my pc wont start ,as soon as i press the button to boot it up it just shuts down, dosnt even get chance to boot up , ive put another power supply in and still dose the same, ive been told it could be a earthing problem but dont know were to start

Is this a new problem? Were things working OK previously? Any new hardware?

Are you sure that the power switch is not sticking? This would shut it down after 3 seconds.

Originally Posted by jephree

Is this a new problem? Were things working OK previously? Any new hardware?

Are you sure that the power switch is not sticking? This would shut it down after 3 seconds.

it started about a couple of weeks ago , it would run for about 15/20 min and just shut down . now it dose it straight away, added another hard drive never had any problems but that was months ago , have tryed 3 diffirent psu but still dose the same

I would try moving the RAM. If you have multiple sticks just use one in slot one. If that doesn't change anything try different sticks in slot one.

Run with the case open. Check your fans. Feel the air around the CPU for extreme heat.

Does the motherboard have a power LED? Is it on?

Originally Posted by jephree

I would try moving the RAM. If you have multiple sticks just use one in slot one. If that doesn't change anything try different sticks in slot one.

Run with the case open. Check your fans. Feel the air around the CPU for extreme heat.

Does the motherboard have a power LED? Is it on?

led on motherboard comes on and stays on, have removed ram and replaced, checked reset switch, the cpu dose not get a chance to get hot

Perhaps your processor has gasped its last breath. Just throwing out a thought here.

Check the CPU heatsink for dust, tightness. Same for the CPU fan. As well it should be spinning ~pretty fast~. It takes literally just seconds to overheat if there's a cooling problem. A dusty therefore slow running fan will eventually cause an overheat state. If cooling is/was the case, it (the CPU) may have already cooked as CaptainMazda eluded to.

Are you getting any "out of the ordinary" POST beep codes?

no ,no beep codes will check cpu