Help ! dead PC after memory upgrade

  morris948 17:29 15 Nov 2008

i have a PC which has a foxconn motherboard K8S760MG.WinXP OS.
It was working fine, when i upgraded the memory from 256mb by adding an extra 1gb to a spare socket (memory from crucial), and then i cleaned up some of the dust from the cpu fan and cooling fins with a vacuum cleaner.
When i finally powered up, the fans came on, and thats it, there is no BIOS beeps, the hard drive does not spin up and the DVD and CDROm drives do not operate when you open the drawers.
I checked the voltages going to HD and DVD /CDROM, and 5V and 12V are present, i checked the power supply socket and all voltages are present and correct.
I then removed the extra memory to put things back as they were, but no joy.

I have checked all jumpers are in the correct places and all are present, i have not touched anything.

can anyone help explain what has happened here.

  chub_tor 17:40 15 Nov 2008

Can you actually get into the BIOS screen by tapping Delete or is this function also not available?

  morris948 17:42 15 Nov 2008

No, the monitor stays off, hard drive is not starting up.

  Fruit Bat /\0/\ 17:46 15 Nov 2008

Remove old memory and fit new memory in its place, ensure memory is fully inserted in the slot.

  chub_tor 17:54 15 Nov 2008

If you have put your old memory back in and still have the boot up problem then you can rule the new memory out as being the problem. So it must be something to do with your "i cleaned up some of the dust from the cpu fan and cooling fins with a vacuum cleaner."

Was the PC switched off at the mains when you cleaned it out? Did you touch any parts of the motherboard with the vacuum cleaner?

For an almost total failure - you say the fans came on (do they stay on when you power up? Which fans do you mean? - it has to be a motherboard connection disturbed, or a motherboard failure or a power supply failure.

Can you swap the power supply with a known good one? That would rule out the most obvious.

But first I would have another good look at all the motherboard connections, power, re-set switch, power switch, etc to make sure that you haven't knocked one off or knocked two pins together.

  morris948 17:58 15 Nov 2008

I have fitted new memory in slot 1 and removed old, no change.
Other observations are keyboard lights come on for one second at power up, have tried with just the hard drive connected only (floppy / DVD and CDROM cables disconnected, no change.
i tried with no memory in place - no change.

Power on switch on PC does not switch off the PC after pressing it for 5 seconds, have to use rocker switch on PS at back.

  morris948 18:03 15 Nov 2008

I removed the fan from the heatsink assy, as i was unable to get the heatsink off, i cleaned i
the dust out using a hand held dyson vac, not very powerful, i was very carefull not to touch any components.
Yes, the fans stay on , that being the CPU fan and the power supply fan.
Using DVM, all voltages are present according to mobo manual

  morris948 18:06 15 Nov 2008

i have tried disconnecting all the cables and reconnecting them on the mobo -no change

  morris948 18:22 15 Nov 2008

what would cause the hard drive not to spin up and the CD drives not to open when the 5v and 12V are present on the power connectors?

  morris948 19:18 15 Nov 2008

i decided to remove the cpu heatsink assy to see if there is anything amiss.
The heatsink came off with the cpu attached, so i cleaned it up and reseated in ZIF socket, rebuilt and system powered up all working OK.
Now i have learned that if there is no CPU activity, then the hard drive and CD' devices are inhibited from powering up, well, thats my theory..unless someone knows otherwise.
Thanks to all for moral support.

  woodchip 19:24 15 Nov 2008

Still sounds like faulty Power Supply to me. Try removing Data cable and power from Hard drive to see if it will power to BIOS

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