Computer won't turn on after installing new CPU cooler

By ihaveaname ยท 4 replies
Feb 18, 2011
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  1. Hey guys, I just installed a Noctua CPU cooler and now, once it's turned on, the fans start up but the monitor says "no signal" which I guess means it's not working (I have tried the monitor on another computer and it works fine so I know it's not that; same story with the graphics card and HDD). There is no BIOS. Also the HDD light pops on for about half a second after the computer is turned on but then it goes off.

    Any ideas on what's gone wrong? I get the feeling (vigorously) rubbing off the residual thermal compound on the CPU before adding the stuff that came with the cooler might have been a terrible idea but I didn't think that would destroy it?
  2. Mark56

    Mark56 TechSpot Paladin Posts: 1,886

    You should use alcohol to remove old thermal paste and that should come off fairly easily. I doubt if you have done much damage simply by rubbing it hard but what did you use.

    The most likely cause for this is that you have used a little too much compound and it has squeezed out and caused an electrical fault on the mobo. What make of paste did you use?

    You should remove the cooler unit and inspect and clean the entire area around the CPU, make sure there is no debris from the old or new paste left on the board, use a magnifying glass and bright light. You only need a layer of thermal paste no thicker than a layer of paint to do the job.

    The other problem maybe that you have disturbed a connection on any of the mobo connectors or the hard drive, pull off and reseat all the connections.
  3. ihaveaname

    ihaveaname TS Enthusiast Topic Starter Posts: 107

    The thermal compound came with the cooler, which is made by a brand called 'Noctua', which I hear good things about. Now I think about it I probably did use too much paste; so I should try to clean the area around the CPU with methylated spirits or the like? Will it be risky using that around the motherboard? And also, is it detrimental to the CPU if some of the original paste, which came with the CPU, was left behind? It is from a different company (CPU company; Intel) if that is in any way relevant.

    I have tried plugging and replugging everything so I don't think that's the problem.

    Thanks for the help! :)
  4. Mark56

    Mark56 TechSpot Paladin Posts: 1,886

    OK, hope it comes good for you. I would always use rubbing alcohol not meths, I've never seen meths recommended so I guess there is a reason for that. A layer of old paste should be cleaned off as it will reduce the thermal properties of the new layer of paste.

    As far as I know, thermal pastes are not usually electrically conductive but can be capacitive which will create problems if bridging across contacts.
  5. Tedster

    Tedster Techspot old timer..... Posts: 6,002   +15

    use a good cpu cleaning solvent to remove thermal grease. It is sold in electronics shops. DO NOT use household solvent. Then reapply the grease (a smidgen, centered on the die).

    Also ensure all your PSU connections are correct.

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