PC power related questions

hi, all

The other day I was poking around insides of my computer. I took out
the motherboard, disconnected all the cables and power cords. After I
done with my research (I was in the process of fitting a new
motherboard into my pc), I put everything back in and reconnected the
power. But the computer won't power on, I rechecked the connections
but everything seems fine, motherboard power indicator was on, I got
voltage output through the 20-pin motherboard power connector. But the
machine simply wouldn't turn itself on by the power switch. I was
really puzzled and thinking I might fry something on the board. So I
did a step by step component check, and was surprised to discover the
heat sink fan wasn't properly inserted onto the mother board when I
put things back together (it's a Intel 440BX motherboard and Intel
PIII 600Mhz processor combination), once I fully inserted the heat
sink of the processor, system is back to normal.

I have a couple of questions:

1. how does the heat sink related with system power? Is it always true
that the system power will only deliver once the heat sink is in place?

2. I noticed on the 20 pin motherboard cable, only one pin has voltage
( a 5V), but I know the 20 pin cable delivers different level of
voltages to the system (12v, 5v, 3v, etc). is it because those lines
didn't detect any loads hence it won't deliver power? ( I
disconnected the power cable from motherboard during voltage
measurement).

3. I have Dell dimension T600 mini-tower system and it's equipped
with a Intel 440BX motherboard, does anyone know if it's ATX
compliant? I couldn't fit a ATX motherboard onto the chassis.


Thanks in advance.

wrote:
hi, all

snip

I have a couple of questions:

1. how does the heat sink related with system power? Is it always
true that the system power will only deliver once the heat sink is in
place?
Was the fan connected? Some won't start until it is. The processor might
have thermaled out, telling the p.s. to shut down...usually this takes a few
seconds. If so, lucky you didn't fry the cpu.

2. I noticed on the 20 pin motherboard cable, only one pin has voltage
( a 5V), but I know the 20 pin cable delivers different level of
voltages to the system (12v, 5v, 3v, etc). is it because those lines
didn't detect any loads hence it won't deliver power? ( I
disconnected the power cable from motherboard during voltage
measurement).

Yes, there are dummy loads, usually a few light bulbs, that you can connect
in order to test the p.s. without a computer, but they won't turn on unless
the mb tells them to....

3. I have Dell dimension T600 mini-tower system and it's equipped
with a Intel 440BX motherboard, does anyone know if it's ATX
compliant? I couldn't fit a ATX motherboard onto the chassis.

You answered your own question...probably a Dell special order from Intel.
Dell makes enough computers that they can special order anything they want,
and you have to go to them for repair parts and upgrades...unless you can
find what you need from another Dell....

jak


Thanks in advance.