freezing & power off

[meg]

Hi i hope someone can advise. I have problems with a lenovo G555 laptop which started slowing down over the last few weeks then sporadically freezing and powering off with or without freezing first. It was running windows7 and had up to date antivirus software. It now will only work for about 10 mins before freezing or powering off

I tried a system check but it froze before completion. I fitted a new hard drive yesterday but it powered off before the windows installation was complete, it does this with or without the power supply attached so i dont think the problem lies with the power pack. The ram sticks have been changed and the same happens so i dont think the problem is memory related and it cant be software either now. Can anyone suggest what to look at next?

[Salmon Trout]

I would certainly consider overheating as a possible issue.

[meg]

Ive taken it apart and cleaned out the fan. fan is working fine. Turned back on with the new hard drive in but it came up error reading disc with the windows disc in and wouldnt load it - it was reading it fine yesterday. So iv put the original hard drive back in and it started to run check disc again but has frozen at 13%. The previous two times running check disc on this hard drive it froze at the exact same place 13%.

Dont know what to do next... iv eliminated software, ram, hard drive, power supply & fan

[Salmon Trout]

Why are you so sure it's not RAM related? You changed the sticks, you say. With what? Brand new compatible RAM? If so, maybe the memory controller (or some other component) on the motherboard is flaky. Is this machine still under warranty?