Need a bit of help please

Clarifications

the CPU came off with it? Had you released the retention bar?

I have seen this happen before. The CPU may have bent pins. Verify it's integrity.

Another issue may be the thermal compound. Clean off all the old stuff and apply a small amount of compund to the CPU. Gently spread it around to barly cover the metal top. Reconnect your heat sink.

If none of that corrects the issue, unplug your floppy, try to boot (you may get an error). Then re-attach the floppy cable (try it the other way around).

1). Make sure the processor and heat sink are ok. Meaning, take them out and give them a good clean and apply a very very small amount of Thermal paste then re-seat the heat sink and fan.
2). Graphic card. Take it out, switch on your computer, you might hear a few beeps. Switch off your computer, re-seat the graphic card.
While doing all of this make sure you are grounded at ALL TIMES by placing your hands on the metal parts of the case.
3). Make sure you have ALL of the power cables plugged in.
4). Power up your computer, get into the bios and select "load default settings", Then "save and exit", this will save your settings and re-boot your computer of which you will get to see your desktop again.

Please post back if you have any more problems or questions.
If this information is useful, please mark as helpful. Thanks.

Was there two connectors for the CPU heat sink or one with three wires? The problem sounds like the system is not booting because you have a broken wire on the heat sensor mounted on the CPU heatsink. Either one connector didn't get plugged in if it has tow, or the three wire connector has a broken wire/pin or the connector didn't get plugged in correctly. This will stop the whole system from starting.

The Data Leads to the Floppy, HDD, Optical Drive are Polarized Leads meaning that they need to go on a certain way and if there was more than 1 IDE Lead for the Optical Drive and HDD then the correct lead needs to be fitted to the HDD and CD ROM.

Secondly how did you clean out the dust?

If you used one of the Static Type Dusters this will have destroyed the M'Board as they generate Static Electricity to attract dust. Static Electricity is something that must be kept away from Electronic Components and devices at all costs.

Now assuming that the CPU has no bent pins and is correctly fitted the Data leads for the HDD has a Red Trace along one edge this needs to be closest to the Power Connector on the HDD. The same applies to the CD ROM as well here. If there are 2 Data Leads one for the HDD and one for the CD ROM then the one with the smaller wires and 80 Wires needs to be attached to the HDD and the one with the thicker Wires and only 40 wires needs to be connected to the CD ROM.

The Red Trace needs to be fitted closest to the Number 1 Pin of the socket on the M'Board for both of these leads if you have 2. Also the Floppy Drive lead needs to be inserted to the M'Board the same way with the red trace closest to Pin 1. All of these Sockets should be oriented the same way here so Pin 1 is at the same end on every socket.

As for the Data Lead it needs to have the Red Trace closest to the Number 1 Pin on the header Strip on the Floppy Drive this should be marked with either a small Circle or Triangle stamped into the Floppy's Metal Case.

Cleaning out Computer cases is a necessary job as they attract dust and other gunk like there is no tomorrow but you shouldn't be pulling them apart Use Canned Air to Blow out the accumulated junk inside the case but make sure that you prevent any Fans from Spinning as they will generate Electricity and damage the M'Board.

If you can not access Canned Air very low Pressure Compressed Air will do the same job and save you the need to dismantle. This will also clean out Dust Blockages on the CPU's Heat Sink and while you are at it look at the Heat Sink on the Video Card as these quite often have a Fan on them as well and need cleaning out.

If you only have the One Data Lead for the HDD and Optical Drive it needs to be inserted into the Primary IDE Socket on the M'Board this should be the one closest to the edge of the M'Board.

Col