Coolmax CU-400T & 600T Detachable Cable PSUs

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July 10, 2005 by Devon Cooke with Mike Chin

CoolMax Taurus CU-400T / CU-600T
400W / 600W ATX power supply w/ detachable cables
CoolMax Technology Inc.

Market Price

400W: ~US$60 / 600W: ~US$120

CoolMax sells a number of power supplies under its Taurus marquee. SPCR has reviewed a Taurus before: CoolMax had one of the first fanless power supplies on the market in its CF-350B. Their CU-x00T series bears little resemblance to the fanless model, but CoolMax still refers to it as a Taurus. To add to the confusion, the manual and the label on the power supply list the model number as AP-x50X, with CoolMax's "official" model number listed in parentheses.

The distinguishing features of the CU series are detachable cables — "EZ Wires" — and a three-way fan switch that is common to most of CoolMax's fanned models. It is also available in three different finishes: Glossy black, a dark silver-gray, and a metallic white. Three different capacities are available, of which we are testing two: The 400W model and the 600W model. The remaining model comes in at 500W.

In the box: The power supply, two bundles of cables, an AC cable, plus an eight page manual.

The eight page manual is really four pages long: The remaining pages are completely blank. Aside from the colorful front cover, there is nothing to identify CoolMax as the company responsible for the product, and it even lacks the usual warranty and copyright notices. No contact information (not even a web site) is included with the product.

The Coolmax company's web site provides an address for their head office in Taiwan, but no phone number was listed. Customer service seemed to be limited to e-mail or post. However, a related web site for Top Tech USA, which is the US arm for Coolmax, does provide a page of US contact information that includes an address, telephone number and email address. No warranty or service information of any kind is provided.

Feature Highlights from the manual of the CoolMax Taurus CU-x00T series


Smart detachable cable design allows you to connect cables you actually need, therefore improve internal airflow and avoid system clutter.

A good reason to buy a unit with detachable cables.

Innovated voltage sensor circuit reduces voltage drops, make sure the PSU provides enough power to your system.

A variant of the standard voltage regulation circuit that measures the voltage at the ATX plug instead of at the source of the wire.

All kinds of protection circuits (OVP/OPP/SCP).

Maybe not literally all kinds, but these are probably the most important.

High efficiency: not less than 75% at full load.

This seems slightly dated; 75% efficiency isn't especially high these days.
Externally selectable 3-band TMS (Thermal Management System: Auto/Low/High) to meet vast majority end users' demands.
It's nice to have options.

12cm fan.

The de facto standard these days.
S-ATA ready. Another standard issue feature.
Cable-tidy design and user friendly Ohm-Leg plugs. Mesh sleeves for the cable sets. Ohm-Leg? Your guess is as good as mine.

Depending on where you look, the specifications for the power supplies give conflicting information. Amperage ratings and even the number of rails are incorrectly listed on CoolMax's web site: There is an erroneous rating for a -5V rail. However, double checking the pin hole in the ATX connector revealed that no such voltage was supplied, as per the more recent ATX12V specs. The spec label for the 400W model is shown below:

A couple of things stand out in the specs for the 600W model:

  • The +12V rail is rated for 32A — well over the 20A limit that Intel recommends on a single +12V rail.
  • The +5V rail is rated for a whopping 60A, double many other similarly rated power supplies.

The fact that there is only a single +12V rail for a power supply of this capacity means that the power supply does not comply with Intel's latest ATX12V v.2.x PSU Design Guide. Most likely it was designed to conform to ATX12V v.1.3, which is the only version of the specification that lacks the -5V rail but does not specify multiple +12V lines for capacities above 20A. However, no mention of ATX12V could be found in any of the documentation related to the power supply. The box does say "ATX Power Supply", but ATX is not the same thing as ATX12V, and no version number is listed.

Much of the additional capacity that the 600W model is capable of seems to come from the excessive 60A rating for the +5V rail. Using Ohm's law (P = VI), this works out to 300W — far more than anyone could realistically draw in a powerful modern system. The strength of this line is further evidence of the ATX12V 1.3 lineage of this model. Power supplies of this vintage were designed to supply the processor from the +5V rail rather than the +12V rail that is commonly used today.

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