new build power loop at boot no POST or beeps - new cpu, motherboard and PS

Posted on 2011-09-12
Last Modified: 2012-05-12

I have just made a new build, new power supply, new case, new motherboard (gigabyte Z68MA-D2h-B2), new cpu (intel i3 2100) will not go into BIOS or do anthing at all! When I press the power button, I simply get to see everything light on, then turn off with in 2-3 seconds and then repeat that oover and over again. Here is what I have tried:

I replaced the new motherboard for another new motherboard, tried to boot wih nothing pluged in, tried different ram, no ram, only one stick of ram, tried to boot outside the case (sat the motherboard in the anti-static wrapt it came in so I would see if maybe it was a short with the case touching the motherboard, I tried a different power supply (known good one) I tried adding a fan ( the case comes with one but does not plug into the board) the one that I tried is a small fan with 3 pin holes only, leaving one open (IDK if thats a problem) . I have the 2 ATX power cables plugged in (one large one and one 4 hole one in the same ATX socket in addition to the regular 4 hole 12 v that stands alone on the other side of the board) i have tried an PCI video card and plugged my monitor in there just incase I can see something in the screen thru it. Again, no video, no beeps, no antying expect everything turns on, then off and loops until I unplug it from the power supply. The power button does not do anythhing except turn it on, I cant use it to turn it off or stop the power loop. The only cable plugged in from the case is the power button.

Question by:kaosmadness
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Expert Comment

by:Mohammed Rahman
ID: 36525843
As you have already replaced the Motherbeard and the PSU with no positive solution. Try, remove the heatsink from the processor, turn ON the computer (be ready to turn it OFF quick), place the finger on the CPU and notice if it heats. If its heating its good. If its not, you may have a bad CPU. Also the power button on the cabinet could be faulty. Try turn ON the computer by shorting the two PINS to which the power button cable connects. You can use a screwdriver or any conductor and just touch the two PINS and that will turn the device ON. Its possible that the power button is stuck and it might be turning OFF the computer in 2 - 3 seconds (very less chances).

For now, lets imagine the power PINS on your MOBO are same as in the PIC below (link).

You have to take a metal conductor and touch the two pins for a second. (like the black PW_ON in the picture)

Author Comment

ID: 36525920
Thanks, But I did replace the CPU which was brand new fromt the start but it was changed anyway. It doesent come with a heatsink but a cooler with thermal paste. I added a little more just in case. Same result. Should I purchase a heat sink instaed of the cooler it came with? I will try shorting out the power pins.

Thanks again!

Author Comment

ID: 36525978
No, same result when I short the power pins... It powers up and then shutsdown, goes into a loop but never any video, beeps, or sign or processing. The monitor light does not even change to green. I noticed, and I am more of  software guy not hardware so maybe its nothing, that the ATX power cable has two parts to it (the last 4 pin block can be removed or pluged in along with the other big part) should I be using those last for pins in the 12v motherboard input? also the ATX big power cable, seems to be missing a cable (one pin not present nor cable) but the motherboard does have a pin for it. On the other power supply I tried, it also had holes with no cables but different ones. The motherboard instructions say that it is recommended that I use a 500 watt PS (does say you have to but that doing so may cause stability problems) since i dont have a hard drive plugged in or anything, do you think this could be because the power supply I am using is 480 watt max? The other power supply I used had the exact same issue but it is a 500 watt max PS. When they mean 500 watt, should be looking at the MAX or at the average watts?

Thank you soooo much!!!
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Accepted Solution

Mohammed Rahman earned 500 total points
ID: 36526539
PSU should not be a problem here. A 480 and 500 is more than sufficient to drive your unit.

** You have replaced the CPU, motherboard, PSU with known good ones.
** No hard drives and optical drives connected.
** Tried different ram, no ram, only one stick of ram, tried to boot outside the case.
I dont think it to be a RAM causing the issue. If it would have been RAM, the system will not have display, may have beeps and may not. But, the computer will stay ON and not keep restarting every 3 seconds.

2 PSUs, 2 CPUs, 2 MOBOs going bad (unusual). Try connecting to power supply to different wall socket (AC Mains). Also, the thermal paste should be a thin layer.

Incorrect way of applying thermal paste:

Correct Way of applying thermal paste: (apply the paste in centre and place the cooler/heatsink on the CPU. Make sure that coller/heatsink locks on MOBO.

Try remove the CMOS battery and short the CLR-CMOS for 5 seconds and then start the computer.

Its not possible that a keyboard can be causing the isue. Nevertheless, try to turn it ON with out connecting the keyboard.

** I think it to be a problem with the Processor. It might not be seated properly, or there might be a gap between the processor and the cooler, making the CPU hot and restarting every 3 seconds.

Did you place the finger tip on the processor, not the cooler and feel it hot (warm) ? Does the small heatsink near the SATA connections heat up ?
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Expert Comment

by:Mohammed Rahman
ID: 36526571
If there is any problem with the 12v 4 pin (2 yellow/2black) cable, the computer will turn ON with no display.
If the problem is with RAM, the computer will still turn ON with beeps or without beeps and no display.
If its a problem with the video card, the computer should still boot and remain ON with no display.

A faulty PSU could be causing this issue, but again, two PSUs ... dont think so :(
Faulty MOBO could be the issue, again, two MOBOs... very less chances.
CPU could be the very reason for restart loop. You say, you have changed that too...

Try remove the CPU and analyse the pins on the MOBO very carfully (should not have even 1 pin bend and it should be 100% dust free. Gently clean the CPU surface (golden contacts). Reseat the CPU. The CPU should sit vey rasily with almost no pressure applied from your end. Apply thermal greese in the center and place the cooler and ake sure it sits tight. You may have to apply quite good amount of pressure on it.

What cooler does your CPU have. Is it possible to the link containing picture of the cooler or take a snap and attach here ?

Author Closing Comment

ID: 36527226
You reminded me of something, I retraced my steps and tried the system with out RAM. I had done that before but with the old CPU (new at the time, old as in replaced), motherboard etc. This time it stayed on with no vide or anything but the fan was ON for more than 3 seconds~!! Belive it or not I had 2 RAM sticks that were bad. Maybe on top of a bad CPU or motherboard? ohh well, with the third stick alone, it works! with any of the other two sicks, either alone or with the first one, I get the boot loop... Wow, thats crazy!! Thank you very much again!!!! That is why you never go cheap on RAM regardless of what the guy at fry's says.
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Expert Comment

by:Mohammed Rahman
ID: 36529487
I must really appreciate your efforts to sort this out.... you are welcome..!!!

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