12V line. The voltage drop during the extreme crossloading test was just as good.

3. AC RIPPLE refers to unwanted "noise" artifacts in the DC output of a switching power supply. It's usually very high in frequency (in the order of kilohertz or megahertz). The peak-to-peak value is measured. The ATX12V Guide allows up to 120mV (peak-to-peak) of AC ripple on the +12V line and 50mV on the +5V and +3.3V lines. Ripple stayed very low, under 15mv on all lines, until about the 200W output level.
Beyond this point, it increased in direct proportion to power putput, and reached a fairly high 94 mV on the 12V line at full load. This is still less than the maximum 120 mV ripple recommended by ATX12V. The higher than expected ripple may be related to our sample's thermal behavior.

4. POWER FACTOR is ideal when it measures 1.0. In the most practical sense, PF is a measure of how "difficult" it is for the electric utility to deliver the AC power into your power supply. High PF reduces the AC current draw, which reduces stress on the electric wiring in your home (and elsewhere up the line). It also means you can do with a smaller, cheaper UPS backup; they are priced according to their VA (volt-ampere) rating. PF on this sample was excellent thanks to the active power factor correction
circuit, staying at or very close to the theoretical maximum of 1.0.

5. LOW LOAD TESTING revealed no problems starting at very low loads, with standby
coming at a half watt, and no-load at 18.3W. Our sample had no issue starting up with no load at all.

6. LOW AND 240 VAC PERFORMANCE

The power supply was set to 500W load with 120VAC through the hefty variac in the lab. The variac was then dialed 10V lower every 10 minutes. This is to check the stability of the PSU under brownout conditions where the AC line voltage drops from the 110~120V norm. The TX650W is rated for operation 90~260VAC, a wider range than the usual 100~240VAC. Most power supplies achieve higher efficiency with higher AC input voltage. SPCR's lab is equipped with a 240VAC line, used to check power supply efficiency for the benefit of those who live in 240VAC mains regions.

Low VAC Test: Corsair TX650W @ 500W Output
VAC
AC Current
AC Power
Efficiency
242V
2.50A
601W
83.2%
120V
5.18A
622W
80.2%
110V
5.68A
627W
79.8%
100V
6.31A
630W
79.4%
90V
7.04A
634W
78.9%

The TX650W demonstrated no problems with the low voltage test. Neither voltage regulation
nor ripple changed measurably during the test, and efficiency dropped only marginally. Efficiency improved with 240VAC input, around 3 percentage points at 500W; Corsair's claim of 86% peak efficiency with 240VAC input at ~50% load is perfectly believable.

7. TEMPERATURE & COOLING

Our sample reached considerably higher temperatures than usually encountered, starting at around the 200W mark, where the temperature rise through the unit reached 15°C. With a majority of quiet PSUs that have been tested on the same platform, the temperature rise at this level tends to be around 10°C. The Corsair VX450W and the Seasonic S12II-380, for examples, both had a temp rise of 11°C at this load. Both intake and exhaust temperatures rose a bit faster and higher than in most other PSUs. The exhaust air temperature exeeded 50°C at just 250W and rose to over 70°C after about 15 minutes at continuous full load. This seems a bit too hot for comfort, although nothing untoward occurred; the only related "misbehavior" was the somewhat higher than normal ripple at full power. Admittedly the chance of a desktop PC actually demanding 650W sustained power for any length of time other than a momentary peak (with the most excessively power-hungry components) is extremely remote.

8. FAN, FAN CONTROLLER and NOISE

The PSU fan stabilized at 3.78V within a couple minutes after turn on. The Sound Pressure Level (SPL) reading was 21 [email protected], audible at 1m, but quiet and smooth.
There was no audible buzzing from a meter away. There was none at this distance above the fan noise at any load. When the fan was stopped with a plastic wire tie jammed into the blades, a bit of buzzing could be heard from under a foot away, but this was about at the same level as fanless PSUs we've tested. In other words, audible buzzing or humming was not an issue.

The fan noise and voltage remained essentially unchanged in our thermal test rig all the way to over 250W output load. This is extremely quiet performance, close to the very best we've encountered in any PSU.

Beyond 250W, the fan speed and noise climbed quickly, as expected. The overall noise up 300W load matched that measured on our Corsair HX520/620 and Enermax Modu82+ 625 samples, the quietest in our database. In the comparison table below, the >30 [email protected] readings are highlighted in light green.

Comparison: Various PSUs Noise Vs. Power Output
Model
90W
150W
200W
250W
300W
400W
500W
600W
Corsair TX650W
21
21
21
21
23
38
43
44
Corsair VX450W
21
21
21
22
26
44
50
n/a


Enermax Modu82+ 625

19
19
20
21
22
26
36
37
Corsair HX520/620
22
22
22
22
22
29
40
40
Seasonic S12 E+ 650
20
20
20
21
26
38
40
40
Seasonic S12II-380
21
21
21
25
31
39
n/a
n/a

Antec EW 430
22
22
24
29
37
41
43
43

Zalman ZM600
25
27
29
30
31
36
40
40

The above comparison table should not be taken as an absolute. It shows sound pressure levels recorded on SPCR's test platform. The ambient temperature varies a bit, in a range of 20~23°C, and some of the PSUs may have the small advantage of lower ambient temperature during testing. This can help lower the overall noise curve, and more importantly, increase the power level at which the fan starts getting seriously louder. Still, at higher power levels, the temperature in the test box is determined mostly by the load. Several models are about equally quiet up to ~200W load. The Corsair HX series, the Enermax Modu82+ 625 and this TX650W have the lowest measured SPL at 300W. At 400W and above, the Enermax is considerably quieter than all but the Corsair HX series.

If you want the best noise performance from the TX650W, use it in a system that draws no more than ~350W DC or about 400W (AC) at the wall. Ensure that the room ambient temperature stays under 30°C. Note that 32°C was the air temperature at the intake side of the TX450W with 300W load. Given the tendency to higher operating temperature, pay close attention to effective case cooling airflow.

MP3 SOUND RECORDINGS

These
recordings were made with a high resolution, studio quality, digital
recording system, then converted to LAME 128kbps encoded MP3s. We've
listened long and hard to ensure there is no audible degradation from
the original WAV files to these MP3s. They represent a quick snapshot
of what we heard during the review. Two recordings of each noise level
are made in some cases, one from a distance of one meter,
and another from one foot away. More details about how we make these recordings can be found in our short
article: Audio
Recording Methods Revised
.

The
one meter recordings
are intended to give you an idea of how the subject
of this review sound in actual use — one meter is a reasonable typical
distance between a computer or computer component and your ear. The
recording contains stretches of ambient noise that you can use to judge
the relative loudness of the subject. Be aware that
very quiet subjects may not be audible — if we couldn't hear it from
one meter, chances are we couldn't record it either!

The
one foot recordings
are designed to bring out the fine details of the
noise. Use this recording with caution! Although more detailed, it may
not represent how the subject sounds in actual use. It is best to
listen to this recording after you have listened to the one meter
recording.

Each recording starts with 6~10 seconds of room ambience, followed by 10 seconds of
the product's noise. For the most realistic results, set the volume
so that the starting ambient level is just barely audible.

Sound Recordings of PSU Comparatives


CONCLUSIONS

The Corsair TX650W is aimed at the dual-video card, power-demanding, PC gaming user. It hits the target smack in the center. The rated power may be a bit lower than what the uber gamers seek, but that's usually more about bragging rights and pseudo-machismo than actual need. Its voltage regulation is excellent, its acoustics very quiet, and its efficiency very good. The AC ripple on the 12V is bit higher (only at full power) than we've seen from Corsair models in the past, but still within the ATX12V spec. Corsair's five year warranty remains the longest for any computer power supply we know of. It sits nicely along with the HX520 and HX620 models, which it essentially matches for acoustics.

The TX650W doesn't quite reach the acoustics and performance heights of the recently reviewed Enermax Modu82+ 625W, but it comes close. It also doesn't have the convenient detachable cables of the HX or Modu82+ series. Price and availability, however, may often be the determining factor when choosing among the top ranked PSUs in our Recommended PSUs. The TX650 certainly belongs near the top of that list. Corsair's pricing also seems quite aggressive; at publication time, there were rebates on the web for the TX650 which broght the final price down to just $75.

The best way to take advantage of the TX650W's quiet qualities has already been mentioned: Ensure that the PSU intake air does not exceed 30°C often, nor demand more than ~350W DC output. With a decent case and well selected components, these requirements are not difficult to achieve. Following these guidelines will reward you with a PSU that's always very quiet, making the basis for a very quiet computer.

Much thanks to Corsair Memory for this review sample.

* * *

SPCR Articles of Related Interest:

Power Supply Fundamentals

Recommended
Power Supplies

Power Distribution within Six PCs

SPCR PSU Test Rig V.4

Seasonic S12 Energy Plus 550 and 660

Zalman ZM600 heatpipe-cooled modular PSU

Seasonic M12-700

Corsair HX520 & HX620

* * *

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this article in the SPCR Forums.

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