computer shuts down, help please

[maglee]

about a month ago my computer start shutting down all by itself but the computer is running and there is no picture I want to know if you can tell me why it is doing this.
I have gotten a bigger monitor for it a 21" but I tried the smaller monitor and it still does the same thing. Do you know why I am having this problem. I have replace the video card as I thought that was the problem, but it still does the same thing with new card.
the computer is still running but the monitor has no picture and it will stay this way for a day and then the next day it will work fine. but then it will shut off again and won't go back on till the next day.
please reply with some tech help.
Thank you
Margurette lees
AMD Duron 800Mhz processor
200mhz system buss speed
128 KB level 1 cashe
64KB level 2 cache on die.
128 ram 20 GB hard drive
I run win 98 os
Please tell me where I can get help to fix this problem

[jtdoom]

Hi

let's test something?
turn the computer off, and then switch it off at the back or kill power on the powercord. (switch off powerstrip, or pull from wall)

hit the on/off button on front couple times
(what will help drain residual voltages)
leave it without power for ten minutes or so.

then give it power, and turn it on.
watch the screen closely.
when it runs, check time and date
if date/time is OFF, correct it.

let it sit there for as long as it takes to go in standby, wait fifteen more minutes
(some things go in standby sooner than others)
and then try get it out of standby

========
when it reproduces the problem,
again turn the computer off, and then switch it off at the back or kill power on the powercord. (switch off powerstrip, or pull from wall)

hit the on/off button on front couple times
(what will help drain residual voltages)
leave it without power for ten minutes or so.

then give it power, and turn it on.
watch the screen closely.
when it runs, check time and date
if date/time is OFF, again correct it.
(if it dood it again, it tells you the CMOS battery is dead.)

if time is correct, again let it sit there for as long as it takes to go in standby, wait fifteen more minutes
(some things go in standby sooner than others)
and then try get it out of standby

if it again reproduces the fault, then I think you have to think about replacing the power supply unit
(replace with a better quality PSU).

but... we'll test something else too
now you pull USB devices out before you run this same test.

let us know result of these three tests?
wanna know what doing this actually does ?
it tests ACPI functions (and something called a flipflop can refuse to flip back on when powersupply is too weak or bust) and it tests CMOS battery.

if the CMOS battery is dead (date/time is again off after the second time you pulled power), replace it
(erm, if it connects to a timeserver on the internet, make sure it cannot get on the net during these tests, or kill this function)

if the fault goes away when no USB devices are connected, it can still mean that the powersupply is too weak.
but, I would want a second opinion then.
anyway, let us know what happens... it will take couple hours to do this.
the weather is fine, the garden is lovely, and you don't have to sit and watch it go into standby...
;)

[jtdoom]

I say, watch the screen closely, but I forgot that most computers "hide" what goes on with a splash screen.

this is a BIOS setting;
silent/quiet boot it is the first thing I turn off when I have to look at a machine...

windows splash screen is the second thing I turn off (using tweakui to do this)