Corsair TX850w ATX PSU Page: 1

Corsair LogoCorsair have certainly made quite a name for themselves in the PSU market over the past few years, with models such as the HX520 and HX620 being immensely popular among enthusiasts for their sturdy power output, sexy modular design and affordable pricing. This reputation was further reinforced with the release of the HX1000 that took all of these features, added some heavily over-specced internal components and conservatively-labeled the power output as 1000W on a unit that could easily push out so much more.

However, today we're going to be taking a look at one of the PSU's from Corsair's newer TX family. Aimed at the budget-conscious enthusiast, the TX is essentially the HX's hard-wired brother and is available in many of the wattage output ranges that the HX series negated to fill. Here's what Corsair have to say:

Advanced Technology, High Performance
The Corsair TX power supplies are engineered using advanced technology and components typically found with high performance power supplies. With design features such as a dedicated, single +12V rail offer the maximum compatibility with the latest system components. Energy efficient circuitry capable of delivering greater than 80% efficiency ratings across 20%, 50%, and 100% load conditions make the TX family of PSUs ideal for the value/quality conscious enthusiast. With a large 140mm (120mm on TX650W) diameter temperature-controlled fan that is ultra quiet, yet still more than sufficient to cool the internals of the system, reliability and stability are no longer worries for the gamer, overclocker or enthusiast and high-end system builder.

Corsair TX Series Features
* Supports ATX12V v2.2 standard and older ATX12V 2.01 spec
* Ultra-quiet 120mm (140mm on TX750W) double ball-bearing fan delivers excellent airflow
* 80%+ energy efficiency at 20%, 50% and 100% load condition for less heat generation and lower energy bill
* 99% Active Power Factor Correction provides clean and reliable power to your system
* Universal AC input 90~264V automatically scans and detects the correct voltage
* Dedicated single +12V rail offers maximum compatibility with latest components
* Over Current/Voltage/Power Protection, Under Voltage Protection, and Short Circuit Protection provide maximum safety to your critical system components.
* High quality Japanese capacitors provide uncompromised performance and reliability.
* Extra long cables support full tower size chassis.
* TX850W Dimension: 5.9"(W) x 3.4"(H) X 6.3"(L);”
* TX750W Dimension: 5.9"(W) x 3.4"(H) X 6.3"(L);
* TX650W Dimension: 5.9"(W) x 3.4"(H) X 5.9"(L);
* MTBF: 100,000 Hours
* NVIDIA SLI™-ready certified.

At first glance, the TX850 doesn't really look anything overly special, with features such as 80%+ Efficiency, 0.99 Power Factor Correction and an 'ultra-quiet' fan all being things that we've come to expect from any modern PSU. But fear not enthusiasts, the mention of Japanese capacitors and a single +12v rail turns everything around. Obviously, we'll get a chance to take a look inside the unit over the next few pages to see if Corsair have performed any money-saving exercises anywhere else, but for the moment let's take a look at the rail output chart:

AC INPUT1000-240V ~ 12A 50/60Hz
DC OUTPUT+5V+3.3V+12V-12V+5Vsb

Starting off with the single +12v rail, we can see that its 70A (840w) output equates to almost 99% of the unit's total power. This will obviously decrease as load is applied to the +3.3v and +5.0v rails and based on a 10A load on each of these rails, you can expect the +12v output to drop to around 760w. Of course, if the history of Corsair's previous units is anything to go by, there is a chance that the TX850 is capable of delivering a bit more than what is printed on the label, so it will certainly be interesting to see how it performs in the testing over on the next few pages.

Corsair TX850w ATX PSU Page: 2
Packaging & Appearance

Corsair have never been a company to cut corners where the packaging of PSU's is concerned, and as we can see from the images below, the TX series is certainly no exception. Packaged inside a double-walled cardboard box similar in design to that of the HX620, the TX850 is protected by two large styrofoam inserts that completely encompass the unit, protecting it on all sides from damage. Furthermore, Corsair have also gone to the trouble of placing the PSU in a plastic bag along with a black felt bag on top. I'll eat my pants if they've had so much as one unit returned 'damaged in transit'.

Corsair TX 850w Box Corsair TX 850w Box
Contained inside the box is all the usual bits you expect to receive with a new PSU (mains lead, screws, manual) along with a few little extras in the form of some cable ties and a Corsair sticker. The included screws are also painted black, which is certainly a nice change from the usual silver ones.

Corsair TX 850w Box Open Corsair TX 850w Contents
Removing the unit from its elaborate packaging, we are presented with the TX850 in all its glory. Corsair have stuck with the rugged powdercoat finish used on their HX series that feels quite resistant to scratching and almost like the unit is coated in some kind of rock polymer. Yellow and black stickers adorn all sides of unit, giving it a refreshing appearance that helps it stand out in a market filled with drab black boxes.

Corsair TX 850w Underneath Corsair TX 850w Top

Quite unique to the TX850 is the use of a 140mm fan that comes close to touching the edges of the casing and almost looks like Corsair had to use a shoehorn to get it into place. The advantage of such a large fan is primarily to reduce cooling dead spots inside the unit where a traditional 120mm fan cant quite reach, while also shifting more air at lower speeds/noise levels. Interestingly, the TX650 doesn't share the same fans as the 750w and 850w models, quite possibly due to its smaller dimensions and lower output.

Corsair TX 850w Back Corsair TX 850w Specs

Now let's move on to some of the more interesting stuff...the PSU internals...

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Internal Components

Removing the four screws and lifting the lid on the TX850, the first thing that hits you is just how spacious it is inside. Normally, most manufacturers cram components wall to wall, making the casing as small as possible. However, inside the TX there is a good 20mm gap between the PCB and casing on one side, and 5-10mm on the other. Everything inside the unit is tidy, with all cables entering the casing being tightly bunched together and decent space between each of the components allowing them to 'breath'.

Corsair TX 850w Inside Corsair TX 850w Inside

Three black aluminium heatsinks run in parallel across the unit, providing cooling for the attached mosfets. Positioned middle-right we can see the large primary transformer that deals with the +3.3v /+5v and +12v rails, and over to the left of it is yet another transformer, only much smaller, and responsible for dealing with the +5vsb (Standby) rail.
Corsair TX 850w Inside Corsair TX 850w AC Input
The primary capacitor inside the TX850 is a full-height version manufactured by well-regarded Japanese manufacturer Nippon Chemicon. This capacitor has a rating of 450v / 470uF and can do its business all the way up to 105c, indicating that it should stand the test of time inside a toasty PC system. Several other caps can also be seen around the unit, but without de-soldering them, these are much harder to identify. Interestingly, Corsair have also used a single solid polymer capacitor on the 12v side, which generally is a better choice than the standard electrolytic ones, but does seem a little out of place.

Corsair TX 850w Caps/Ferrite/Transformer Corsair TX 850w Capacitor
The 140mm fan is manufactured by a Taiwanese company that many of us - especially watercooling enthusiasts, will have heard of before: Yate Loon. Best known for their high performance 120mm fans with low noise levels, it's certainly no wonder that Corsair insisted on using them inside the TX850. This particular model carries the marking D14BH-12 and a quick check of Yate Loon's website shows that it can push 140CFM at 48.5dBA. Perfect if you intend to run it at lower speeds.
 Corsair TX 850w Fan Corsair TX 8502 Fan
Now that we've finished the tour of the TX850's innards, let's have a quick check at what cables Corsair has fitted it with before moving on to the Pièce de résistance - the load testing.

Cables & Connectors

A total of ten cables extend from the unit branching out into 8xSATA, 8xMolex, 4xPCI-E, 1xATX and 1xEPS connectors. Each and every cable on the unit is sleeved in a black mesh finished off with black heatshrink at the ends. Just like a lot of other units we're reviewed recently, Corsair have decided not to carry the sleeving all the way into the PSU, instead stopping just a couple of centimetres short. This doesn't exactly score points in the looks department, but it does enable each of the nine protruding cables to have a much greater bend radius, which could prove helpful if the PSU were to be installed in a confined space.

Corsair TX 850w Cables Corsair TX 850w Molex Connectors
Each of the four PCI-E cables is capable of being converted to either 6-Pin or 8-Pin standards. This ensures that the TX850 will work with all existing graphics card combinations along with (hopefully) whatever plug and pin combinations that GPU manufacturers enforce on us in the future. 

Similarly, both the 8-Pin EPS-12v and 24-Pin ATX connectors can also be converted back to 20-Pin ATX / 4-Pin P4-12v standards for compatibility with older motherboards if required.

Corsair TX 850w PCI-E Corsair TX 850w ATX + EPS

Next stop - our load testing configuration and the all important results.

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Simulated Load Testing

To provide our readers with the most accurate results, Overclock3D uses a professional grade SunMoon SM-268+ ATE load tester capable of placing a sustained load of 1690w across a total of six rails (including +5vsb and -12v) on the PSU. Unlike our previous resistor-based load tester, the SM-268+ gives us the ability to adjust amperage loads in increments as small as 0.01A while also measuring voltages and wattage readings on-screen.

During today's tests, we will be placing the TX850 under 25%, 50%, 75% and 100% load levels at both room temperature and inside a hot box regulated to a temperature of 45-55°C. Additional cross load tests will also be performed under these conditions to simulate how the PSU would perform with a heavily uneven distribution of load.

Corsair TX850 SM-268+ Results @ Room Temp
  +3.3v +5.0v +12v1 +12v2 +5vSB -12v AC Watts /
 DC Watts
 Efficiency Intake /
 Δ Temp
Test 1
 3.75A 3.75A 14.50A - 0.75A 0.20A 244w /
 87.29% 26.5°C /
 3.34v 5.08v 12.08v - 5.09v -12.16v
Test 2
 7.50A 7.50A 19.00A - 1.5A 0.40A 480w /
 89.37% 26.7°C /
 3.32v 5.06v 12.06v - 5.05v -12.19v
Test 3
 11.25A 11.25A 43.50A - 2.25A 0.60A 721w /
 88.07% 26.3°C /
 3.30v 5.04v 12.04v - 5.00v -12.22v
Test 4
 15.00A 15.00A 58.00A - 3.00A 0.80A 972w /
 87.34% 26.6°C /
 3.27v 5.03v 12.01v - 4.97 -12.25v
Test 5
20.00A20.00A1.00A -0.75A0.20A 207w /
87.92%26.4°C /
 3.25v 5.00v12.07v - 5.09v-11.98v
Test 6
 3.00A 5.00A 68.00A - 0.75A 0.20A 971w /
 87.84% 26.6°C /
 3.29v 5.03v 12.02v - 5.05v -13.80v

Starting off with the room temperature tests, the thing that immediately stands out in all the results is the 89.37% efficiency in Test 2. This is extremely impressive, especially considering the load level is close to what an average 'Gamers' PC is likely to utilise. Even at a low 213w load in Test 1, the unit still manages to give us 87.29% efficiency, lining the unit up for 80 PLUS Silver certification.

Voltage stability results are also extremely good across the board, with all rails staying above or extremely close to their ideal values (3.33v / 5.00v / 12.00v). Even in the gruesome cross load tests, the TX850 manages to keep all voltages fairly balanced and the only slight abnormality is on the -12v rail which shoots up to -13.80v in Test 6.

Interestingly, despite the high efficiency levels, the TX850 does run quite hot under load. In Test 4, the exhaust temperature hits 52.2°C - an increase of 25.6°C over the ambient/intake temperature, and similar results can also be seen in Test 6. In both of these tests, the 140mm fan did spin up significantly to combat the heat, making the unit rather noisy; however, in all other tests the fan remained at a fairly low and almost inaudible level.

Corsair TX850 SM-268+ Results @ 45-55°C
  +3.3v +5.0v +12v1 +12v2 +5vSB -12v AC Watts /
 DC Watts
 Efficiency Intake /
 Δ Temp
Test 1
 3.75A 3.75A 14.50A - 0.75A 0.20A 244w /
 87.29% 47.4°C /
 3.34v 5.08v 12.07v - 5.09v 12.16v
Test 2
 7.50A 7.50A 19.00A - 1.5A 0.40A 485w /
 88.45% 48.9°C /
 3.31v 5.07v 12.05v - 5.05v 12.20v
Test 3
 11.25A 11.25A 43.50A - 2.25A 0.60A 726w /
 87.46% 45.3°C /
 3.29v 5.02v 12.02v - 4.99v 12.24v
Test 4
 15.00A 15.00A 58.00A - 3.00A 0.80A 979w /
 86.72% 46.5°C /
 3.27v 5.00v 11.99v - 4.97v 12.27v
Test 5
20.00A20.00A1.00A -0.75A0.20A 209w /
87.08%53.3°C /
 3.25v 4.98v12.06v - 5.10v11.98v
Test 6
 3.00A 5.00A 68.00A - 0.75A 0.20A 979w /
 87.23% 50.1°C /
 3.30v 5.02v 11.97v - 5.05v 13.9v

Moving on to the hot box testing, which normally separates the men from the boys, we installed the TX850 inside an ATX case fitted with a 300w ceramic heating element, fans to circulate the heat and an industrial temperature controller. The average temperature inside the box is around 50°C, although as our setup is hardly lab grade, a deviation of 5°C in either direction is fairly normal.

The results are pretty amazing in all honesty, with very little difference in efficiency or voltage stability when running with an ambient temperature of up to 53.3°C. The fan inside the unit understandably goes into turbo mode in pretty much all of the tests and even manages to get itself heard above the noisy SM-268+ load tester, but we can forgive it for this considering it's highly unlikely to ever find itself under this kind of stress in a real world scenario.

Corsair TX850w ATX PSU Page: 5

Corsair TX850WThe first words that spring to mind are WOW WOW WOW. The TX850 is really that good. During room temperature testing, the voltage stability was excellent with all rails staying extremely close to their ideal values. Even when placing the unit in some nasty crossloading situations, it just wouldn't flinch and continued to provide rock solid voltages on the most important rails. In an attempt to give the TX850 something to chew on, we loaded the unit all the way up to 920w, but it just gave the TX a chance to prove what a tough cookie it was and  happily carried on delivering perfectly acceptable voltages.

Sticking a PSU in our new 'hot box' warmed all the way up to 50°C is normally more than enough to make any unit cry, but yet again the TX850 pushed out numbers almost identical to the room temperature results, showing that the unit can happily deliver its full 850w load in even the hottest of environments. Efficiency was also close to being the best we've ever seen, with the TX managing over 89% efficiency at medium load levels and no lower than 86% under any other conditions.

Although it's kind of hard to comment on the noise output of the unit when you've got a 1600w load tester whirring away in the background and several high power Delta fans moving air around the hot box, the TX850 certainly seemed to be extremely quiet all the way up to a 700w load. Only when pushed past this point did the fan start to spin up to counteract the heat in our ambient load tests.

As we've come to expect from a Corsair spec'd unit, the TX850 is extremely well-built and uses some of the best internal components. There's very little to dislike about the unit visually either, with its rugged powdercoated finish and sleeved cables. If I was to nit-pick, I would like to have seen the sleeved mesh go all the way into the unit, instead of stopping a couple of millimetres short, but I guess you could argue that it puts form over functionality.

Available from Ebuyer for £111.64 the TX850 comes in at a competitive price point, and in my opinion at least - is worth every penny.

The Good
- Extremely stable rails even at full load @ 50c.
- Efficiency bordering on 90% at medium loads.
- Great looks.
- Plenty of cables & support for all hardware.
- Performed really well in our cross load tests.
- High quality internal components.

The Mediocre
- The -12v rail does get a bit high on a heavy cross load, but this is extremely unlikely to occur in a normal PC.
- Makes a bit of a racket at 850w load.
- Corsair need to make a modular version for all us neat freaks :)

The Bad
- Absolutely nothing.

Overclock3D Editors Choice

Thanks to Corsair for sending the TX850W in for review. Discuss this review in our forums.