I have an older computer the OS was XP Pro if that matters.  the last THING i did to it was take out the flopppy drive.  It was working fine but then all of a sudden it stopped booting up.  I also had the computer on for a while than i usually do, i had a fan problem in the past and replaced that i dont think the fan is bad again, but when i go to boot it up it seems like it starts booting up but then there is no signal to the monitor and i checked numerous times that everything is plugged in correctly and it is, is there something wrong with my motherboard?was it the heatsink fan.that was ..playing up?? or the psu...one...have you taken out ...or .disturbed the cpu  chip. for eg:...tell us what is happening when the pc boots.....like beeping etc.......Is all other hardware properly connected?

You should reset the CMOS if all hardware is properly connected.Older computer? When did you last check the CMOS BATTERY on the mainboard?I recently put in a new battery thinking thats what it could be but that did not help at all.  When it is booting up it does the initial beep but it then sometimes the lights stay on and then sometimes only one of them does, which usually means that it is going to boot up correctly, but either way there is still no signal to the monitor.  I nhave checked to see if all the hardware is plugged in correctly but i will check some more to make sure.  Is this on board video or is there a separate video card? Does the video MEMORY share the main RAM memory?

Have you run a diagnostic check on the RAM modules?