Troubleshooting my homebuilt PC overheating (no overclock)

Hello and thanks in advance for anyone who can help me figure out what's going wrong here.

The Short Version

Built the PC in January. No problems during winter but one warm day in April left PC on for at least 36 hours. Woke up, began to use it, it suddenly hard-rebooted and then I smelled smoke and powered it off.

Weather turned cool again and PC functioned with no problems or overheating (even after some Half-Life 2).

I kept the mobo monitor on all the time and when the weather warmed up and my office got stuffy again, avg idle CPU temp rose from 38C to 44C. What's more, mb temp rose to 45C or over. Monitor software warned me about motherboard temp, also that CPU fan was over 1000 RPM.

Again, please note: playing games (stressing the CPU) did not spike the temperature too, but ambient air temperature does seem to bump the average idle temp too high.

So what is going on?

Possible Mistakes I Made When Building It

This being my first build, it's possible I made a newbie mistake. I can think of two possible problems, but I don't want to create a misleading diagnosis, so take these with a grain of salt.

I used the in-the-box heatsink for the Core 2 Duo, but in addition to the thermal material that came stuck on to the heatsink, I added some thermal paste. I covered the whole heatsink surface with a thin layer. Probably too much, yes?

It's possible my wire management is bad. I tied up bundles of wires where I could, but the wires might be impeding air flow. Don't really know what I'm talking about here, though. Is it possible that this could be part of the problem?

Possible Conclusions

1. There really is something wrong with my system, possibly CPU or heatsink installation, possibly something else.

2. My system is OK actually, but it's not realistic to use today's powerful PCs in a non-air-conditioned, stuffy room. I need to suck it up and get an air conditioner.

3. 45C is an acceptable temperature for a mb, and I just need to up the max temp on my monitoring software, so it doesn't complain. On the other hand, my computer did reboot itself and emit a smoke smell that first morning.

4. Something else?

Relevant Components

Intel Core 2 Duo E6400, with Intel heatsink, and (maybe too much?) extra thermal paste.

ASUS P5W DH DELUXE motherboard

COOLER MASTER Centurion 5 CAC-T05-UW Black Aluminum Bezel, SECC ATX Mid Tower Computer Case

FSP Group (Fortron Source) AX450-PN, 12cm FAN, version 2.2, 2 SATA, PCI Express, 450W Power Supply

CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model TWIN2X2048-6400
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More about troubleshooting homebuilt overheating overclock
  1. Check the heatsink for dust, if that's clean try running the system with sidepanel of and see if that helps. You could always try to clean the heatsink and re-apply (sparingly :D ) thermal paste. Too much is never a good thing. Also.. try to put up a pic of the inside of your case for wise people to judge your airflow. Maybe you have a hot chipset on the ASUS board but have no experience with that board.
    Really, try cleaning your system first. Depending on how dusty your office gets 5 months is plenty time for dust gathering.

  2. I'll second the fact that too much heatsink paste is not good, clean it all off and reapply.
  3. At the risk of sounding naive, how much paste is too much? How can you tell?

    Also, was it a dumb idea to add the paste in addition to the (non-paste-like) thermal material that was already in place?
  4. Try turning off CPU fan speed control in the bios. The fan will always run at full speed. It'll cool better, but be louder.
  5. Basiscally it all depends on how flat both your CPU and the heatsink are. All the thermal paste needs to do is fill any areas that don't connect, so you really need a very small amount. Theoretically, if these surfaces were perfect you wouldn't even need the paste. Some apply a stripe of compound in the centre of the CPU and rely on heatsink pressure to smear the paste. I usually just spread a VERY thin layer with my finger across the entire surface and remount the heatsink. It has always worked for me. It all depends on your personal experience I guess.

  6. And it's really ok to use your finger, and not a credit card or something? What about the skin oil?
  7. Wash your hands and don't sweat :D
  8. Quote:
    And it's really ok to use your finger, and not a credit card or something? What about the skin oil?

    Put your hand inside a plastic bag, then use your finger with the plastic covering it.
  9. Are both the case fans spinning? Have you cleanes the front filter? Heatsink gives a heat difference between the CPU and the air temp in case. If case temp rises by 5C, then cpu will rise by 5C.

  10. don't use regular rubbing alcohol 60-70%

    wipe with something plastic {lego perhaps?}
    the idea is to not scratch the surface

    use +90% or greater isoprophyl alcohol


    Arctic Silver Arcti-Clean

    on a microfiber lens cloth

    finish off with a dry microfiber lens cloth


    read the actual instructions to thermal grease
    put a small dab in the center of the heat sink {like a grain of rice}

    thermal compound is a nook & cranny filler, ideally you would want the heatsink fused to the processor so there would be maximum thermal conductivity.

    to much thermal compound acts as an insulator.

    you can't always tell were you system is getting its thermal reading as well be careful.

    when My heatsink bracket broke, it went unnoticed the first couple of times I opened my case; the thermal trip in the processor would go off, and the video would freeze.

    I would use Arctic Silver for the thermal paste / compound

    20°C room temp is the best {it's what most stuff is designed to work at
    with proper equipment you could go as high as 35°C, it might be cheaper than a room air conditioner
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