Hial Noobt <[log in to unmask]> wrote:
> Say, a system has Cd-ROMS drives, hardisks and other peripherals and only
> using a 200W power supply instead of 250W or 300W. What are the ill effects?

If the power supply is not big enough, there are several things that can happen.

1.) The system may be unstable as some of the voltages drop below spec.
2.) The increased load on the switching supply circuits may cause increased
noise and spikes on the supply voltages, again leading to unstable operation.
3.) The power supply could simply "shutdown" either because of over current
detection or thermal overload.
4.) The power supply could overheat damaging the supply itself, or increase the
temperature in the case.

These problems are likely to be worse as the temperature increases. While it is
unlikely that physical damage would result to any of your peripherals (but it IS
possible), unstable operation or sudden shutdowns could cause you to lose data.

To determine the proper size for the power supply, "wattage" is not good enough.
The supply itself should list the current capabilities for each of the supplies
(+/-5v and +/- 12v). You then need to look at the spec for ALL your peripherals
(don't forget the motherboard and cards) and add up their requirements. Make
sure none of them exceed those of the power supply.


--
Russ Poffenberger               Engineering Specialist
Schlumberger Technologies ATE   DOMAIN: [log in to unmask]
1601 Technology Drive           CIS:    72401,276
San Jose, Ca. 95110             Voice: (408)437-5254  FAX: (408)437-5246