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Not booting (Or reaching POST)

by llam4 / February 9, 2008 2:35 AM PST

Hello all, I recently bought my own parts to build a computer. I have done this before with much success. This time, however, I am unable to boot up. The first two times this computer was run, it got to the POST splash screen and turned off. Now my fans just spin when I turn it on.

My HDD light blinks once and then I don't get either green nor orange lights on the front of my computer. I don't get a BIOS beep (Yes my speaker is plugged in correctly). I hear my hard drive power up, my video card fan spins, my CPU fan spins... I've even replaced my motherboard, with the same result.

Right now I'm using the ASUS M2N-E ATX Motherboard, the nVidia 8800GT video card, a 3.2GHz dual core 6400+ AMD processor, one 80GB ExcelStor SATA hard drive and 2x 1gb 800MHz Corsair DDR2 RAM. My PSU is an ATX12V Zephyr 750 (750W with a good amount of strong rails).

If I strip down my motherboard to nothing but a single fan, I get the same problem. No beeps (Should get beeps with no CPU...). If I don't plug in anything, including fans, the motherboard/CPU only stay on for half a second.

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Just sharing.
by R. Proffitt Forum moderator / February 9, 2008 2:55 AM PST

I had one do that. I had put an incompatible CPU in the board. While socket 775s do come in dual core, my board didn't support that. Power up, and then a few seconds later, power off.

Dummy me for not checking that list.

http://support.asus.com/cpusupport/cpusupport.aspx?SLanguage=en-us&model=M2N-E notes your CPU but I see it has OTHER REQUIRES such as motherboard rev or BIOS versions. Check it again?


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Matches up
by llam4 / February 9, 2008 3:09 AM PST
In reply to: Just sharing.

Everything matches up. I don't understand how I'd flash the BIOS since I can't even reach POST, though.

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I hate that one.
by R. Proffitt Forum moderator / February 9, 2008 3:13 AM PST
In reply to: Matches up

You don't want to know I had to install an older supported CPU to get the board to boot up so I could install the BIOS that gave my board support for the newer CPU.

Since you can't boot the board you can't check the BIOS rev...

Next time, buy a motherboard+CPU bundle.

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Might not even be the CPU
by llam4 / February 9, 2008 3:21 AM PST
In reply to: I hate that one.

At this point I'm not convinced it's the CPU. The problem is prevalent even when nothing is plugged into the motherboard, CPU included. I've already replace the motherboard, so it seems like either two bad motherboards or one bad PSU. The PSU powers everything, though... I have no idea what could be wrong.

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Did I miss it?
by R. Proffitt Forum moderator / February 9, 2008 3:26 AM PST

What PSU? And you don't have a spare? Almost any will do even in the 200 Watt range since no video, hard disks, etc.

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From original post
by llam4 / February 9, 2008 4:10 AM PST
In reply to: Did I miss it?

My PSU is an ATX12V Zephyr 750 (750W with a good amount of strong rails).

The mobo takes a 24-pin connector. I'm not sure if this 3-year-old psu will power this mobo but I'll try it when I can.

On another note, this PSU uses a 20 + 4 connector (2 connectors) and I see no change in response when I remove the +4 than when I have it plugged in.

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"a good amount of strong rails"
by R. Proffitt Forum moderator / February 9, 2008 4:17 AM PST
In reply to: From original post
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Shorting it works
by llam4 / February 9, 2008 4:38 AM PST

Shorting the two pins spins my fan. Plugging it in to my motherboard and hitting the on button does not.

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That proves something.
by R. Proffitt Forum moderator / February 9, 2008 4:43 AM PST
In reply to: Shorting it works

The motherboard doesn't keep the PSU on...

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Yeah, but...
by llam4 / February 9, 2008 4:52 AM PST
In reply to: That proves something.

Would that mean it's the motherboard or PSU? I've already replaced the motherboard, it's done this with both.

Also, I'm finding out now that even with a CPU, memory and a hard drive attached to the motherboard, the PSU doesn't stay on for more than half a second. In order for it to stay on, I need to plug in a fan. Either of my chassis fans, the cpu fan or the video card's stock fan will keep my system running if they're plugged in. If none are plugged in, I get nothing.

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Plugged in 200W
by llam4 / February 9, 2008 5:19 AM PST
In reply to: Yeah, but...

Plugged in the 200W. It managed to stay on where the 750W is failing. Man, I really didn't want to replace this PSU. Looks like that's the problem, though.

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Ahh, that's very telling.
by R. Proffitt Forum moderator / February 9, 2008 5:22 AM PST
In reply to: Plugged in 200W

You learned the PWR ON signal, but there is a power good signal that didn't work...

Great sleuthing on your part.


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by llam4 / February 9, 2008 5:33 AM PST
In reply to: Plugged in 200W

Thanks for the help, Bob.

Have to reply here because of thread depth.

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Not the PSU
by llam4 / February 9, 2008 8:34 AM PST

I just bought a new PSU. Different brand, 650w. Same exact problem. I also had the same problem with the previous motherboard.

What the hell!?

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Does the 200W continue to work?
by R. Proffitt Forum moderator / February 9, 2008 11:55 AM PST
In reply to: Not the PSU

That's barely enough but enough to power the CPU and motherboard to hear some beeps. I have an old 5 watt PCI video card for such testing. Anything in the closet?


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by llam4 / February 9, 2008 12:10 PM PST

I don't have any old desktop hardware (This is a laptop). And the 200w wouldn't hold my vid card + memory + cpu + hard drive long enough to see a post screen. My motherboard has no onboard video, or it may have been plausible.

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by R. Proffitt Forum moderator / February 9, 2008 12:19 PM PST
In reply to: Nope

Yes. Build it on cardboard. If it doesn't work there then it's not a case mounting issue.

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Done that
by llam4 / February 9, 2008 12:43 PM PST
In reply to: Ok. REMOVE THE CASE.

Done that Happy

What is supposed to happen when you run the board with no CPU? Is it anything like what's happening to me?

I'm thinking my CPU may have been DOA.

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What happens.
by R. Proffitt Forum moderator / February 10, 2008 1:54 AM PST
In reply to: Done that

Is not an assured thing. On old boards I'd write the power comes on but nothing else interesting. Today with the possibility that the empty CPU socket can create odd logic signals a safe thing to design in would be to power down after detecting "No CPU."


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Might double check the MB, BIOS and CPU ... the BIOS
by VAPCMD / February 9, 2008 9:38 AM PST

on the MB may not be compatible or new enough to support the CPU installed. Assuming the CPU and MB are both good...the only way around it is to buy a CPU compatible with the oldest version of the BIOS for that MB. All you need to do is install it, flash it and replace it with the new CPU.

Let us know.


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by pvc_ / February 9, 2008 1:18 PM PST

not sure if this would make a huge difference in your case, but try to loosen the screws on the mobo.

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Go to the shop
by Nataku4ca / February 11, 2008 7:38 AM PST

I think the best thing to do is bring the computer into a shop that u bought the parts from and ask if you could "borrow" an old CPU to turn on the computer for flashing the BIOS.(assuming thats the problem)

btw, if your mobo uses voice instead of beep for errors you might not hear anything from the internal speaker, instead you need actual speakers. of course im guessing Silly since mine is like that, won't beep for error only with speakers.

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