I cant get my pc to boot up at all, I switch on and all i get is the led and cpu, chas fan running

Try removing/disconnecting the hard drive and see if the BIOS boots up, if it does the HDD is causing the problem. Are you getting any beeping codes on start up, if so how many and hoe long in between?

It could be an overheating CPU problem.
When the CPU in the computer or laptopoverheats then it will shut down (i.e. thermal overload) and won't boot upagain until it has cooled down. If this is the problem is not fixed then theCPU will eventually fail.
A faulty fan causes this problem or the fan and heat sink assembly are cloggedwith dust.
Check the CPU fan to see if it spins freely, if not replace the fan. If the fan and heat sink is clogged withdust the remove the dust and make sure the vents are clear and dust free. Use acan of compressed air to do this.

Put just the ram back into the motherboard, the pc will not boot without processor, ram and graphics pluged into the board, check this, if it will still not boot and you still get 3 beeps its a memory(ram) problem, and you will need to replace the memory stick.

when you say cannot turn on cpu - what do you mean - ?
cannot boot up?
try removing the cmos battery for a minute then replace and try again.

any error beeps ?


working fine before ?

Replace cpu fan , failed cpu fan might have caused CPU stoped working. If you are sure about the CPU fails then replace the CPU. If the problem seems continues after that too, then PC might have failed to boot due to other reasons. What shows on the screen once you power on the computer? There could be , motherboard , or harddisk faults too. Try unplugging other parts and see if the computer boots from CD or USD flash or floppy drive!! Once you know that motherboard works then replace the CPU. There could be BIOS setup problem. Did you check the BIOS for harddisk is set properly.

First of all what exactly do you mean by "changed the CPU"? If its the processor? Is only the display not working, since you have said that the fan runs, it means the PC is starting. Check the Keyboard & mouse PS2 jacks. If there is any bent pins in the jacks? If so gently straighten with a pair of tweezers. Also try using a working Keyboard & Mouse from any other PC. If that still does not work, do you see the led lighting up on the MB? Does the MB make beeping sounds? How many? ALso mention the processor you have so that we may be able to help...............sodeep

Which fan are you referring to? As far as I know the fan in the power supply runs at the same speed at all times. So if that is the fan you are hearing it may indicate that the power supply is failing. The power supply may be over heating and shutting down. I would try a different power supply if you can get your hands on one.

you ight have a BAD CPU, try checking it out on another pc or friends pc.

May be your computer motherboard wires connection get loose or getting moisture in wires. Or there may be some earthing problem in ur power switch. First, check the wires connection & tighten up properly. if problem persists, check the earthing by power tester. Check you RAM if it is properly tight in the jack.

remove ram memory - it should beep when you switch it on - if no beep then check CPU in socket and cpu fan spinning when on.