CoolMax 140mm Power Supply Review
By: Michael Phrakaysone
Edited By: Steve M. Silver


    Many people come to me with computer problems that, when assessed further, result from the power supply being dead or dying. The unfortunate thing is those people either skimp out on power supplies, or don’t know how to choose one. And there are far too many cheap power supplies on the market. The best advice is to choose a power supply that is heavy from a known, reliable company. The power supply is one of the most important components in a computer system for if the power supply is the weak link, instability will follow.

    CoolMax is a company that has produced power supplies for some time now and we have reviewed their power supplies before. They make quality products. CoolMax has introduced a new power supply unit (PSU) to their line-up in which they use a 140mm fan, making them one of the first companies to make use of this larger fan. Today I review the power supply in 400watt form.

    The CoolMax CR-400B arrived in perfect condition and was secured in Styrofoam to prevent any damage to the unit. The box is simple yet is pleasing to the eye. The package contains the 400W PSU, a power cable, a 4-pin to 8-pin connector adaptor (for use in PCI Express boards), and a 20-pin to 24-pin adaptor. This power supply is also SATA ready having a single SATA connector.

    The CoolMax CR-400B power supply is relatively heavy and sports a very nice black exterior finish. The finish actually isn’t as shiny as other power supplies I have reviewed (such as A+GPB) but looks good nonetheless and has a textured feel to it. There are many stickers around this unit spelling out quality control inspections and there is one sticker that says “Quiet”. Since this power supply is one of the first to implement a 140mm exhaust fan, I expected it to be virtually inaudible. The biggest advantage of a 140mm fan is that you can run the fan at much lower RPM’s yet have the same CFM airflow as an 80mm fan running at higher RPM.

    The rear of this unit shows an open design for exhaust air flow. The grille is a simple square type. This grille lets the hot air flow out efficiently. Now depending on your system setup, you are able to tweak the setting of the 140mm to your needs. There are four settings to adjust the fan’s RPM; high, medium, low and Auto. For most users, auto mode will be good enough. But for systems consisting of dual CPU’s that are hot, setting it to your desired value is quite invaluable.

    You can see the inside components very easily because of PSU’s open design. Inside sits two chunks of aluminum that help dissipate the heat generated from the power supply, big capacitors, the fan speed selector, and other materials. The layout of the inside is very clean and there are no visible signs of any connectors or wires hanging out or loose.

    This power supply comes with the ATX connector loomed and ready to go. Unfortunately the other wires are not loomed. This 400W model comes with 1 ATX connector, 1 P4 connector, 1 SATA connector, 1 AUX connector, 2 floppy connectors, and 6, 4-pin MOLEX connectors. There is a sufficient amount of connectors to meet most people’s needs.

Speaking of 400 watts, here is an image of the voltage rails that the CoolMax PSU sports.

+3.3V = 30A, +5V = 40A, +12V = 18A, -5V = 1A, -12V = 1A, +5VSB = 2.5A

This CoolMax 400W model supports the many features such as overload protection and over voltage protection so you can be assured that if you max out the power, the unit won’t blow up.


    I had this unit for a couple of months, enabling some “real world” long-term testing. I installed the CoolMax CR-400B both the test systems used here at Modsynergy (AXP and A64) for at least two months each under varying conditions. The CoolMax supplied solid and powerful voltage lines with little fluctuations. There were no signs of instability or unreliability to report – the CoolMax CR-400B passed with flying colors. As for noise, perhaps a major reason for considering this PSU, I only need to say that the first time I started it up on Auto I had to check if the fan was running because I couldn’t hear a thing!

Results - AMD Athlon64 system

Idle (30 mins)
Load (Toast 5 mins)
+12V = 11.93
+12V = 11.85
+5V = 5.14
+5V = 5.16
-12V = -11.89
-12V = -11.75
-5V = -5.02
-5V = -5.09


    The CoolMax CR-400B power supply is an established power supply featuring great power, features, and finish. You get a sense of the PSU’s great quality just by looking at it. Not only are the wire connectors gold plated but so is the fan grille. The140mm exhaust fan is virtually inaudible in PC operation. On top of all of its excellent features, it is inexpensive. In fact, I think the CoolMax CR-400B could be the best power supply for the money that I have tested. I have no hesitation in recommending this power supply to anyone. For the price and what you receive with it, this power supply deserves your hard earned dollar.

Pros and Cons

  • + Price
  • + Gold plated connectors
  • + Good, reliable power
  • + SATA ready
  • + Bundled adaptors
  • - The wires other than the ATX connector are not sleeved.
  • - Only a single SATA present; two connectors is preferred for people doing RAID
  • - May have a portion of the PSU fan blocked for some cases with PSU support brackets (not a con for the PSU)

I would like to thank CoolMax USA for making this review possible.

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