Ok, don't panic! (Well, not yet anyway...)
Can you try these things in the following order please:
1) Disconnect the power cord from the back of the computer. Also disconnect any USB devices you may have. (If you have a USB keyboard, then leave this plugged in)
2) Open up the computer - wherever you position the computer, please make sure it's not on a carpeted surface. Discharge your own static by touching a metal surface with one hand (a radiator is good).
3) Disconnect the main power cable that connects the PSU to the motherboard. This will be the big white plastic 20 pin plug.
4) Disconnect the hard drive cabling from the motherboard (IDE & SATA). Disconnect the cdrom cabling from the motherboard (note you can leave the ribbon cable plugged into the drives themselves, just disconnect the motherboard end). Disconnect the power from all hard drive but leave power connected to the cdrom drive. Leave the floppy drive connected up as usual.
5) Remove any PCI cards you may have. Leave only the AGP video card in place. Make sure the AGP card is securely in it's slot.
6) Locate the round silver battery on the motherboard (looks like a coin). The bunch of wires that plug into the board nearest this battery are the front panel connectors. You should see something like this (make sure you are looking at the board so that these wires are to the right of the battery, as shown below)----- - - ----
o [o o][o o](BATTERY) [o o][o o]
[o o] represents a single connector with 2 wires. The pair in blue are for the front power switch. Make sure this connector is securely connected. (It makes no difference which way round it goes providing it's covering the 2 pins shown in the diagram.
7) Next reconnect the main PSU (internal) power cable to the motherboard. Also check to ensure that the 4 wire (2 yellow, 2 white) square connector is connected to the board. This connector is close to the processor. NB Both of these 2 power cables are keyed so they only fit one way round so don't force them!
8) Make sure you have the monitor cable plugged in to the back of the computer, then reconnect the mains power lead to the rear of the PSU & power the system on. Make a note of any beeps you hear & of what happens (i.e is there a picture on the screen etc). If the computer stays powered up for long enough to check, then make sure that the fan on top of the CPU is spinning.
Power the system off when you're ready & let me know what happened.
Edited by Samm, 20 November 2007 - 05:37 PM.