The Coolmax V-500 costs only USD 22 at and, therefore, we were very skeptical that it could deliver its labeled wattage, 500 W. Wattage, as we always explain, isn’t everything. Let’s see the other downsides of using a cheap power supply.

The reviewed power supply doesn’t have an active PFC circuit, has a manual 115 V/230 V switch, and is based on the obsolete half-bridge design.

Coolmax V-500 power supplyFigure 1: Coolmax V-500 power supply

Coolmax V-500 power supplyFigure 2: Coolmax V-500 power supply

The Coolmax V-500 is 5.5” (140 mm) deep, using a 120 mm sleeve bearing fan on its bottom (LY 1225L12S ND1).

This unit doesn’t have a modular cabling system, and only the main motherboard cable has a nylon sleeve. This power supply comes with the following cables:

  • Main motherboard cable with a 20/24-pin connector, 14.6” (37 cm) long
  • One cable with an ATX12V connector, 15.7” (40 cm) long
  • One cable with one SATA power connector, 15.4” (39 cm) long
  • One cable with two peripheral power connectors, 15.4” (39 cm) to the first connector, 5.9” (15 cm) between connectors
  • One cable with two peripheral power connectors and one floppy disk drive power connector, 15.4” (39 cm) to the first connector, 5.9” (15 cm) between connectors
  • One ATX12V/EPS12V extension, 6.7” (17 cm) long

There are several major flaws here.

First, all wires are 20 AWG, thinner than the minimum recommended (18 AWG).

Second, the number of connectors is simply ridiculous for a power supply labeled as a 500 W product, with no video card power connector and only one SATA power connector. Even very basic computers nowadays require at least two SATA power connectors, one for the hard drive and another for the optical drive.

Third, there is a -5 V (white) wire on the main motherboard cable, wire that was removed from the ATX12V specification in January 2002, almost 10 years ago. Therefore, this power supply uses an obsolete design. Inside the power supply, we could clearly read a marking saying that it is an ATX12V 1.3 model (the ATX12V specification is 2.3), but the box says this unit is an “ATX12V 2.01” unit. This is wrong for two reasons. First, there was never a 2.01 ATX12V specification. Second, the correct name is ATX 2.01 specification (and not ATX12V), which only specifies the physical dimensions of the power supply housing.

Coolmax V-500 power supplyFigure 3: Cables

Let’s now take an in-depth look inside this power supply.

Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.