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Computer not booting up

  • Homebuilt
  • Systems
Last response: in Systems
November 16, 2011 6:38:07 PM


Built my first system 2 months ago and it worked great since.

Since 2 weeks ago I had been getting CMOS checksum error on odd occasions on starting. I haven't done anything to the bios and the motherboard was new so I didn't think it was the battery.

Last night the computer just chit itself after leaving it on idle during dinner. Tried to restart it many times but it just doesn't get to the HDD to boot up Windows 7. The monitor is showing Check signal cable.

System Specs:
Windows 7 68bits Home Premium
i5 2500K
Gigabyte Z68A-D3-B3
G.Skill Sniper DDR1600 4G x 2
Powercolor HD6850
1T Caviar Black
Thermaltake Spacecraft case with PSU

I have checked all power cables to be connected properly. So I am hoping for luck by replacing the CR 2032 battery today after work. There isn't much else I could do since it doesn't even boot up to the CMOS settings.

Any other recommendations would be appreciated.

More about : computer booting

November 16, 2011 8:03:42 PM

Your motherboard fried or Video card. First try another video card . If nothing the motherboard issue. This happens on cheaper motherboards sometime lower quality power sections. Hope its still under warrenty. A Cmos battery issue will not keep your screen from posting it will just complain about the date not being set and such.

November 16, 2011 9:37:25 PM

thently said:
Your motherboard fried or Video card. First try another video card . If nothing the motherboard issue. This happens on cheaper motherboards sometime lower quality power sections. Hope its still under warrenty. A Cmos battery issue will not keep your screen from posting it will just complain about the date not being set and such.



I will try changing the battery first as I have read other people with similar issues from a failed battery. If that fails to repair the issue I will try the integrated graphics.

Everything is only 2 months old and I have the receipts so it should be under warranty. Lastly, if it is a motherboard failure. How do I go about proving it? Do I take it back to the shop to have them checked? Or just shaft it in their face and tell them it failed?
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a c 122 B Homebuilt system
November 16, 2011 9:42:07 PM

It may not be the motherboard. Looking over you list of components, my first guess would be your PSU.

Before you do anything, work through my standard troubleshooting list:
The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

Breadboard - that will help isolate any kind of case problem you might have.

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

Silence, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
November 17, 2011 12:20:10 AM

Thanks jsc for the detailed reply. Unfortunately I had to put it to waste. I was fortunate enough to revive the computer before I read the reply. Otherwise I wouldn't be able to get online at home now.

This is what I did to solve the problem and I don't know how and why it worked.
1. Changed the motherboard battery but it still didn't boot up.
2. Disconnected the GPU before starting the computer. I didn't have the correct cable to connect to the integrated graphics but I could see the HDD light blinking this time and eventually hear Windows started up.
3. Powered down the computer and reinstalled the GPU before restarting.
4. I also changed the cable connection between PC and Monitor. From DVI - HMDI to now DVI - VGA. Both connections now works.