ASUS U-75HA 750w ATX PSU Page: 1
Indisputably one of the largest manufacturers in the PC enthusiast industry, ASUS is a name that almost everyone will recognise for their wide range of motherboards, graphics cards, CPU coolers and innovations such as the affordable EeePC netbook. However, while ASUS' exploration into new markets has never really come as much of a surprise to us here at Overclock3D, when we recently got wind that they were planning on releasing their own range of PSU's our jaws literally hit the floor.
But why the reaction? Well, over the past few years there has been an undeniable increase in companies that have absolutely no previous experience in the PSU market jumping on the bandwagon. This has resulted in the market being flooded with PSU's, most of which are made in the same factories and all are fighting for a place on retailers shelves. Of course this isn't necessarily bad for the consumer as more competition often results in price wars and many bargains to be had, but from the side of the manufacturer such competition in an extremely crowded market can be crippling.
Of course, maybe I'm jumping the gun here. After all both OCZ and Corsair went from little more than a memory manufacturers to being some of the most preferred PSU manufacturers (in the UK at least) overnight. It's totally possible that a large name such as ASUS could do exactly the same. So with an open mind, let's take a look at the specifications listed on ASUS' website:
Equipped with four +12V rails, the U-75HA provides enhanced stability. Additionally, the U-75HA is certified with the 80 PLUS specification for great energy efficiency.
Certified with 80 PLUS specification (up to 86% efficiency)
Active PFC delivers environmentally friendly power with a high power factor (PF) of up to 99%
Accurate power rating delivers its full rated power
ATX12V Ver. 2.3 compliant-real four 12V rails provide stable support for high-end graphic cards
Dedicated power circuitry: delivers reliable output to delicate components
13.5 cm ball-bearing fan with auto thermal acoustics noise control
Cable sleeve improves internal airflow within the system.
Hexagon venting holes for efficient heat dissipation
Provides both 6-pin and 8-pin PCI-Express connectors for future upgrade to graphic cards
Rich expandability with 6 SATA, 6 peripherals, 2 FDD, 4 PCI-E and 1 EPS connectors
EPS connector provided for dual CPU usage
Certified with CUS, Nemko, CE, BSMI, TUV, FCC, C-TICK
Protection: OVP, SCP, OCP, NLO, OTP, UVP, OPP
Input Voltage Range
Input Frequency Range
Starting with the basics, the U-75HA is certified as an 80Plus efficiency unit with ASUS claiming levels as high as 86%. Under the new 80Plus rating system this effectively certifies the unit as an 80Plus Bronze PSU, with Silver certification just 2% out of its reach (providing the unit can deliver its 86% efficiency at 50% load).
As the specification table above shows, the U-75HA features four +12v rails rated at 18a each with a maximum load of 648w (54a). This realistically brings the maximum output of each rail down to 13.5a if each rail were to be equally loaded at the same time (as we will be doing during the testing). Interestingly the ASUS website calls these rails "real four 12V rails" which by our definition is highly unlikely as it would require four separate 12v transformers. More realistically the U-75HA has one 12v transformer that is 'virtually' split into four with over current protection kicking in at 18a on each of the' virtual' rails.
The other main rails: +3.3v and +5v are both rated at 30a each with a maximum load across both rails of 160w. Although the technique for calculating the amperage output of each rail is not quite as simple as the +12v rails as there are two different voltages to contend with (+3.3v & +5v) , heavily loading the PSU in either direction still leaves a reasonable amount of power for the other rail.
Now let's move on to the unboxing of the U-75HA and its external appearance.
ASUS U-75HA 750w ATX PSU Page: 2
Packaging & Appearance
When it comes to the packaging of products such as motherboards and graphics cards, ASUS are well known for their elaborately large boxes often printed with tasteful graphics and extravagant accessory bundles. However, for the U-75HA things are a little more down-to-earth with a rather average sized box that has no hidden flaps or windowed panels and a fairly basic, yet professional looking blue, green and white colour scheme.
Unfortunately, ASUS seems to have taken things a little too far in the cost saving category, with the PSU being described in large white writing as "750w / 650w". Well what is it, 750w or 650w? It's not until you view the side of the box where ASUS have placed a small circular sticker over the 750w tickbox that you actually have any idea of what you might be purchasing.
Moving round to the back of the box we can see that ASUS have printed a specifications table similar to that seen on page one of our review. Also included are the specs of the 650w model which has slightly lower output across all of its rails in comparison to the 750w model. A general specification header also provides a short list of features common to both models.
To protect the PSU during shipping ASUS has sandwiched the U-75HA between two cardboard backed styrofoam inserts and placed it in a clear plastic bag. This, combined with the additional protection from the cable bundle and accessories box should ensure that the the unit reaches you in perfect condition even at the hands of a particularly rough courier. Also included in the box is a mains cable, bag of screws and some ASUS branded velcro strips.
Removing the unit from it's packaging we can see that ASUS have gone for a fairly standard design. The finish on the unit is a powdercoat paint in a slightly off-black colour that feels quite rugged. At the rear of the unit is a honeycomb mesh along with a rather large power switch that gives a really reassuring click compared to the tiny electronics project ones you see used by a lot of manufacturers. At the top - or bottom- of the unit (depending on what kind of PC case you have) is a large 135mm fan covered with a gold wire fan grill sporting the Vento logo. It is worth noting that the 650w model only features a 120mm fan and as such, will look slightly different to the 750w model.
Moving round to the side of the unit we come to the obligatory specification sticker. As per usual, this sticker provides a rail output table along with the usual warning about how you will meet your shocking demise should you open the PSU cover. Aside from the sticker there really is very little else to talk about in all honesty. No vents, embossed ASUS logo's or other custom designs. Just a plain Jane black box.
Lets move on now and take a look inside the belly of the beast...
ASUS U-75HA 750w ATX PSU Page: 3
Truth be told, there are very few 'manufacturers' out there who actually make their own PSU's. This is mainly because PSU manufacture isn't something that you can get good at over night, and the tools and machinery that go into producing a PSU would be a totally uneconomical investment for even a company as large as ASUS. For this reason, ASUS along with many other well know PSU brands use what is known as an OEM (Original Equipment Manufacturer) to build their PSU's for them.
However, this certainly doesn't mean that ASUS hasn't been involved in the specification and design of the unit. Far from it. Aside from selecting the actual OEM to build the units there are many other ways in which ASUS can make their PSU different from the generic ones that the OEM may build. This starts with things like how many cables are going to be included, what colour sleeving (if any) is it going to have, how much power is going to go to each of the PSU's rails and what kind of fan is going to be used..the list is really endless.
Therefore, even though we know that ASUS have chosen DELTA as their OEM, there's still plenty of reasons to poke around inside the unit and find out just what makes it tick!
Starting off with the basics, the internal layout of the U-75HA is quite tidy with all cables neatly zip-tied together to keep them well out the way of fan blades. Two black aluminium heatsinks attached to the mosfets span the length of the unit, and finned areas of the heatsink increase the surface area making better use of the 135mm fan that would normally be positioned directly above.
Going in for a closer look we can see that the U-75HA features two 450v, 85c capacitors manufactured by Taiwanese company CapXon. Although we could argue that opting for 105c capacitors would help to increase the MTBF of the unit, CapXon are by no means a cheap brand and should definitely stand the test of time.
In the image top-right we can see the three main transformers of the PSU that perform the brunt of the voltage step-down to what is used inside the average PC. While the largest of the three is undoubtedly responsible for the 12v rails and the mid-sized one for the 5v and 3.3v rails, we're not entirely sure what role the smallest one plays.
Finally we come to the 135x135x25mm manufactured by ADDA with a model number of ADN512UB-A9. Unfortunately even after a thorough search of Google and ADDA's website we was unable to dig up any airflow or noise output figures for this fan. All we can tell you is that it's black, has nine impeller blades, runs at 12v and consumes 0.44a...great!
The U-75HA has a total of nine cables extending from the unit that branch out into 6xSATA, 6xMolex, 4xPCI-E, 1xATX, 1xEPS and 1xP4-12v connectors. This is about average for a PSU of this wattage although both the PCP&C Silencer 750w and the Be-Quiet Dark Power Pro 650w beat it by at least two additional connectors.
Each and every cable on the unit is sleeved in a black mesh finished off black heatshrink at the ends. Interestingly ASUS have decided not to carry the sleeving right the way into the PSU, instead stopping just a couple of centimetres short. Admittedly this doesn't exactly do much for the looks of the unit, 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.
'Easy-plug' connectors have also been used on each of the six molex plugs to make removal from devices much easier.
Rather than having four PCI-E cables extending from the PSU for each of the four PCI-E plugs, ASUS have decided to 'piggy-back' two plugs off a single main cable. This reduces cable clutter when running Crossfire/SLI with high-powered graphics cards but does mean that if you only have a single card with a single PCI-E connector, you'll be left with a flappy bit of wire to try and tuck away. All four of the PCI-E connectors are capable of being converted into either 6-Pin or 8-Pin to suit all graphics cards.
The ATX cable is native 24-pin with no way of reducing it down to the older 20-Pin standard (unless you are handy with a junior hack-saw?). In all honesty this shouldn't be an issue as almost all modern motherboards use the 24-Pin ATX headers anyway. Additionally a lot of the 20+4 Pin ATX connectors are a right pain in the rear to 'couple-up' before inserting them into your motherboard - anybody who's ever tried it will probably understand what I mean!
Legacy connectors haven't been completely ditched however, with the unit providing a separate cable for low-end motherboards (mostly mATX) that still use the 4-Pin 'P4-12v' connector.
ASUS U-75HA 750w ATX PSU Page: 4
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 todays tests we will be placing the U-75HA under 25%, 50%, 75% and 100% load levels and taking voltage readings at every stage. The chart below details the exact amperage load placed on each rail of the PSU at the aforementioned load levels:
| || 25%|| 50%|| 75%|| 100%|
| +3.3v|| 6.06A|| 12.12A|| 18.18A|| 20.0A|
| +5.0v|| 5.00A|| 10.00A|| 15.00A|| 17.50A|
| +12v1 / +12v2 * || 6.75A|| 13.50A|| 20.25A|| 25.00A|
| +12v3 / +12v4 * || 6.75A|| 13.50A|| 20.25A|| 25.00A|
| +5vsb|| 0.875A|| 1.750A|| 2.625A|| 3.50A|
| -12v|| 0.175A|| 0.350A|| 0.525A|| 0.60A|
| Total **|| 215.8W|| 429.0W|| 641.8W|| 764.0W|
* Rails 1&2 and 3&4 on the U-75HA have been combined during testing on the SM-268+ due to a limitation with the testing equipment. However, as the U-75HA features only one +12v transformer this becomes irrelevant as we are effectively re-joining virtually split rails.
** Total wattage is taken directly from the SM-268+ readout rather than a calculation of the amperage loads.
Now that we've seen exactly what load we're placing on the U-75HA let's see how it performed...
| || 25%|| 50%|| 75%|| 100%|
| +3.3v|| 3.30v|| 3.26v|| 3.22v|| 3.14v|
| +5.0v|| 5.04v|| 5.01v|| 4.97v|| 4.89v|
| +12v1 / +12v2 || 12.16v|| 12.12v|| 12.08v|| 11.89v|
| +12v3 / +12v4 || 12.15v|| 12.11v|| 12.07v|| 11.70v|
| +5vsb|| 5.06v|| 5.01v|| 4.96v|| 4.85v|
| -12v|| -12.08v|| -12.14v|| -12.19v|| -12.28v|
At 25% and 50% loads we get a chance to see the voltage output of the rails close to what they have been set at in the factory. Unlike some less reputable manufacturers, ASUS has chosen not to over-volt the rails in an attempt to keep voltage readings looking good when a heavy load is applied. Both the +3.3v, +5.0v and +12v rails sit comfortably within 2% of their ideal voltages.
Moving on to 75% load the voltages take a small dip, but aside from the slightly low 3.22v output from the +3.3v rail there's nothing much to worry about.
Finally at 100% load everything goes down hill with +3.3v rail coming extremely close to falling outside the ATX +/-5% requirement. The +12v3/4 rails also take quite a dip down to 11.70v which is still within ATX spec but would have most hardcore enthusiasts running for the hills. All other rails remain reasonable, but the performance certainly isn't anything to shout about.
Efficiency tests are performed by measuring the wattage consumed by the power supply at the mains (Mains Draw) against the wattage readout displayed on the SM-268+ load tester (PSU Load). These results should offer around 99% accuracy placing them extremely close to results obtained from professional equipment.
| || 25%|| 50%|| 75%|| 100%|
| Mains Draw|| 256w|| 499w|| 752w|| 917w|
| PSU Load|| 215.8w|| 429w|| 641.8w|| 764w|
| 84.29%|| 85.97%|| 85.34%|| 83.31%|
ASUS claim that the U-75HA is capable of up to 86% efficiency and judging by the results we obtained this is certainly very close to the truth. At 50% load the U-75HA was drawing a total of 499w from the wall socket and the SM-268+ load tester was reporting a load of 429w. By taking both of these figures and applying some simple math (Load / Draw * 100) we arrive at a result of 85.97% efficiency.
Considering that most mid-range PC systems with single high-end graphics cards will consume somewhere in the region of 450w its good to see that this is where the ASUS delivers its best results.
As with all components in the modern computer system, the performance of a PSU can be directly affected by heat. Excess levels of heat recorded at the PSU's exhaust can indicate that the cooling system is inadequate in keeping the PSU's internal temperature under control which can subsequently lead to a reduction in the maximum power output of the unit. For this reason Overclock3D takes temperature readings from the PSU's intake and exhaust areas after 10 minutes of running at each specified load level. These results can be seen below.
| || 25%|| 50%|| 75%|| 100%|
| Intake|| 19.9°C|| 19.6°C|| 20.1°C|| 19.7°C|
| Exhaust|| 22.4°C|| 24.9°C|| 26.3°C|| 29.3°C|
| 2.5°C|| 4.9°C|| 6.2°C|| 9.6°C|
With a maximum exhaust temperature of 29.3°C when under 100% load, the U-75HA certainly doesn't show any signs of overheating. This is undoubtedly down to the high efficiency of the unit (less energy being wasted as heat) and the 135mm fan. Even at 100% load, the U-75HA hardly increased the fan speed to combat the additional heat and as a result the unit remained fairly quiet. While we would like to make an official comment on the noise output of the unit, the SM-268+ load tester is far too noisy and prevents any measurements - subjective or scientific from being taken.
In our continuing efforts to increase the quality and accuracy of reviews here on Overclock3D we recently invested in professional PSU load testing equipment. However, while this allows us to place accurate load levels on a PSU during testing there are still several areas for improvement that you will see from us in the near future:
• Heat chamber testing. All PSU testing will be conducted at a standard temperature of 50c.
• Digital Oscilloscope. For measurement of ripple and line noise.
• Variable AC Transformer. For conducting PSU reviews at both 240VAC and 120VAC mains voltages
• Digital Tachometer. To observe fan speed as temperature and load increase.
• Noise Recordings. Allow readers to experience the noise emitted from the PSU for themselves.
Providing we still have access to the ASUS U-75HA once our updated testing suite is in place we will be sure to update this page of the review with the additional results.
ASUS U-75HA 750w ATX PSU Page: 5
As ASUS' first entry into the PSU market we had high hopes that they was going to bring something new and unique to the table. After all, ASUS is a name that most enthusiasts will associate with high-end radically designed motherboards with extreme performance and more gadgets than you can shake a stick at. Unfortunately ASUS let us down.
While the U-75HA is certainly not a bad PSU by any means, it's hard to describe it as anything more than 'average' - a proverbial plain Jane of the PSU world. It almost feels like ASUS went shopping one day, picked a PSU from the shelf and decided to re-brand it as their own. There really is no 'ASUS' as we know it in the U-75HA, no sign that anybody has actually given any though to how the age-old PSU design used by so many manufacturers could be improved upon, and unfortunately as a result the U-75HA is likely to find it very hard to gain a foothold in an already saturated market.
However, while the U-75HA may not quite have lived up to our expectations it certainly doesn't mean that the power supply should be shunned by those of us who are looking for a no nonsense 750w unit that simply gets the job done. Load voltages were good all the way up to 75% and efficiency came within a whisker of 86% when under 429w load. Only when we pressed it to it's limits did the U-75HA show signs of strain with the +3.3v rail dropping to 3.1v and the +12v3/4 rails dipping 11.70v. While we couldn't get any official noise measurements for the unit due to the noise emitted from our SM-268+ load tester, the U-75HA remained cool throughout the tests and as a result only needed to increase the fan speed slightly.
At present there are no stores in the UK listing the U-75HA; making it impossible to work out where ASUS have positioned the U-75HA price-wise in the market. However, when this information becomes available to us the scoring chart below will be updated.
- Cool running even at 100% load.
- Up to 86% efficiency.
- Reasonable stability up to 75% load.
- 3.3v rail falls outside of ATX spec at 100% load.
- Nothing to separate the U-75HA from any other standard PSU on the market.
Thanks to ASUS for providing the U-75HA for review. Discuss this review in our forums.