New Computer won't POST just Reboots after few seconds

[jamesx007]

Hi, I am not sure if this is the right place to ask - since I am new to the forum. Please forgive me if I posted to the wrong place.

I just recently built a i7 950 System with Gigabyte GA-EX58-UD3R board and 3gigx3 Tri channel memory.

The computer booted up just ONCE. That was barebone. I have yet to connect the chasis fan. But the CPU Cooler and Graphic Card is all plugged in, and it booted.

So I took off the cords and plug in the chasis fans (like the front HD Fan, the Side Panel Fan, and the Back Fan).

Moved it to my computer table (Was assembling on the floor).

Then plugged it back in.

Now it powers up. All the LEDs lit up, the Graphic Card fan starts, the Graphic Card LED lights up.

But before it boots, in about 2-3 seconds, it powers down. Then restarts, then powers down, then restarts.

I have no idea what is wrong - going to buy another PSU when I get off work today. Hopefully that is the problem.

Does anyone here solved a similar situation?

 

[shortstuff_mt]

This problem is so common that a sticky was created to help with troubleshooting it. You need to go through every step in this checklist.

http://www.tomshardware.com/forum/261145-31-read-posting-boot-problems

 

[xbonez]

the only thing that comes to mind is, is you power supply being overloaded?

 

[jamesx007]

Just read the Check List and I already exhausted those steps on my own checking.

I don't think it is overloaded since it is a 750 PSU designed for SLI/Crossfire and I am only using 1 video card.

The Weird thing is it booted once. After it stopped booting, I removed all the connectors to the new fans that I plugged on and it still didn't sucessfully boot.

I took out all the ram and tried 4 new sticks (one at a time) and looping reboot still happens.

I took out the video card just to see if it still boots like that, and it still does.

When I first was assembling the computer I accidently step on the 8 pin power plug (very lightly, there is no visible damage as far as I can tell, and it plugged into the motherbord socket fine). The computer booted up normally - the only time it did.

Just in case the plug is damaged, I am going to exchange the PSU for a new one and see if that fixes if. If not, I am completely at a loss.

 

[jamesx007]

k.

I switched out the PSU and it still does the constant restart cycle.

So I unplugged everything. Memory, CPU, Graphic Card, everything.

Try to turn it on it still restarts constantly.

I am at my wits end. Anyone know anything?

 

[jsc]

Strip everything out of the case and breadboard the system. It will look something like this:
http://www.tomshardware.co.uk/forum/page-262730_13_0.html
You can turn on the PC by shorting the two pins that the case power switch goes on.
Make sure you have a case speaker connected.

 

[jamesx007]

I have the little connector Speaker that came with the case. It is plugged in.

I don't have any drives or the Video card or even memory.

I only have the CPU and the Heat Sink installed.

I used the screwdriver to turn on the board. The lights come up, the fan starts to spin, then it turns off and restarts.

This will keep looping till I turn off the power.

I have no idea what is wrong. It is doubly confusing that it sucessfully booted once, then this happened.

I don't smell any burnt plastic either.

 

[jamesx007]

I am using the Akasa Nero (Ak-967) Heat Sink for the Build.

The Heat Sink and the Case is the only 2 common component between the 2 builds.

I double checked the case, there is no extra stand-offs and no wires that would have sorted the board.

So the only mystery component is the Heatsink.

I thought the heat sink felt a bit tight when I pressed the push-pins in and the new LGA 1366 sockets are so fragile.

Is it possible that the Heatsink is too tight and it bent the pins in the socket?

Or that is next to impossible?

Guess I'll find out today when I try to exchange the board and CPU again.

 

[jsc]

Your problem may be the PSU. What kind do you have?

 

[jamesx007]

I am using the Antec EarthWatt 750

http://www.antec.com/Believe_it/product.php?id=NzI4

It was my 1st Suspect after I exchanged the MB and CPU and still didn't work.

So I went back and exchanged the PSU. Even with the brand new PSU the continuous restart problem persisted.

Antec is also a very good PSU Company (I think) so I don't think it is because the voltage is insufficient.

 

[jamesx007]

The Computer Works now.

It was the Motherboard that was bad.

I guess I just got the incredibly unlikely "2 brand new motherboard in a row that is bad" problem.

The Third one is the Charm. Exchanged it, kept everything else the same - Case, CPU, Heatsink, Memory, Drives, etc. The computer booted up finally.

 

[Paulo Pegado]

I'm having the exact problem you had 6 years ago. The difference is that I'm not building a new computer, instead I only opened it to add two hard drives.

I also unpluged everything and I'm turning the computer with a screwdriver. It turns on, and restarts after a few seconds. I guess I did something to break my mother board.