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B. COOLMAX
CF-480B
Coolmax offers several fanless models, 350W, 400W and 480W; the last is the
one we're examining here. We
reviewed a 300W fanless Coolmax previously. It's surprising that the current
model looks so similar, considering the first sample was received was over six
years ago. There have been tremendous improvements in computer PSUs in those
years.
There were inconsistencies in labeling and specifications between the web site
and the PSU label. Still the presence of the RoHS sticker, a three-year warranty,
and more current/power on the 12V lines than on the lower voltage lines (according
to the
web site info) are encouraging.
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Coolmax CF-480B Specifications
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AC Input
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115/230V @ 50/60 Hz
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DC Output
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3.3V
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5V
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12V1
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12V2
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-12V
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5Vsb
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28A
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20A
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10A
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16A
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1A
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2.8A
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180W
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280W
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12W
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14W
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452W
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Modest size/appearance retail box for the Coolmax. The photos on the
box are slightly misrepresentative; the actual PSU has no vents on the
sides.
There's no printed manual, but a sheet with links to download a PDF copy.
The PSU itself uses extruded aluminum for its outer casing, with large
vent grills on the front and back. It weights about 4 lbs. There are no
vent holes on the sides, top or bottom.
The bottom is a serious heatsink-style extrusion... which takes the place
of a 120mm fan. The inside panel is quite an open grill. The front/back
open grills enable cooling airflow through the PSU, especially
if there is an exhaust fan on the back panel of the computer case; it
will tend to suck air from the outside through the PSU.
The output cables are mostly quite long, and only the main 20/24-pin ATX
cable is sleeved. There is one PCIe 6-pin connector.
Even though the label suggests a switch for 115V/230V, there is no such
switch. The PDF manual also states the Voltage Selector should be set
to 115V or 230V. One assumes the PSU was upgraded for auto-range AC input
but the manual and tags not changed. 230VAC operation was not checked.
NOTE: The output specs on the label differ from those given on the product
website; we used the web site info for our loading formula.
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TORTURE TEST SUMMARY
Coolmax CF-480B
480W Rated Output
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Duration
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Output (W)
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Efficiency
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Hotbox °C
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Power Factor
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10~20 min
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22.0
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48.9%
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24
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0.69
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43.2
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60.8%
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25
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0.82
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66.1
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68.1%
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27
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0.85
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92.1
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72.0%
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32
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0.86
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151.0
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72.8%
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35
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0.88
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198.7
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73.4%
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38
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0.89
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251.0
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73.1%
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43
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0.89
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478.0
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68.9%
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62
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0.93
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15 hr
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251.0
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72.2%
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43~46
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0.89
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15 hrs
(w/ Fan)
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400.5
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71.5%
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43~45
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0.93
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478.0
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68.9~67.0%
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44~47
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0.93
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+12V Ripple (peak-to-peak): <90mV @ <250W
~ 130mV @ 400W
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Output Voltages during 15 hr test:
250W - 12.2V, 5.10V, 3.37V
460W - 12.2V, 5.04V, 3.33V
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AC Power in Standby: 0.3W / 0.2 PF
AC Power with No Load, PSU power On: 14.7W / 0.97 PF
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OTP Shutdown: Almost immediate shutdown at 400W.
No-fuss recovery. Repeated several times without incident.
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ANALYSIS
The CF-480B turned out to have efficiency in the low 70s, similar to the first
fanless PSU from Coolmax we reviewed all those years ago. The change to auto-range
AC voltage input was not accompanied by an improvement in efficiency, but Active
PFC was probably part of the change, as the PF was quite high.
Overall electrical performance, apart from the low efficiency, was solid throughout
the short term testing. Electronic noise / whine was modest enough to be ignored.
Not surprisingly, the unit ran quite hot, with the casing reaching over 80°C
in spots at 400W load. At 400W output, the Coolmax has to dissipate a whipping
160W of heat, compared to just 44W for the Seasonic X-400.
The sample passed the 250W torture test without issue. OTP shutdown occurred
very soon after the 400W test was started. It restarted after cool-down without
any problem, but overheated and shut down again in a few minutes. The Nexus
120 fan at full speed was added to blow air out of the hot box. At that point,
it ran successfully for a couple of hours, but OTP shutdown occurred when the
ambient room temperature exceeded 26°C in early afternoon. The Scythe Gentle
Typhoon 120mm fan was installed as the exhaust fan and run at full speed (~1500
RPM). The increased airflow kept the hotbox temperature under 43°C, and the
Coolmax successfully ran at full power for 15 hours.
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