FSP Aurum Power Supply Unit Series: in Chase of Gold

FSP Company, which has fallen a little behind competition in the PSU field lately, decided to catch up in one powerful dash and introduced an entire new series of power supply units built on a completely new platform.

by Oleg Artamonov
08/04/2011 | 04:28 PM

Gold is highly popular among power supply makers. On one hand, the precious metal has been attracting people for centuries and, on the other hand, every PSU maker deems it a matter of personal pride to reach the highest grade of the 80+PLUS certification which has been split up into Bronze, Silver and Gold categories.


So, we’ve got such products as Seasonic X Gold (reviewed already and soon to be reexamined in our labs) or Cooler Master Pro Gold (it will hopefully reach us soon). In the name of the product I am going to review today the English word is just replaced with its Latin equivalent Aurum. Of course, there are a lot of references to gold on the product packaging and in the promotional materials. After all, some users may just not know Latin or the chemical element Au.

Well, my job is not to refresh your school chemistry course but to test new power supplies from FSP. So, let’s get started.

Testing Methodology

Click the following link for a description of our testing methodology and equipment and a brief explanation of what the specified and tested parameters of power supplies mean: X-bit Labs Presents: Power Supply Units Testing Methodology. If you feel overwhelmed with the numbers and terms this review abounds in, refer to the Methodology.

You can also go to our Cases/PSU section to check out reviews of all other PSU models we have tested in our labs.

We will mark the actual power consumption of three system configurations (discussed in our article PC Power Consumption: How Many Watts Do We Need?) in the cross-load diagrams. This will help you see if the tested PSU can meet the requirements of a real-life PC.

FSP Aurum AU-700

The Aurum family is split in two subseries depending on whether the PSU has detachable or fixed cables. The Aurum products with fixed cables range from a 400W model to this 700W one.

The PSU comes in a nice-looking gold-and-black box. FSP prints a special wrapper for each model, so the wattage rating and product name can be found all over the packaging rather than on a sticker somewhere in a corner.

The product’s numerous advantages are detailed on the back of the box. Besides enumerating the PSU’s connectors, the length of each cable is also indicated, which may be important for many users.

Here are the advantages listed on the box:

The accessories are rather scanty.

We've got the following things here: an installation guide in multiple languages, four screws, three cable straps, a Power by FSP sticker, and a power cable. Well, what else could they have put with a PSU?

The PSU itself is even prettier than its packaging. It’s got a black case with a rough surface, a number of vent grids, including the Arrow Flow grid in the side panel, and a beige (this must be meant to be golden) plastic piece on the fan.

The back panel is blank except for the dozen vent grids shaped as arrows. Take note of the consistency of design: the plastic rim of the opening for cables follows the overall style with its angular shape and beige color.

The interior of the PSU makes it clear that it has nothing in common with the popular Epsilon series.

It’s quite roomy inside. The medium-sized black heatsink decorates the power components of the PFC device and main transformer whereas the tiny silvery one (higher in the photo) cools the transistors of the +12V synchronous rectifier. Well, I do believe in the efficiency of over 90% after seeing such heatsinks.

Every chip in this PSU is marked as "FSP", so the "chipset" can indeed be viewed as FSP's original. As far as I know, FSP not just rebrands a standard controller but changes something in its circuitry, putting some of the elements that are usually installed outside into the controller chip. Producing such custom-made chips is justified by FSP's large production volumes. The expense of ordering them is covered by the lower manufacturing price of resulting PSUs (thanks to the transfer of some components into the chip) and also by the inability of the mainland China competitors to copy the circuit and produce cheap clones. Knowing the PSU circuit design is useless unless you have FSP chips. This is an insurmountable obstacle to typical Chinese factories that do not have experienced engineers capable of adapting a PSU circuit to their manufacturing capabilities, let alone developing a new circuit from scratch.

The emptiness of the PCB when viewed from above is made up for by the bottom view: most of the smaller components (resistors, low-rating capacitors, low-power diodes and transistors, optocouplers, etc) are simply surface-mounted and populate densely the bottom of the PCB.

We can also see some of the power transistors of the output circuitry here. I mean the four rather large squares of the field transistors in the bottom right. Thanks to their high efficiency and low heat dissipation they don't need a heatsink but can be cooled well enough through the PCB interconnects they are soldered to. The same can be seen in the Seasonic X series as well as some other products with DC-DC converters at the output.

The quality of soldering is immaculate. The top right corner (as viewed in the photograph) with wires from the mains connector is somewhat smudged with soldering flux, but that’s not a problem at all. Every surface-mounted element is secured with glue as is typical of PCBs with dual-sided mounting that are assembled in three steps. First, the bottom-surface components are glued to the PCB, then the PCB is turned upside down and gets its top-surface components, and then it goes into the machine for wave soldering. Without the glue the process would be more difficult. The components would have to be soldered in two passes with such methods that the components on the bottom side of the PCB didn’t fall off.

Although we’ve read about Japan-made capacitors on the product packaging, the PSU proves to have mostly Taiwan-made ones. It is the KF series from CapXon. I wouldn’t call them bad, yet I wouldn’t call them Japanese, either. Well, on a second thought, the packaging mentions a Japanese capacitor in the singular and you can indeed find one in the PSU. It is the high-voltage thing standing next to the PFC device. By the way, it is the capacitor that has got special protection according to the same text on the box.

The PSU is cooled by a Protechnic Electric MGA12012HF-A25 fan that has a fluid dynamic bearing and a rated speed of 2400 RPM. The fan looks pretty with its rounded-off shapes but the noisiness of the PSU is going to depend on speed regulation since the max speed is quite high.

The PSU is equipped with the following cables and connectors:

We've got a sufficient selection of connectors here, especially as the CPU cable is as long as 70 centimeters (from the PSU case to the connector on its end) and you can easily connect it in a full-tower system case with a bottom PSU bay and a hidden compartment for cables. Unfortunately, some makers still produce PSUs with a CPU cable of only 55 to 60 centimeters long, which may be insufficient. Take note that the Aurum series models with a wattage rating below 700 watts do not have the second connector on the CPU cable, so the latter is only 55 centimeters long with them.

Every cable has a nylon sleeve.

The manufacturer says that the PSU has four “virtual” +12V output lines, each for a max current of 18 amperes. Indeed, the individual +12V outputs are connected on the PCB via current-measuring shunts. However, I could not overload any single line during my tests. For example, the CPU power line (12V2) worked normally at a load of 35 amperes irrespective of whether the load would increase from 0 to 35 amperes smoothly or instantaneously. So, the PSU seems to be protected against overload on the +12V lines combined, but not against overload on the individual lines.

Working with my UPS (APC SmartUPS SC 620 with non-sinusoidal output voltage), the power supply was stable at loads up to 395 W (when powered by the mains) and 350 W (when powered by the UPS’s batteries). This, the FSP Aurum shouldn’t have compatibility issues with uninterruptible power supplies.

We can see some red in the cross-load diagram but none of the voltages goes out of the permissible limits (5% from its nominal level) at any load. Moreover, the PSU is stable at near-zero as well as greatly misbalanced loads (for example, when there is a load of over 650 watts on the +12V rail and no load at all on the +5V and +3.3V rails). Thus, the FSP Aurum is going to be compatible with any PC configuration, including low-power-consumption ones (of course, using a 700W power supply for an Intel Atom machine wouldn't make any point, but we shouldn't forget that even top-end computers may have a very low power draw when idle).

The high-frequency output voltage ripple is quite conspicuous at full load, but its level is within the permissible limits.

The low-frequency voltage ripple (at the double frequency of the mains, i.e. 100 Hz in my location) could be observed on the +3.3V rail but never went beyond the permissible limit, either.

The PSU is almost 93% efficient at the peak and 90% efficient at full load. Even at a load of 50 watts (which is about one fifteenth of its full output power) the efficiency is but slightly lower than 80%. That's an excellent result.

It’s worse with noise. The fan rotates at about 800 RPM right after you turn the PSU on but accelerates to 1300 RPM in a few minutes even at a load of only 50 watts. However good a 120mm fan may be (and the PSU’s fan seems to be better than the older Protechnic Electric fans installed into the FSP Epsilon series), it cannot be silent at such a high speed. The hiss of the air is perfectly audible.

To make things even worse, the fan speed grows up linearly at higher loads (i.e. as the PSU gets hotter), reaching a maximum of 2230 RPM at only about 500 watts.

Thus, the FSP Aurum is below average in terms of noisiness. When it comes to acoustic comfort, it is no competitor not only to the quiet PSUs from Seasonic, Enermax and Enhance but even to the ordinary products from Channel Well Technology that sell under different brands (including Thermaltake, for example).

It is unclear what prevented FSP from implementing in this otherwise carefully designed and thought-through product the conventional algorithm of fan regulation: a constant low speed at 50% and lower loads and a linear growth of speed afterwards.

This algorithm is most logical. On one hand, there is a minimum voltage at which any sample of the fan is guaranteed to work. Let's suppose it is 5 volts. A fan with a rated speed of 2400 RPM will be rotating at 2400 / (12/5) = 1000 RPM if supplied this 5-volt voltage. However, working at 1000 RPM, the fan is quite capable of cooling the PSU at loads up to 450 watts, for example. We can’t supply a lower voltage at a lower load because we can’t be sure the fan will start up at all then. So, we can use a 4-pin fan with a larger guaranteed speed range or supply 5 volts to start the fan up at minimum load and keep this voltage until a PSU load of 450 watts. The second solution is implemented by almost all of the PSU makers as it allows to easily produce a PSU that will be rather quiet at low and medium loads and will not overheat at high loads.

It is unclear why FSP doesn’t use this algorithm but implements the outdated linear regulation method in its new product series. With the linear regulation, the minimum of speed is still determined by the minimum voltage of the fan, but the fan accelerates as soon as the PSU load increases although that's not really necessary. As you can see in the diagram, the PSU remains cold: at a load of 500 watts the difference in the temperature of the air going in and out the PSU is no larger than 3°C.

So, whatever the reason for that, the FSP Aurum is a noisy power supply.

The test of the standby source doesn’t produce any surprises. The device easily copes with the specified load of 3.5 amperes.

FSP Aurum CM AU-650M and AU-750M

I will review the two next PSUs together since they are similar and belong to the senior branch of the Aurum family that ranges from 550 to 750 watts.

The box is not much different from the packaging of the ordinary Aurum in design but larger. The main difference of the Aurum CM line from the Aurum is mentioned on the box. It is Cable Management or detachable cables.

The various advantages of the product are again listed on the back of the box. They range from indisputable (like the efficiency of over 90%) to dubious (like the intricately shaped vent grid) and downright incomprehensible (Hybrid Synergy 12V Rail Design; as I’ve found out, the Aurum has formal separation of the 12V power rail into multiple output lines but it never shows up in practice). All of this has been discussed above in my description of the AU-700 model. I can see only two differences so far. The Aurum CM units have detachable cables which are also flat. You'll see shortly what I mean by that.

Besides the PSU proper, the box contains a power cord, a user guide, screws, a cable strap, and a sticker for your system case.

The Aurum CM series looks the same as the Aurum except that the case is somewhat longer. The exterior design is beautiful: a black case with a rough surface, a golden decorative piece above the fan, an originally shaped fan grid, and the arrows of the vent grid in the side panel. I'd replace the arrows with something less beautiful but more transparent for the air, though.

The connectors for detachable cables can be found on the back panel. You can’t connect anything wrong because they differ in shape.

Inside, we can see the same circuit design with almost the same components as in the ordinary Aurum. The only notable difference is the second PCB with connectors at the back panel. It is to accommodate the additional PCB, which doesn’t carry anything besides the connectors, that the case has been made longer.

This is a modern PSU whose high efficiency helps it do with small heatsinks. There are a lot of surface-mounted components on the reverse side of the PCB, so its top side looks kind of empty, carrying but large components that cannot be surface-mounted.

The PSU employs FSP-branded chips which, as I explained above, are not simply rebranded chips from some other maker. The reasons for producing such custom-made chips show up when they are ordered in large quantities, but I have no doubt that FSP produces power supplies in large batches.

Take note of the marks to the left and above the chip. They indicate that this platform is meant for wattage ratings of 350 to 800 watts. So, we can expect the Aurum series to be extended both ways. Or there may appear inexpensive low-wattage PSUs under other names but based on this platform.

As opposed to the Aurum, the Aurum CM really uses Japan-made capacitors, the KZE series from United Chemi-Con. This fact will hardly affect the operation of the PSU, though.

The PSU is cooled with the same 120mm 2400RPM Protechnic Electric MGA12012HF-A25 fan running on a fluid dynamic bearing.

The PSU is equipped with the following cables and connectors:

Included with the PSU are:

There is nothing I can find fault with except that the CPU cable shouldn’t have been shortened to 55 centimeters but left as long as 65-70 centimeters in the models with wattage ratings below 700 watts. The 55cm CPU cable may prove to be too short in most system cases with a bottom PSU compartment unless you use adapters and extenders.

The fixed cables have nylon sleeves. The detachable ones are decorated more originally:

They are flat and have a casing that resembles heat-shrink tubing but is much more flexible. As a result, the cables are compact, flexible and can be easily laid out anywhere in the system case.

Each of these two models has four “virtual” +12V lines but this never shows up in practice. Each behaves as if it has a single +12V power rail and doesn’t shut down when one of the +12V output lines gets overloaded.

Working with my APC SmartUPS SC 620 (non-sinusoidal output voltage), the 650W Aurum CM was stable at loads up to 404 watts (when powered by the mains) and 340 watts (when powered by the batteries). These numbers were 390 and 350 watts, respectively, for the 750W model. The PSU and UPS pair was blameless until these loads but the UPS would shut down, reporting overload, as soon as the load got higher.

The 650W unit is let down by the +5V rail whose voltage sags below the permissible level of 4.75 volts at high loads. On the other hand, no modern computer can produce such loads (it is the +12V rail that has the highest load whereas the 5V rail accounts for but 30-40 watts), so I don't find any critical problems with the AU-650M.

The AU-750M is somewhat worse. Besides the +5V voltage sagging at high loads, its +12V voltage goes below the permissible minimum when there is a high load on the +12V rail (over 600 watts) and a low load on the +5V and +3.3V rails (less than 40 watts combined). I don't think that such greatly misbalanced loads can be found in a real-life computer, yet most other PSUs cope with them. So, although this is no critical problem, it is a downside nonetheless.

The high-frequency output voltage ripple is quite conspicuous at full load but its level is within the permissible limits.

The same goes for the low-frequency ripple.

The PSUs are both highly efficient: over 92% at the peak and no less than 89% at full load.

Unfortunately, the fan regulation of the Aurum CM units is the same as in the Aurum. When the PSU is turned on, its fan starts out at 800 RPM but quickly accelerates to 1200-1300 RPM even at low loads. After that, its speed grows up linearly along with the load (i.e. the temperature inside the PSU) until it hits the maximum of 2230 RPM.

Thus, the FSP Aurum and Aurum CM power supplies are only average in terms of noisiness. They are not quiet, let alone silent, even at low loads (like 50 watts), so they can only be recommended for office use or for people who don’t care much about how much noise their home computer makes. In fact, nearly all of the competing products from other brands are superior to the Aurum series in terms of acoustic comfort at loads up to 500 watts and many of them are better at higher loads, too.

The standby source is stable and delivers its promised 3.5 amperes. As a matter of fact, I can’t remember more than three PSU models priced higher than $30 that couldn’t pass this test.


I must admit that FSP’s Aurum and Aurum CM power supplies made a very diverse impression on me. On one hand, the engineers, designers and marketing people from FSP Group have obviously worked hard on these products. These PSUs are neat, beautiful, and overall immaculate from an aesthetic point of view. They are based on a new platform that features good technical parameters at large and excellent efficiency in particular. If I were to select a power supply based on its looks, the Aurum series would surely be among my favorites.

On the other hand, they have poor fan speed regulation which makes them too noisy. Linear regulation has been proved ineffective, so most manufacturers prefer to implement dual-zone regulation even in inexpensive products (when the fan works at a constant low speed up to a certain point and accelerates in a linear manner thereafter). Some manufacturers, for example Seasonic in the X series, add a third zone in which the fan doesn’t rotate at all. It’s really a mystery to me why FSP implemented linear regulation in their completely new products, thus killing one of the most important consumer properties of an expensive PSU.

I only hope that FSP will soon release an updated series, like Aurum+, with better fan regulation, and we will defintiely follow up with a new review at that point.