At 17:41 01/14/07, Andrew J. Rozsa <[log in to unmask]> wrote:
>1. I come to believe that my system's PS is suspect. I would like to 
>replace it....
>2. The slot fan I got has two power plugs: a male and a female. I 
>connected the female to a connector from the PS. Nothing happens.

Is this is the only reason that you suspect your power supply? If so, 
your suspicion may be unfounded.

As strange as it may seem, you can't power up your fan using its female 
plug. I've tried that and it didn't work. (The female connector is for 
providing power to another device after you have supplied power to the 
fan's male connection.) You must provide power to the male power plug 
on the fan.

If your power supply has no free female molex drive plugs (these plugs 
have four wires that provide 12V for drive motors, ground, ground, 5V 
for the logic on drive circuit boards), you should unplug another drive 
or fan inside your computer and use the female connector that was 
powering that device for the slot fan. Then plug the device that you 
just disconnected back into the female plug coming from the fan. If the 
bundles of wires coming from the power supply (inside your case) aren't 
long enough, you can buy a male molex to female molex extension cable. 
Or else buy a "Y" splitter (male molex splitting into two female 
molexs) and attach it onto one of the outputs of the power supply to 
end up with a free female connector for the fan.

Note that most power supplies provide several cable runs (cable 
bundles), several providing (typically) two female molex drive 
connectors each. (One of the drive connectors may be a small one meant 
for a floppy drive.) A newer power supply might have cable runs ending 
with connectors for SATA drives which are not useful for older drives 
or fans. (SATA drive motors use 12V but their logic uses 3V instead of 
the 5V used by older IDE drives, now called PATA drives). There are 
also different cable runs for the 20 or 24 pin motherboard connector, 
the auxiliary processor power plug, and an auxiliary video card power 
plug. If you intend to buy a new power supply, determine whether you 
need a 20 pin or the 24 pin motherboard cable. And decide whether you 
need the auxiliary P4 or video power connectors, and how many and what 
type (white molex or black SATA) drive power connectors you need. Also, 
if possible, check the number and positions of the screw holes on the 
back of a prospective power supply and make sure they match the screw 
holes for mounting a power supply on the back of your computer case.

You can add splitters to cable runs to get more female power outputs 
but should not end up with any one cable run providing power to too 
many drives. (Too much power going through one wire can cause it to 
overheat, increasing its resistance, and thus decreasing the voltage 
output. This can cause hard drives to have intermittent read or write 
failures. (I know from experience here, after trying to connect four 
hard drives to one power supply cable run. For example, each hard drive 
may use up to 30 Watts. Four of them could need 120 Watts. At 12 volts, 
that's 20 Amps of current. But the folks at PCP&C warned me that the 
typical red, black or yellow wires used in cable runs should not have 
more than 10 Amps going through any individual wire. Too much current 
can even case the wires or connectors to burn.)

Check out <http://www.pcpower.com/technology/power_usage/>.

Regards,
Bill 

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