Power supply guide

The following is a discussion of what to look for in a power supply for a HTPC. It is based on my own experiences and information gathered from various AVS forum members. As such this article reflects my views on the subject, which may differ from that of others. Don't forget to check out the links page if you want to find further information on HTPC related topics.

The actual output (expressed in watts) of a PC power supply is critical in that it determines the number of devices you can safely connect without overstressing the power supply and causing peaks and dips in the voltage supply to components in the PC. There is one rule of thumb with power supplies - the bigger the better. Getting a large capacity power supply of 400 - 500W will ensure that the power supply will be able to effortlessly supply all the power that the components need. It will also run cooler because in most cases it will be running well below capacity. It is worth noting that the power supply can be one of the largest generators of heat within a PC, thus a large capacity power supply will lessen the amount of case cooling required (and hence noise).

Another desirable feature in a power supply is tight regulation on all voltage lines (within 5% is ok, 3% is very good) through feedback circuitry. Some computer components (eg. Intel CPU's) are very discerning with regards to how tightly regulated the voltage lines are and cheap power supplies can sometimes cause system instability.

For HTPC use it is desirable to have the power supply operating as quietly as possible. There is nothing worse than hearing the whir of PC fans when you are trying to listen to a quiet scene of a movie. Power supplies with thermostatically controlled fans that increase in speed only when the temperature inside the case rises can cut down noise considerably. Some can even control the case fans thermostatically as well (ie. Antec Truepower).

There are many good brands of power supply available on the market that have many of the above features including Antec (available here), Enermax and Topower. Power supplies tend to be one of the most overlooked items in the computer in terms of quality. For HTPC use in particular, using a good power supply will pay big dividends in terms of system performance and noise level.

- Chad