Classic signs of a failing Power Supply Unit

If renewing a PSU check:

1. The physical size of your PSU, some are hard to replace due to being a non standard size.

2. The amount of power need from the PSU don't skimp. 3 The correct connections for your equipment

3. Physical Dimensions

Besides the specs and form factors, the physical dimensions are also important factors in selecting a compatible power supply. Here is an outline of the physical dimensions of most standard power supplies:

• ATX: 6x3.5x5.5", HxWxD. Most common. Uses 4 mounting screws.
• Mini-ATX: 5x3.5x5", HxWxD. Rare size. Uses 4 mounting screws. Can be used in a regular ATX case, but often not the other way around.
• MicroATX: 5x3x4", HxWxD. Use 3 mounting screws. Not interchangeable with ATX or miniATX.
• Flex ATX: Even smaller than Micro ATX. Various sizes according to case specs; often not interchangeable.

Use the data above to determine if a particular power supply would fit your case.

The quality of a power supply can be estimated by its weight. While this is not a true scientific or thorough measurement of the power supply reliability, it is nevertheless a very simple and easy way for ordinary PC users to estimate and compare the quality of a power supply. Why weight matters http://www.directron.com/psu.html

1. Power supply calculator http://www.antec.outervision.com/

2. Correct connections Some boards have 20 pin connectors others 24 pin There is often a 4 pin plug required to power Intel CPUs Molex D plugs for IDE HDD and CD/DVD drives SATA power connections for latest HDDs and DVD drives.

Guide to changing PSU http://www.quietpcusa.com/psuinstall.html http://compreviews.about.com/od/tutorials/ss/DIYPSU.ht

HP and compaq PSU problems guide http://h10010.www1.hp.com/ewfrf/wc/document?lc=en&dlc=en&cc=us&product=3739786&docname=bph06788