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think i have a bad mobo


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#1 greenslam

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Posted 04 March 2015 - 10:09 PM

I have a pc that is refusing to post.

I have removed the ram and left only the power supply attached. It does beep multiple times

As soon as i attempt to install either stick of ram , it refuses to post.

Some background. I recently had swap out the hdd due to failure of my c drive. Event viewer eas showing bad blocks on the hdd1.

I had succesfully swapped the hdd and got it to boot up. 2 days later the pc was running very slow. It only showed 2 gb of ram out of the installed 4 gb. .

I ripped it down and reseated the ram and attempted to reinstall my old video card. The pc failed to post.

I tested each stick by placing it in the seperate ddr3 channels by itself with no success with the post.

Should i buy new ram and test. Or should i just bring it to a shop to have them test the mobo.

I dont have a spare pc to test the cpu/ram in to see if they work.

No multimeter as well.

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#2 zingo156

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Posted 05 March 2015 - 09:21 AM

I will post my general hardware testing procedures, it looks like you have already tried ram swapping. Read through it and give these steps a shot if you feel comfortable doing so:

 

Make sure you have the computer unplugged from power while removing or moving any hardware...

 

Try 1 stick of ram in 1 slot at a time (remove all other ram sticks). Move it to the next slot until you have tried that stick in all slots by itself. If you still have no post, try a different stick of ram in each slot by itself. If you have issues with the stick in 1 particular slot (a no post for example) the slot may be bad. It is also possible you have a bad stick of ram instead of the slot being bad, in this case the ram stick should cause the same problem all slots.

 

You may have a memory controller issue in which case if you have 4 slots, 2 may not work. With intel it should be 2 slots next to each other channel 1 might be slot 0,1 and channel 2 might be 2,3. Trying with 1 stick at a time in all 4 slots is the best way to test everything.

 

If you never get a stable system with just 1 stick of ram in 1 slot (trying all sticks by themselves) try removing all non-essential hardware to get into bios:

 

Disconnect pci cards, pci-e cards - except a video card unless you have onboard in which case use the onboard video and pull the video card, hard drives, dvd drives, disconnect all usb headers as well. You should only have the power supply, main board, 1 stick of ram in 1 slot, the cpu and cpu cooler connected. You can also plug in a monitor and keyboard. Now try to power on the machine. If at this point you have no post screen or video etc, unplug the computer and pull the stick of ram, power back on and listen for a post fault beep code, you will need to hook up a motherboard speaker to hear any post fault code, if this is a laptop it should be built in.

 

If you get no response next: remove all of the components from the computer case and connect only essential hardware (cpu, motherboard, 1 stick of ram, power supply 24pin and 4pin connectors) outside of the case, place the motherboard on a non-conductive surface, a wooden table will do fine. Then try to power on again, you can short the power button pins on the motherboard, don't worry this is exactly what the power button does. Just touch a metal item to both power button pins to try to power the mainboard when outside of the computer case.

 

While you have the computer apart, look for blown or bulging capacitors on the mainboard and video cards etc Examples please report any caps you suspect may be bad, you can take a picture and post here if you are unsure.


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#3 greenslam

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Posted 05 March 2015 - 10:40 AM

 

 

 

Disconnect pci cards, pci-e cards - except a video card unless you have onboard in which case use the onboard video and pull the video card, hard drives, dvd drives, disconnect all usb headers as well. You should only have the power supply, main board, 1 stick of ram in 1 slot, the cpu and cpu cooler connected. You can also plug in a monitor and keyboard. Now try to power on the machine. If at this point you have no post screen or video etc, unplug the computer and pull the stick of ram, power back on and listen for a post fault beep code, you will need to hook up a motherboard speaker to hear any post fault code, if this is a laptop it should be built in.

 

If you get no response next: remove all of the components from the computer case and connect only essential hardware (cpu, motherboard, 1 stick of ram, power supply 24pin and 4pin connectors) outside of the case, place the motherboard on a non-conductive surface, a wooden table will do fine. Then try to power on again, you can short the power button pins on the motherboard, don't worry this is exactly what the power button does. Just touch a metal item to both power button pins to try to power the mainboard when outside of the computer case.

 

While you have the computer apart, look for blown or bulging capacitors on the mainboard and video cards etc Examples please report any caps you suspect may be bad, you can take a picture and post here if you are unsure.

 

 

No obvious bad caps.

 

The only time I get a response from the speaker is when no ram is installed.  Either stick of DDr3 ram in the 2 DDR3 channels does not give a post beep. 

 

Since I get a repeating beeping sound w/ no ram installed,  do you still wish me to remove the Mobo from the case and attempt to get it post outside out of the case?

 

Edit:  getting beeping sound w/ no connectors attached to the mobo other that the power connections from the psu.  all sata connectors have been unplugged and no cards plugged in.


Edited by greenslam, 05 March 2015 - 10:55 AM.


#4 zingo156

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Posted 05 March 2015 - 10:47 AM

I would give it a shot, it can't hurt since either way you will likely need to remove components to replace them. If you have a spare power supply laying around, you might give that a shot before tearing it apart.


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#5 greenslam

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Posted 06 March 2015 - 02:55 PM

Virtually positive its the mobo. Bought fresh ram. The pc posted with a single stick of new and old ram. However it was not posting with attempted retests of the one time succesful post.

#6 zingo156

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Posted 06 March 2015 - 03:34 PM

Virtually positive its the mobo. Bought fresh ram. The pc posted with a single stick of new and old ram. However it was not posting with attempted retests of the one time succesful post.

I am a bit confused, sorry, did it post two times once with old and once with new ram (single stick) but then fail to post when retesting with those same sticks?

 

If you have the same issues with new ram as the old ram, I would put my money on the motherboard or the psu, cpu's rarely fail. In all of my years in retail I had seen a hand full of cpu's fail but hundreds of failed motherboards and psu's, also just because something powers on does not mean the psu is good.

 

You only need 4 components to get a successful post: PSU, 1 stick of ram, motherboard and the cpu. Unfortunately when you get down to those 4 and have a no post, the only option is to replace parts. Since you have replaced ram, the next option would be to try replacing the motherboard or psu.


Edited by zingo156, 06 March 2015 - 03:36 PM.

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#7 YeahBleeping

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Posted 06 March 2015 - 06:41 PM

Could you give us the exact beep codes?  You may be able to resolve this by resetting the cmos but it would be nice to get the beep code so we could look it up.  All you keep saying is its beeping .. the beeps are codes to tell you whats wrong.  Your motherboard's manual should have a list of beep codes.



#8 greenslam

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Posted 06 March 2015 - 08:39 PM

It gave me a steady beeping sound with no ram installed.

The pc was freezing on me intermittently. The psu maybe a culprit as well.

The mobo is aasrock n68c-ucc. I had another old n68 board that i attempted to get posting with the same psu. It failed to post as well.

#9 zingo156

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Posted 09 March 2015 - 07:10 AM

It gave me a steady beeping sound with no ram installed.

The pc was freezing on me intermittently. The psu maybe a culprit as well.

The mobo is aasrock n68c-ucc. I had another old n68 board that i attempted to get posting with the same psu. It failed to post as well.

Did that board post with a different psu? This would be enough to warrant trying with a different psu on the newer computer. If you have a multimeter, you could test the psu:

 

Reading and Testing Desktop PSU Rail Voltages
 
Caution: Please read the following before continuing.
 
 
* Since it will be necessary for your computer to be on during this procedure, you need to be aware that you will be working with live 12Volt DC potentials, which if handled improperly may lead to electrical shock. 
 
* There are electronics inside the case that are very susceptible to electrostatic discharges. To protect your computer, touch the metal of the case to discharge yourself of any electrostatic charges before touching any of the components inside.
 
* If you are not comfortable doing this procedure, then I would suggest that you not use this tutorial. The risks involved are minimal, but are there nevertheless. Anyone who uses this tutorial will be doing so at their own risk.
 
 
There are two devices commonly used to read the rail voltages: a PSU tester, and a multimeter. 
 
The PSU tester is the easiest to use since all that is necessary is to plug the different connectors into the tester and read the results on the LCD display. The problem with most of these is that they only perform a pass/fail test.  They will not provide you with actual voltage readings.
 
There are a variety of multiple meters, but this tutorial will address Analog and Digital multimeters. The advantage of these meters is that you will be able to obtain accurate real time voltage readings.
 
For those of you who wish to know more about multimeters there is an excellent article in Wikipedia.
 
 
Analog Multimeter
 
th_analogedited.jpg
 
 
An Analog multimeter is a little more complicated to use. Both Analog and Digital multimeters need to be set to the appropriate voltage, but with an Analog multimeter, you will need to choose the voltage range and must read the proper scale. 
 
The Analog multimeter uses a needle display which moves from 0 across the scale until it reaches the voltage being tested. This multimeter has five major linear divisions with multiple scales to read a variety of ranges. An example would be three different ranges. The first is graduated in increments of 0 through 5, the second, 0 through 10, and the third, 0 through 25. Each of these ranges are subdivided into divisions that are graduated into tenths. In order to read 12 volts the 0 through 25 range would be the appropriate one. 
 
Because DC voltage has positive and negative potentials this device is polar sensitive, this means that if you reverse the two probes when reading a positive DC voltage it will read as a negative voltage. This is actually necessary to read negative DC voltages. The two probes are differentiated by their color, Black (negative), and Red (positive). To read a positive DC voltage, the correct probes must be used with their corresponding potentials (positive to positive and negative to negative). 
 
With the probes being used normally to read a negative DC voltage, the needle moves from the 0 to the left, "pegging" the needle. By reversing the probes you can properly read the negative voltages.
 
Digital Multimeter
 
th_digitalmeteredited.jpg
 
 
The Digital multimeter (DMM) is much simpler to use. As was mentioned previously, you will need to set the appropriate voltage. One of the advantages is that the DMM has an LCD display with a numeric readout, so there are not any multiple scales to read. Another advantage is that most DMMs are autoranging when reading voltages, which means that you will not need to set the range with these DMMs. A DMM will read both positive and negative DC voltages and display them correctly. When reading a negative voltage, a minus sign will appear on the display before the numeric value. This still is a polar sensitive device, so you will still need to use the positive and negative probes with their corresponding potentials. 
 
There are five different DC rail voltages which are color coded. The Black wires are always negative.
 
Yellow +12VDC
 
Blue -12VDC
 
Red +5VDC
 
White -5VDC
 
Orange +3.3VDC
 
There are only three voltages that can be measured easily without disconnecting the 20/24 pin connector from the motherboard: +12V, +5V, and +3.3V.
 
The +12V and +5V voltages can be read from a four pin Molex power connector.
 
Four pin Molex power connector
 
th_250px-Molex_female_connector.jpg
 
 
The same voltages can be taken from a four pin SATA power connector, but in order to read the +3.3V you will need to read this from a five pin SATA power connector as seen below.
 
Five pin SATA power connector.
 
th_sata-power-cable.jpg
 
To read these voltages you will need to insert the Black (-) probe into any of the black  sockets, and insert the Red (+) probe in the different colored voltage sockets.   To read the voltages from a SATA power connector it is easiest to insert the probes into the bac k of the connector where the wires enter.  Unfortunately the sockets of the modular SATA power connectors are not accessible from the back, so the readings will need to be made from the socket side.  Some probes are going to be too large to fit in these sockets, so you may need to insert a piece of wire into the socket of which you want to read the voltage of and place the probe on this for your reading.  To reduce the potential of creating a short I would suggest taking the ground potential from another connector so that the two wires will remain physically separated.
 
Caution:  It is very important to make sure that you don't allow the two probes to touch each other when taking the voltage readings.  This will cause a short which could damage the PSU or other components.
 
To get accurate readings of the rail voltages it is important that there be a load on the PSU. In order to do this I would suggest downloading Prime95 and run the Just Stress Test for this purpose. This program was designed to be used by overclockers to put a full load on the RAM and CPU to determine the stability of their overclocking.  Because of this it will put stress on the CPU and RAM which will create higher than normal temperatures.  For this reason I would suggest not running this program any longer than is necessary.  I would also suggest that an inspection be made of the interior of the case to make sure that there isn’t an accumulation of dust which would impede adequate cooling.  Pay special attention to the heat sink and fan assembly on the CPU.  If there is a dedicated graphics card with a fan installed on it, look at this fan as well.      
 
 
Readings should not have variances larger than +/- five percent.  
 
Maximum.........Minimum
12.6V.................11.4V
5.25V.................4.75V
3.47V.................3.14V

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#10 greenslam

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Posted 09 March 2015 - 01:49 PM

You can close this topic.  

 

I decided to go out and purchase a refurbished system. 

 

I thank you for the assistance lent so far. 



#11 zingo156

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Posted 09 March 2015 - 01:58 PM

We don't generally close threads. Happy computing!


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