my machine keeps shutting down just after i turn on it is not even booting windows and it also looks like there may be a fault with graphics card i cannot get it to stay on long enough to do any diagnostics

Maybe over heating.

Please open your case and see if the Heatsink is secure.

Are you/Did you hear(ing) any beeps when you did/were boot(ing)?

Single short beep means everything is fine.

Its when you hear multiple beeps that you have a problem.

Can you remove the Ram and boot?

my machine keeps shutting down just after i turn on it is not even booting windows and it also looks like there may be a fault with graphics card i cannot get it to stay on long enough to do any diagnostics

Do you have a spare power supply that you could try. If it isn't getting enough power, it may do what yours is doing. I would at least rule it out.

Do you have a spare power supply that you could try. If it isn't getting enough power, it may do what yours is doing. I would at least rule it out.

The possibility is rather rare, but it doesn't harm to rule it out.

cannot boot without ram still just turns off stuck in new ram stayed on a bit longer but then off again tested psu working ok and tried a diff one on machine no difference

did you hear any beeps without ram?

no beeps at startup, heatsink is fine

remove heatsink, clean old paste from cpu and apply new paste,also check heatsink of onboard chipset and video card chipset , do the same if possible

as i suggested ,replace paste even if you need to go buy some ,and do it to all hs,do you have onboard video or is it a addin video card ,or maybe you have both a lot of board do ,if you have both,remove the addin and try the onboard video .

as you say in first post ,maybe its a dead motheboard

machine came on a few mins ago and stayed on longer than before then screen went wonky like as if graphics card was gone then shutdown again

Look for the GPU chip touch it when you boot does it get really hot really fast?