fred said:
I dropped my desktop and noticed the cpu cooler had come off.I reapplied
heat paste and clipped it back on.I reseated all the cards( memory cards
etc.)and all the plugs.The power comes on and all the fans are working,
and the hard drive is spinning.When turned on I only get a blank black
skreen. What should I check for first.HELP.
I have xp pro
The easiest way to get a response from the computer is.
1) Turn off the power and unplug the computer. Any time you work inside
the computer, there should be no power present. Unplugging the computer,
while it removes ground from the computer, is an easy way to know
for sure there is no power inside.
2) Pull out the RAM sticks, making note of how that fit, where the notch
is related with respect to the key in the memory slot. Write down
which memory slots are used, so you can put them back later. Store the
RAM in an antistatic bag. If you keep the antistatic bags that hard
drives come in, eventually you should have a good collection of bags
to use for temporary storage.
3) With the RAM removed, when the computer starts, it should "beep" an error
code. Some computers have either a speaker, or a piezoelectric speaker on
the motherboard. It may beep two or three times in a row, then a period
of silence, and the error code repeats. This is a good sign, because it
means the processor is executing BIOS code. Certain Dell computers have
four LEDs, and one of the codes on the LEDs, says "bad RAM" or the like.
4) If the computer won't beep, then the processor is likely not
running.
a) Check that the ATX12V 2x2 square power connector is in place.
The cable has two yellow and two black wires. Such a power cable
is present on computers for at least the last five years. If the
computer is much older, you won't have a power cable like that.
b) Verify the CPU is seated in the socket. Undo the clips on the heatsink,
so you can get at the processor. Undo the lever on the side, so that
the CPU can be removed. Verify the pins or contacts are in good shape.
Do not touch the gold pins or contacts, as that leaves grease or salt
on the pins. Handle the processor by the edges, to keep it clean.
Put the CPU back and close the lever again. Add fresh thermal paste (only
a thin layer -- it should not ooze out all over the place). Clean off
the base of the CPU heatsink, then put it back. Fasten the clips etc.
If you apply too much paste, it'll get into the socket and make
the electrical contacts unreliable. If you have the right amount,
you'll only see a thin bead of paste, when you view the heatsink/CPU
sandwich from the side.
5) If you're still not getting error beeps, with the RAM removed,
then it could be the motherboard has a crack in it. I'm assuming
your fans are running - running fans means +12V supply voltage is
present and working. And the CPU needs power like that too.
You can simplify the computer setup, by unplugging a bit of hardware
at a time, and retesting. Eventually, you can end up with the
motherboard sitting on your work table, the power supply, a
switch for the front panel Power button, and do a test that way.
The intention is to try to remove anything which might prevent
the computer from starting.
Processors are pretty reliable. Power supplies are less reliable.
Motherboards are pretty good, except if you know they've been abused.
They cannot take an infinite amount of abuse. Dropping a computer
off a desktop, means the CPU heatsink will be tugging on the mounts,
and can crack whatever is supposed to hold it in place. Stresses can
also cause solder joints to crack. In some cases, flexing the
motherboard may exercise an intermittent connection. And then
you'll forever have an unreliable computer - the intermittent
connection can open whenever it feels like. Replacing the
motherboard would be a solution in that case.
Paul
