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I've just built a new PC and I'm having problems when starting up for the first time:

  1. I get no video
  2. The system powers on for several seconds, then powers off for a few seconds before powering on again and remaining on (there is no video output at any stage)

The CPU fan is spinning freely, as are the case fans so it's not overheating. The mobo green light remains on.

I've tried unplugging the HD and CD player from their SATA connections but no change. I don't believe the case has a speaker so I'm not hearing any beeps. Also I've tried removing 1 of the 2 strips of RAM, and then all the RAM. In both cases I get the same behavior described above in point 2.

System specs:

  • Mobo: Asus P5Q-EM
  • CPU: Intel 6300
  • RAM: 4GB DDR2
  • No GPU card (on-board graphics only)
  • No other cards attached

Do I have a component failure?

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up vote 1 down vote accepted

You might want to check if the motherboard needs two power connections and if so both are connected properly, sometimes there is a second smaller 4 way connector near the CPU.

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Thanks for this tip, I feel like an idiot now! – Jonny Aug 29 '09 at 2:36
I did this exact same thing when I built my computer. – Dan Walker Aug 29 '09 at 3:17
@Jonny: The only reason I knew that one is that I fell for it myself a while back :-) – Col Aug 29 '09 at 6:29

That's exactly what it sounds like. The no video isn't as concerning as the machine shutting itself down. It's either the CPU or mobo, and in my experience, I'm always suspicious about the motherboard first.

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As I was reading this, I immately suspected the RAM, but it's clearly not that due to the steps you've taken. I can't think of a jumper setting that could cause this, but is there any chance you've moved any jumpers around? – Jeffrey Aug 28 '09 at 15:17
It would be an interesting test to try to start with the CPU removed from the system. If the behavior is the same, then it's clear that the motherboard doesn't even know the CPU is present. If it's different, then a faulty CPU or faulty motherboard could cause it, and tell you nothing new. – Jeffrey Aug 28 '09 at 15:24
I tried your suggestion of booting up with no CPU and I don't see the strange restart behavior. With the CPU back in place it's no longer booting at all. – Jonny Aug 28 '09 at 23:29
Bummer. There's definitely a chance it's just the CPU, but that little test can't tell you anything definitively. – Jeffrey Aug 29 '09 at 0:28
Thanks for your help but it turned out to be a simple problem as per the answer I picked :) – Jonny Aug 29 '09 at 2:35

Probably motherboard. If I were you I'd try to find case speakers. It can provide some valuable informations. If it's new you still have the varanty so go for it and return a PC to the seller.

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This does sound like motherboard or cpu failure. Depending on where you got your components from and whether there in warranty, you may consider sending both back. Otherwise, invest in a pci post reader. That will give you a good idea of how far into the boot process you're getting and when things are going wrong.

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I would bet on it being a motherboard issue, but it could be a CPU issue, or even power supply issue. If you want to get to the bottom of it, as above, get a PCI POST reader and a power supply tester.

If you can, try to get a PC speaker hooked up to it so you can hear the beeps and try to diagnose from there. I would also get a plug-in video card (even PCI will do) to see if there's an issue with the on-board graphics.

Other than this, I would say test the power supply with another computer or power supply tester, and, likely, get the mobo and possibly CPU replaced.

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