Motherboard problem?

Ok, here's the problem. I am running xp on a clone system and had problems in the past with my computer shutting down intermittently. I figured it was a heat problem so I removed the heatsink and reseated it with AS5. I also added 2 case fans as it only came with the hsf. After doing all that it ran great for about 2 months with no shutdowns. The other day I was working in Word and my mouse started acting funny. Right click started functioning as left click and I couldn't get it to act right so I restarted my computer. After powering down, It didn't power back up. Thinking it was the power supply, I picked up a new one at a local computer shop and swapped it out. Still no boot up. I reseated the ram and no boot up. I pulled out all cards except video card and tried to boot but still didn't post. Green LED is lit on mobo when power is applied but nothing happens when I power on. I got the hsf to run once but still didn't get a post. I'm guessing that it's the mobo now and I'm just hoping someone out there may have some insight into my problem before I drop some cash on a new one. Any advice would be greatly appreciated. Thanks in advance.

It sounds like a motherboard may be in order. It is possible you just lost the BIOS. I think that before buying a new board you might try recovering the BIOS. If you have an intel board you should be able to find a jumper on it labeled Recover/Normal. Jump it to recover. Find a BIOS for your board on the Intel site and put it on a floppy. Put the floppy in the drive and boot the computer. You will not get any monitor activity but you should hear some beeps on the system speaker and see the floppy drive light active. Let it run for awhile. When you hear two beeps and the floppy light goes off and stays off, wait another full minute to make sure the reflash is done, then power the system off and put the jumper back in the normal position. If that doesn't work then it is most likely time to go mb shopping.

Well… I'm almost sure you're right about it being the motherboard. I don't think it's the bios. If the computer powers up the hsf should at least turn and it isn't. Nothing happens when I press the power on switch. Like i said… all I get is a green LED on the mobo when the psu switch is on. I press power on and nothing happens at all… I did get the hsf to turn for a few seconds once… but i had all drives removed and nothing but the mobo powered up. Thought the problem was fixed, so i powered down to hook up the hdd, tried again and nothing happened. No fan movement or anything. So unless you can think of anything else, it's off to the mobo store. Thanks for your reply

Unplug your other boards one at a time, trying to power on after each one. When you see the fan move then reconnect every other one except the one you removed just before the fan started. If there is one device that is drawing too much power (short circuit) this could keep things from working and may damage a new motherboard. On the other hand if there is a weak circuit in the motherboard it may fail under normal load but as you disconnect devices and reduce the load then the circuit may work. Good luck

Are your drives spining up? Check and make sure the CMOS reset jumper hasnt completly fallen off its pins. Make sure CMOS itself is good.. Curious to know though if your drives are spinning up

That would be great.. if I was asking about "fans or anything". However I was not. You might be able to hear them spin up but you will deffinately be able to feel them do it. Also.. Have you checked the fan to make sure it works.. because that will most DEFF. cause that to happen.

Strip the system to bare minimum and clear cmos. This means nothing but the video, 1 trusted ram dim and cpu. If you get to the no os installed error you know the mobo is good. Look for blown caps or a burnt smell.. Test cpu in other system if possible Remove mobo from case and layout on cardboard or newspaper incase their is a short and strech the psu to the mobo with no usb etc..