X-bit labs

X-bit Labs Presents: Power Supply Unit Testing Methodology In-Depth (page 10)

Category: Other

by Oleg Artamonov

[ 01/03/2008 | 10:43 AM ]

Short Circuit Protection (SCP)

Short circuit protection is obligatory according to the ATX12V Power Supply Design Guide. This means that it is implemented in all power supplies, even those that don’t explicitly mention such protection, that claim to comply with that standard.

Overpower (Overload) Protection (OPP)

This protects the power supply from overload on all of its outputs combined. This protection is obligatory.

Overcurrent Protection (OCP)

This protects the separate PSU outputs from overload (but not yet from short circuit). It is available on many, but not all, PSUs, and not for all of the outputs. This protection is not obligatory.

Overtemperature Protection (OTP)

This protects the PSU from overheat. It is not required and is not implemented often.

Overvoltage Protection (OVP)

This protection is obligatory, but is only meant for critical failures. It works only when some output voltage shoots 20-25% above the nominal value. In other words, if your power supply yields 13V instead of 12V, you must replace it as soon as possible, but its protection is not required to react yet because it is designed for even more critical situations.

Undervoltage Protection (UVP)

As opposed to too-high voltage, too-low voltage cannot do much harm to your computer, but may cause failures in operation of the hard drive, for example. This protection works when a voltage bottoms out by 20-25%.

Nylon Sleeve

Soft braided nylon tubes on the PSU’s output cables help lay them out neatly inside the system case.

Unfortunately, many manufacturers have switched from the undoubtedly good idea of using nylon sleeves to the use of thick plastic tubes, often screened and covered with a paint that shines in ultraviolet. The shining paint is a matter of personal taste, of course, but the screening does not do anything good to the PSU cables. The thick tubes make the cables stiff and unwilling to bend, which makes it hard to lay them out in the system case properly and is even dangerous for the power connectors that have to bear the pressure of the cables that resist the bending.

This is often advertised as a means to improve the ventilation of the system case, but I can assure you that the tubes on the power cables have but a very small effect on the airflows inside your computer.

Dual Core CPU Support

This is nothing but a pretty-looking label. Dual-core processors do not require any special support from the power supply.