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I moved an old computer into a smaller case, switching out the motherboard, memory, power supply and cooling system. Now the computer tries to startup and restarts after 7 or 8 seconds. I tried running one stick of ram at a time, I tried hooking up the old power supply, and I moved the fan/water cooler to different fan controllers. I then started unplugging everything I didn't need to get to the bios ( harddrive, front panel usb, power and LEDs ). It doesn't matter whether the computer has been sitting all night or if I've been trying to get it running for 15 minutes; I'm therefore inclined to believe that it's not the CPU overheating, and I no longer think that it's a bad power supply. How can I determine if it's something wrong with the memory, motherboard or a damaged CPU?

Update: I purchased new memory and a new cpu but still no luck.

Update: I purchased a replacement motherboard, and that did the trick. I guess it was a faulty board.

System Details:

  • Motherboard: Intel DQ45EK Executive Series Q45 Mini-ITX DDR2 800 1333MHz FSB LGA775
  • cpu: Intel BX805573070 Xeon/3070/2.66GHz/4MB Cache/1066MHz
  • Memory: PNY Optima 2GB 240-Pin SDRAM DDR2 800 (PC2 6400)
  • Graphics: Intel Graphics
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Does it get into the OS? Are you sure no one is pranking you by placing a script to shutdown in your startup folder? That happened to me once. – danielcg Feb 16 '13 at 23:57
no, I don't see anything come up on the monitor. – 1_am_Jack Feb 17 '13 at 0:07
Are there any beeps? – terdon Feb 17 '13 at 0:10
Can you get to the BIOS? Does the "logo screen" (not sure what it is called) show? – BenjiWiebe Feb 17 '13 at 0:14
No beeps. There's a sort of click that occurs when the computer just starts up, and right before it shuts down. – 1_am_Jack Feb 17 '13 at 0:30
up vote 1 down vote accepted

Here's what I'd do:

  1. To boot a computer, you need the following things: CPU, motherboard, RAM, video, and power. Remove all other components. Everything else (and I do mean everything else) is superfluous to booting the computer.

  2. Make sure the memory is a brand and SKU listed in the motherboard manual. If it isn't, find some that is. Many motherboards are ridiculously picky about memory due to the performance constraints we place on it nowadays.

  3. Remove the motherboard from the case. It's possible the system board is grounding out to the case or the case switch is damaged. Make sure the motherboard is on a non-conducting surface before you power it on. If the motherboard doesn't have an on-board switch, you can use a screwdriver to make the contact on the switch header pins on the motherboard. To power the system off, maintain contact for 5 seconds. This seems scary, but it's the exact same thing the switch does.

  4. Examine the components to look for any burn marks, swollen capacitors, or funny acrid smells.

  5. Check your thermal grease on your CPU. This stuff is electrically conductive typically. Make sure none of it touches any pins on the CPU or socket.

  6. Start swapping components. Generally, I'd go in this order:

    • Memory

    • Video card (because I usually have a spare)

    • Power supply

    • Motherboard

    • CPU (these almost never fail outside of laptops)

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I've already tested with another power supply, and I just ordered another stick of memory and a cheap video card for testing. Hopefully it's one of those two things. – 1_am_Jack Feb 17 '13 at 22:47

As other's have noted, without further diagnostics, the only approach is to isolate each component.

That said, in my experience, this symptom (and I've seen precisely this presentation several times over the years) is always bad RAM. Especially if you can see it booting and loading OS, but then suddenly restarts.

Start with a new stick of memory. If that fails, go on to the other parts.

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Ok, I'll pick some up and see what happens. Thanks. – 1_am_Jack Feb 17 '13 at 5:32
Yes. Bad RAM, or incorrectly setup RAM (when I was updating my RAM, I got the dual channel slots in the wrong order, the computer hung for about seven seconds before rebooting). – Thomas Feb 17 '13 at 6:04

If you have a spare computer that your parts are compatible with I would attempt to put them in that. Judging by the fact that it will not get to BIOS and the fact that I am not physically there I'm forced to believe it is either a video or motherboard issue. Hope this helps but sadly I cannot comment on the question to gain more information so this is my best answer.

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