Fortron-Source Power Blue Storm AX500-A PSU

Table of Contents

Fortron-Source is the source for many power supplies in the PC marketplace, not just under their own brand but many others and as OEM gear. Blues Storm is definitely one of their own line, a new one that features many modern features and performance — including one of the flattest power efficiency curves we’ve seen on any PSU tested. We take this out this new 120mm fan PSU out for a few tests.

January 14, 2005 by Devon Cooke with Mike

Source Power Blue Storm AX500-A

460W ATX/BTX power supply
Source Power

Market Price


The FSP Blue Storm AX500-A is designed in-house by a major producer of
power supplies: Fortron, who happen to make many of the PSU sold under other brands as quiet products. They are also active in the OEM business. We have reviewed one other Fortron power supply before; the
was the first 120mm PSU that we reviewed, nearly a year and a half ago. That power
supply was OK for noise but otherwise unremarkable. The Blue Storm is aimed at higher end market.

The PSU casing is a deep metallic blue, and the fan is a matching colour.
Even the power switch on the back glows blue when it is flipped on. It is easy
to see where it got the “blue” in its name. However, we are more interested
in the “storm” part of the name, which leads to a central question
of this review: Is it quiet?

A standard retail box with all the necessities but no extras: PSU, power cable,
mounting screws, 20-24 pin adaptor, and an instruction manual.

The Blue Storm is very… blue. The blue mesh sleeving on the cables
is helpful for cable management.

The blueness continues: The fan, power switch and Molex connectors are
all blue.


Latest ATX12V v2.0 with backwards compatibility Supports most
BSCC (Blue Storm Cooling Control) with optimized structure for
whisper-quiet operation
It has a
fan controller.
Environmentally friendly with the incorporation of PFC Passive.
12V rails
for CPU and peripherals, in accordance to TUV safety
An increasingly
common feature, required in ATX12V v2.0
Mesh sleeving on all output cables For ease in
cable management. And… they’re blue!
Flexi Connect
with: 6 x Smart Housing Molex connectors
Easy-off grips for
the Molex connectors. A welcome feature.
CE, TUV EN60950,/ UL60950, CSA, NEMKO
the more the better.


AC Input

115Vrms±10% or 230Vrms±10% at 47-63Hz

DC Output







Maximum Output Current







Maximum Combined







This table is compiled from this
on the Fortron-Source USA website.
The maximum wattages for the +12V lines, the -12V line and the +5VSB line
have been extrapolated from the rather sketchy information in this document.
Note that even though this unit is sold as a 500W unit it is only rated
for 461W. This discrepancy is apparent when comparing the rating on the
box (500W) to the rating on the unit itself, which is correctly labelled
at 460W.

In practical use, this discrepancy will have little effect; building
a system that draws 460W is almost unimaginable. The extra 40W of headroom
is unlikely to be missed in any real-world application. Still, selling
this power supply as a 500W unit is very misleading; it contradicts Fortron’s own specifications.


There are two notable features on the Blue Storm. One is a power switch that
glows blue when it is turned on. Anybody who has ever fumbled around for the
switch in the dark behind their case should appreciate this feature. Unfortunately,
because the switch is only illuminated when it is turned on, fumbling for
the switch while it is off is still an issue. It is likely that this feature
was included more for cosmetic reasons than convenience in the dark. Still,
it is nice to have a visual cue that shows whether there is external current
flowing into the unit.

The second feature is the inclusion of “Smart Housing Molex Connectors”.
These seem to be identical to the Molex connectors with grips on the Cooler
Master RS-450-ACLY that we recently
. This is not a bad thing; Molex connectors have needed an
ergonomic upgrade for a long time. This feature should be on all power supplies.

A tightly packed case .

As usual, the fan blows across the ridges of the heatsinks rather than
through them.
This configuration helps to channel the airflow out the back of
the case.

That green PCB is the fan controller. Because the fan is hardwired to
it, swapping the fan is a little more involved than usual.

The grill is typical of a 120mm fan unit: fairly unrestricted. The blue
power switch glows when the power is connected.

The fan is a high speed sleeve bearing model from Protechnic Electric.

This is unusual, as 120mm fans in previous Fortrons have been Yate Loon. In terms of
noise, sleeve bearing is good, high speed is not.


There are a total of seven cable sets, plus a 20-to-24 pin adaptor that’s about
4″ long. All cables are wrapped in a blue mesh sleeve.

  • 20″ cable with a 24-pin ATX connector
  • 20″ auxiliary 12V connector for processors that require it
  • 33″ cable with two 4-pin IDE drive connectors and
    one floppy drive power connector
  • 2 x 33″ cable with three 4-pin IDE drive connectors
  • 28″ cable with two SATA drive connectors
  • 20″ 6-pin auxiliary power connector for PCI Express

Very nicely finished, long output cables.

This is what Fortron calls a “Smart Housing Molex Connector”.

Advertising jargon aside, this style of Molex connector is much easier to use
than the standard kind.

In terms of features, the Blue Storm is in line with most other
power supplies in this power range: Generous cable lengths, and mesh sleeving
along with a pretty high standard of finish. The most notable feature is the
inclusion of Molex connectors with grips. This is a welcome addition, and we hope such connectors become standard for all power supplies
in the future.

In terms of noise, the only relevant features that are evident
before powering up the unit are the details of the fan. We may be somewhat optimistic
about the inclusion of a sleeve bearing fan in the unit, although the high speed
rating of the fan is not so promising.


For a fuller understanding of ATX power supplies, please read our article Power
Supply Fundamentals & Recommended Units
. Those who seek source materials
can find Intel’s various PSU design guides, closely followed by PSU manufacturers,
at Form Factors.

For a complete rundown of testing equipment and procedures, please refer to the
SPCR’s Revised PSU Testing System
. It 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 actual output load, which is exactly the way it is in a real PC
environment. But there is the added benefit of a precise 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 loads. It is, in general, a very demanding test, as the operating
ambient temperature of the PSU often reaches 40°C or more at full power.
This is impossible to achieve with an open test bench setup.

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 far too many variables in PCs and far 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 reasonably good overall impression of that person, but it is not quite the same as an extended meeting in person.

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. All other noise sources in the room were turned off while making the sound recordings.

Ambient conditions during testing were 20°C and 20 dBA, with input of 120 VAC
/ 60 Hz measured at the AC outlet.

DC Output (W)
AC Input (W)
Intake Temp (°C)
PSU Exhaust (°C)
Fan Voltage
Noise (dBA/1m)
Power Factor

NOTE: The ambient room temperature during testing
varies a few degrees from review to review. Please take this into account
when comparing PSU test data.


As mentioned above, despite the “500” in the model number and the
500W marketing blurb on the retail box, the Blue Storm is rated up to 460W.
Because of the discrepancy between these two numbers we feel that the 460W rating
may be more conservative (and truthful) than the ratings specified by many other
companies. This speculation is borne out by the fact that efficiency began to
rapidly decline at around the 460W mark. Many other power supplies exhibit this
rapid decline before their rated spec, indicating that they are operating beyond
their capabilities.

1. VOLTAGE REGULATION was good, ±4% or better on all lines at any of the test loads. The ATX 2.2 standard specifies voltage regulation of ±5%
on a positive lines, so ±4% is a reasonable margin of error

  • +12V: 12.11 to 12.45
  • +5V: 4.78 to 4.91
  • +3.3V: 3.19 to 3.30

2. EFFICIENCY was just short of top notch. The highest efficiency power
supply that we tested
peaked at 88%
. However, its efficiency peaks at 300W, and at 90W, the efficiency is a much lower 76%.
By comparison, the Blue Storm has an extremely flat efficiency curve, and its
peak efficiency is between 150W and 250W: right in the typical
power range. There are other power supplies that have
a higher peak efficiency, but these units typically reach this peak at wattages
that are beyond what most systems draw. Furthermore, the difference between
the highest and the lowest measured efficiency for the whole 460W range was
just 3%. Our measurements place the Blue Storm well above its rated efficiency
of >70%, and it is 10-17% more efficient than the last Fortron PSU we tested,
the FSP350-60PN

3. POWER OUTPUT: The Blue Storm had no trouble meeting its specified
maximum of 460W. It even ran for about 20 minutes at almost double its 160W
maximum rating for the +3.3V/+5V combination before we realized that we had
overloaded it. The wattage ratings of this power supply
may be more conservative than most, and this is a good thing.

NOTE on PCI-E CURRENT CAPACITY: There was some question about the maximum output capacity for PCI-Express because of the recent changes in the spec by Intel and nVidia. So to avoid confusion, a quick call was placed to Fortron. They confirmed that up to 75W was available on for PCI-e. The latest spec demands as much as 150W. As far as we know, PCI-e VGA cards that demand that much power are not on the market yet, but you should be aware that 75W is the recommended maximum on this PSU.

4. POWER FACTOR: There is no mention of power factor in any of the Blue
Storm’s marketing material or its specification sheets. However, its power factor
is in line with other units with passive power factor correction, which ranges between 0.63
and 0.67.

5. FAN & FAN CONTROLLER: The Blue Storm is unusual for a Fortron power
supply because its fan is manufactured by Protechnic rather than Yate Loon.
While the Protechnic is not the quietest fan we have heard, it is quite smooth,
and because it is a sleeve-bearing, it does not exhibit the clicking
so common in ball-bearing fans. A lower airflow version of this fan would have
been a better choice from an acoustics point of view, but given how “soon” the fan controller brings it up to
12V, this may not have been viable from a cooling standpoint.

The fan controller is quite responsive. Changes in temperature are quickly
mirrored by changes in fan voltage. The rate of change is close to the threshold
of perception. Listening closely, it is possible to hear the fan slowly increasing
in speed. However, it is unlikely that the changes in fan voltage are sudden
enough to be noticeable as background noise. Unless one is specifically listening
for the change in fan speed it is unlikely to be noticed.

There are two concerns that we had with the fan controller on the Blue Storm:

  • One is the start voltage. The low floor for the fan voltage seems to be around
    5.3 volts. Many competitive quiet PSUs start below 5V. In a system that is otherwise quiet, this difference
    is audible with the typical mid-to-low speed 12V fan employed in quiet PSUs.
  • The other concern is that it increases in voltage too soon. The
    fan voltage begins to increase at about 150W output, and by 200W output the
    fan voltage is 7.8V and it produces 36 dBA at one meter: No longer quiet. This is an active power range where changes
    in fan speed are likely to be audible. While this may be good design from
    a cooling standpoint, it is not such a good design from a low noise point of

6. NOISE: The noise of the Protechnic fan starts out mostly as airflow.
There is a small amount of low frequency motor hum that is noticeable
in an otherwise silent room, but it is fairly constant and inoffensive. As fan
voltage increases, the hum becomes more evident and increases in pitch, bringing
the noise further into the range of frequencies to which humans are most sensitive.

In a case, the starting noise level (and, most likely, the idle level) is pretty low, and probably good enough for most users. You may not want to sleep next to it, but during
daylight hours the ambient noise would probably be loud enough to cover it.
At higher loads, the hum of the motor could easily become irritating
as a background drone. It is the volume of the noise that is the problem, not
the character, so using this power supply in a low power system might be viable.
But, then again, why use a 460W power supply in a low power system?

MP3 Sound Recordings of FSP Blue Storm AX500-A

FSP Blue Storm AX500-A
@ <100W (26 dBA/1m)

FSP Blue Storm AX500-A
@ 150W (29 dBA/1m)

FSP Blue Storm AX500-A
@ 200W (36 dBA/1m)

There was no need to make recordings at higher power levels; it’s simply too loud.

Sound Recordings of Comparatives

Seasonic Tornado 400 @ 65W (19 dBA/1m)

Nexus NX4090 at @150W (24 dBA/1m)

Seasonic Tornado 400 @ 200W (24 dBA/1m)

Reference: Nexus 92mm case fan @ 5V (17 dBA/1m)


These recordings were made with a high
resolution studio quality digital recording system. The microphone was 3″ from
the edge of the fan frame at a 45° angle, facing the intake side of the fan to
avoid direct wind noise. The ambient noise during all recordings was 18 dBA or

To set the volume to a realistic level (similar to the original), try playing the Nexus 92 fan reference recording and setting the volume so that it is barely audible. Then don’t reset the volume and play the other sound files. Of course, tone controls or other effects should all be turned off or set to neutral. For full details on how to calibrate your sound system to get the most
valid listening comparison, please see the yellow text box entitled Listen to
the Fans
on page four of the article
SPCR’s Test / Sound Lab: A Short Tour.


The Fortron Source Power Blue Storm AX500-A is a great improvement over
the last Fortron PSU that we reviewed. Efficiency is definitely this power supply’s greatest strength.
Noise levels between the Blue Storm and the FSP350-60PN
measured within two dBA, but the Blue Storm
is quieter subjectively.

In a wider comparison with power supplies from other acoustics-focused manufacturers, the Blue
Storm fares less well. There are units with quieter fans and fan controllers
that output less voltage to a higher power output level, although few of them
will beat the Blue Storm in efficiency. Kudos to Fortron for using
a sleeve-bearing fan instead of a ball-bearing model, which would have been noiser. Still, this sleeve bearing fan was not really quiet enough to push the Blue Storm into the top ranks of quiet PSUs.

The retail pricing seems quite attractive for its power rating, but this is such a variable that it is difficult to comment on with confidence. The inclusion of Molex connectors with grips is also a point in the Blue Storm’s
favour. We look forward to seeing this feature on more power supplies from Fortron,
and hope that such connectors become industry standard.

Overall, the Blue Storm is a well-rounded power supply that suits many applications. Its flat efficiency
curve makes it suitable for use in both high and low power applications. Although
the noise it produces at higher output levels would be unacceptable to a hardcore
silencing enthusiast, it is likely that in a high powered system there would
be other, greater sources of noise.

* * *

Much thanks to Fortron
for the opportunity to examine the Power Blue Storm AX500-A.

Discuss this article in the SPCR Forums.

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