Coolmax CU-400T & 600T Detachable Cable PSUs

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The 400W and 600W models differ slightly in their internal components, and especially in their heatsinks. The main transformer in each model has a different model number and some components seem to have been shuffled around a bit. This is to be expected: Higher quality components with greater capacities and higher efficiency are necessary to output the additional power required by the 600W model.

The most noticeable difference between the two models is the size and design of their heatsinks. The heatsinks in the 400W model are small and thin, and do not provide much surface area. In contrast, while the heatsinks in the 600W model are still quite small, their finned design provides them with far more surface area, which should translate into an equivalent gain in cooling effectiveness.

The 400W model has tiny heatsinks. Are they really enough to cool it effectively?

The heatsinks in the 600W model are more substantial, although still pretty small.
An additional PCB, whose purpose is unknown, has also appeared over the AC socket.

The fan bears the name "T & T", which stands for Tranyoung Technology, a fan OEM in Taiwan. Deciphering the model number on their web site reveals two important attributes: The fan is a sleeve bearing model, and it is low speed. Although sleeve bearings don't last as long as ball bearings in high temperature conditions, they tend to be quieter. While a sleeve bearing fan is not the best choice for a system that will see heavy use, and thus many hours of operation under high heat, it is a good sign for those seeking a quiet power supply.

"L" stands for "Low Speed", "S" stands for "Sleeve Bearing" ¬ó both excellent signs.
The 0.4A power rating suggests a higher speed than most low speed fans, however.


All the cable sets are removable, even the main ATX cable. The cables are sleeved in black plastic mesh to keep things nice and tidy. The advertised "Ohm-Leg" plugs are probably the improved Molex connectors that can be be removed by squeezing the grips on either side of the plug.

A word of warning about the socket for the SATA connectors: The five voltage pins for this connector protrude beyond the top edge of the plastic frame. This means there are live, bare contacts on the outside of the power supply when the unit is powered up. Not only does this increase the odds of an accidental short circuit, but it could be a hazard for those who like to poke around inside their computers while they are running (you know you're out there).

Each model comes with seven cable sets:

CU-400T (400W)

  • 16" sleeved cable for main 20+4 ATX connector
  • 17" auxiliary 12V connector
  • 16" 8-pin auxiliary power connector for dual CPU
  • 19" cable with two 4-pin IDE drive connectors
  • 2 x 24" cable with two 4-pin IDE drive connectors and one floppy drive power connector
  • 21" cable with two SATA drive connectors

CU-600T (600W)

  • 16" sleeved cable for main 20+4-pin ATX connector
  • 18" auxiliary 12V connector
  • 18" 8-pin auxiliary power connector for dual CPU
  • 27" cable with three 4-pin IDE drive connectors
  • 2 x 27" cable with two 4-pin IDE drive connectors and one floppy drive power connector
  • 25" cable with two SATA drive connectors

The cable lengths are a little on the short side, especially the IDE drive connectors that usually need the extra length to route the cables properly.

There are more headers on the power supply than there are supplied cables. There is one Molex header and one SATA header that do not have corresponding cables. As mentioned, the PCIe header also lacks a cable. At the time of writing, CoolMax did not list additional cables as purchasable items on their web site, and I was unable to find detachable cables for sale.

The black sleeving keeps the individual wires together. They look quite snake-like.

As mentioned above, it is very important to remember to plug in the extra three-pin plug that is bundled with the main ATX header.

Don't forget to plug in the remote sensor plug!

The implementation of the 4 + 20-pin ATX header is a little unusual. Instead of making the two parts of the plug completely separable, the extra four pins are designed to hinge to the side when they are not needed. This reduces the possibility that the header will be installed improperly (with the standard design, it's possible to fully insert the 4-pin portion without properly seating the 20-pin header), but may pose a compatibility problem depending on the position of the ATX socket on the motherboard.

The 20+4 style ATX connector is an unusual design.

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