Computer Turns ON—No Beeps—Black Screen

[earguy]

Something new this morning. It "feels" like electricity is running through the case. I touched it with my arm while reaching across it for something and there was a slight "bite" to it. This happens with the PSU switch in the off position and unplugged. When I press the power button for a few seconds, it goes away, but comes right back once the unit is turned back on. Does this sound like a short somewhere?

 

[Larry Sabo]

Are you saying that with the computer disconnected from the mains, you can feel a tingle when touching the case? If so, does your bench have a conductive surface, like stainless steel sheeting? Are all other cables disconnected when this happens, e.g., Ethernet, speakers, etc.?

 

[gadgetfixup]

Something new this morning. It "feels" like electricity is running through the case. I touched it with my arm while reaching across it for something and there was a slight "bite" to it. This happens with the PSU switch in the off position and unplugged. When I press the power button for a few seconds, it goes away, but comes right back once the unit is turned back on. Does this sound like a short somewhere?

That's actually quite common with non-UL power supplies. You won't feel the electricity typically with your hand but of you touch the case with forearm you'll notice the case is energized and make your arm tingle. I doubt it has anything to do with the issue you're experiencing but does indicate your power source or cable doesn't have a good earth ground (3rd wire or prong) as that PSU leakage should be dumping to the ground so it doesn't bite you.

 

[earguy]

Are you saying that with the computer disconnected from the mains, you can feel a tingle when touching the case? If so, does your bench have a conductive surface, like stainless steel sheeting? Are all other cables disconnected when this happens, e.g., Ethernet, speakers, etc.?

I have the unit on top of an anti-static mat that is on a particleboard table. All devices disconnected and you can still feel a slight vibrations as you lightly run the tips of your fingers across a metal portion of the case. When I shut down the power, unplug the cord, it still is there. However, when I shut it down, unplug the power cord and then turn the PSU switch to the off position, it seems to go away.

Are you saying that with the computer disconnected from the mains, you can feel a tingle when touching the case? If so, does your bench have a conductive surface, like stainless steel sheeting? Are all other cables disconnected when this happens, e.g., Ethernet, speakers, etc.?

 

[earguy]

That's actually quite common with non-UL power supplies. You won't feel the electricity typically with your hand but of you touch the case with forearm you'll notice the case is energized and make your arm tingle. I doubt it has anything to do with the issue you're experiencing but does indicate your power source or cable doesn't have a good earth ground (3rd wire or prong) as that PSU leakage should be dumping to the ground so it doesn't bite you.

That's what it feels like. Thanks. I was becoming concerned.

 

[earguy]

I have to leave and won't be back for awhile. However, please feel free to add to this post any idea that you may have concerning this issue. I really do appreciate all the help. Thanks

 

[B Trevathan]

OK. How about UBCD?

Sure that will work fine, but with a Linux CD you will get a better GUI to help test the hardware. Running any live CD will help you eliminate the problem of not knowing if the problem is hardware or software related.

 

[brandonkick]

Did you take the advice given here, and break the machine down to it's simplest components?

Take everything out of the case if you have to, and set up just the motherboard on an anti static mat with nothing
connected but a power supply and a processor. Try manually starting it by jumping the green and black wires
on the power supply. It should start, and you should hear beeps because there is no system memory. If at this point
you aren't even getting beeps, then you have major problems with either your CPU, Motherboard or Power Supply.

If you do get memory beeps, then start by adding back in the system memory.

Now you should no longer get "memory beeps".

And at this point, the system should be booting into the BIOS.

Now add back in the rest of the components you've removed, one at a time and then boot the machine each time
you've added a new piece until you either have them all added back in, or the machine fails to boot. If the machine
fails to boot during this process, you will find the last component entered is almost always the culprit.

 

[brandonkick]

Also, realize that hunting down things like this can start to consume large amounts of time.

The client may want to just go with getting a new machine. As he may be investing a ton
in the way of paying your hourly to do this kind of work. And if your not billing him hourly
then your probably eating money on this one.

Just something to think about.

 

[earguy]

Did you take the advice given here, and break the machine down to it's simplest components?

Take everything out of the case if you have to, and set up just the motherboard on an anti static mat with nothing
connected but a power supply and a processor. Try manually starting it by jumping the green and black wires
on the power supply. It should start, and you should hear beeps because there is no system memory. If at this point
you aren't even getting beeps, then you have major problems with either your CPU, Motherboard or Power Supply.

If you do get memory beeps, then start by adding back in the system memory.

Now you should no longer get "memory beeps".

And at this point, the system should be booting into the BIOS.

Now add back in the rest of the components you've removed, one at a time and then boot the machine each time
you've added a new piece until you either have them all added back in, or the machine fails to boot. If the machine
fails to boot during this process, you will find the last component entered is almost always the culprit.

I plan on doing just this tomorrow. Thanks again. I'll post back the results.

 

[earguy]

Also, realize that hunting down things like this can start to consume large amounts of time.

The client may want to just go with getting a new machine. As he may be investing a ton
in the way of paying your hourly to do this kind of work. And if your not billing him hourly
then your probably eating money on this one.

Just something to think about.

Yes, definitely something to think about.

 

[NETWizz]

I would like to add a little bit here...

Please take the RAM out and put it (one module at a time) into a working system and run something like MemTest86+ (or similar) on each stick individually... Then run it with ALL of the sticks present, so you test dual-channel etc.

DO NOT run the BIOS update unless the system is stable. If it messes up you WILL need a motherboard for sure (if you don't already).

Take the motherboard OUT of the chassis... Sometimes some hack system builders put too many metal standoffs under the motherboard causing it to short to the chassis; hence, you MUST take it out to inspect that. A recommendation might be to take a LARGE piece of paper and use a marker to mark out each hole then verify that is EXACTLY where the stand-offs are located.

Some motherboards are finicky... If you try a bare bones POST (power -on self-test) read the manual to see which slot the RAM should be in... some work ONLY with the RAM in either slot 1 or slot 0.... Either way READ. Most do NOT care.

The minimum config for the system to POST is a power supply, CPU /w Cooler installed, one (1) stick of RAM, an monitor/keyboard (no mouse)... If no monitor port is integrated on the motherboard, you will need to add a video card too.

Double-Check the 4-Pin connector (or 6-pin connector is installed, too).

Reset the CMOS jumper if there is one. If not read up to see if there is an alternate procedure like holding down some keys or something to flush ALL the system configuration parameters. You SHOULD be able to set the time.

Someone mentioned inspecting the CPU... it is not a bad idea, but pins do not bend themselves after the fact. It IS possible to have a damaged CPU that is missing a ground pin and it still works. It is highly unlikely, but clean the cooler, inspect it, and install it with fresh thermal interface material.

It is EASY to test the Power Supply under load... Basically, you turn on the computer and whether it POSTS or not WITH IT RUNNING you get a volt meter (make certain you are in VOLTS NOT AMPS OR YOU WILL SHORT IT) and you measure the voltage difference between the ground (BLACK) an the Red, Orange, Yellow... You should get 5, 3.3, and 12 respectively... The orange is very tough to check... you might need to back-probe the ATX power feed. If you have multiple rails they must EACH be checked.

It would NOT be a bad idea to inspect the capacitors in the power supply (with it off and disconnected) too... DO NOT TOUCH THEM... they may shock you.

Check your Power:

Make certain you have a proper three(3) prong power cable for the power supply and that your power source is checked with one of these (or similar). http://www.amazon.com/TRC-90265-6-0...d_cp_hi_4?ie=UTF8&refRID=0XNM6NMN7A4SFPRCQWMP

I personally recommend GFCI just in case there is a ground fault issue. I carry one of these:
http://www.amazon.com/TRC-90265-6-0...d_cp_hi_4?ie=UTF8&refRID=0XNM6NMN7A4SFPRCQWMP

Again, you should TEST it with the above tester (or similar) to confirm the GFCI works too...



*************************************************************

Typically if a system will not POST and it is not the RAM or hanging on a drive (unlikely with a blank screen) it is either the Motherboard or Power Supply.

You may want to test the Power Supply with a different computer to double-check it is okay. If it is the motehrboard, you will likely need a new motherboard, RAM, and CPU; since, older DDR2 RAM and an AMD AM2 (or 939) is not going to be compatible with any new motherboards.




I should say when testing the original motherboard with known good RAM y ou will want to try the stick in each of the two slots (or 4 slots) to test each slot as well.

 

[earguy]

I would like to add a little bit here...

Please take the RAM out and put it (one module at a time) into a working system and run something like MemTest86+ (or similar) on each stick individually... Then run it with ALL of the sticks present, so you test dual-channel etc.

DO NOT run the BIOS update unless the system is stable. If it messes up you WILL need a motherboard for sure (if you don't already).

Take the motherboard OUT of the chassis... Sometimes some hack system builders put too many metal standoffs under the motherboard causing it to short to the chassis; hence, you MUST take it out to inspect that. A recommendation might be to take a LARGE piece of paper and use a marker to mark out each hole then verify that is EXACTLY where the stand-offs are located.

Some motherboards are finicky... If you try a bare bones POST (power -on self-test) read the manual to see which slot the RAM should be in... some work ONLY with the RAM in either slot 1 or slot 0.... Either way READ. Most do NOT care.

The minimum config for the system to POST is a power supply, CPU /w Cooler installed, one (1) stick of RAM, an monitor/keyboard (no mouse)... If no monitor port is integrated on the motherboard, you will need to add a video card too.

Double-Check the 4-Pin connector (or 6-pin connector is installed, too).

Reset the CMOS jumper if there is one. If not read up to see if there is an alternate procedure like holding down some keys or something to flush ALL the system configuration parameters. You SHOULD be able to set the time.

Someone mentioned inspecting the CPU... it is not a bad idea, but pins do not bend themselves after the fact. It IS possible to have a damaged CPU that is missing a ground pin and it still works. It is highly unlikely, but clean the cooler, inspect it, and install it with fresh thermal interface material.

It is EASY to test the Power Supply under load... Basically, you turn on the computer and whether it POSTS or not WITH IT RUNNING you get a volt meter (make certain you are in VOLTS NOT AMPS OR YOU WILL SHORT IT) and you measure the voltage difference between the ground (BLACK) an the Red, Orange, Yellow... You should get 5, 3.3, and 12 respectively... The orange is very tough to check... you might need to back-probe the ATX power feed. If you have multiple rails they must EACH be checked.

It would NOT be a bad idea to inspect the capacitors in the power supply (with it off and disconnected) too... DO NOT TOUCH THEM... they may shock you.

Check your Power:

Make certain you have a proper three(3) prong power cable for the power supply and that your power source is checked with one of these (or similar). http://www.amazon.com/TRC-90265-6-0...d_cp_hi_4?ie=UTF8&refRID=0XNM6NMN7A4SFPRCQWMP

I personally recommend GFCI just in case there is a ground fault issue. I carry one of these:
http://www.amazon.com/TRC-90265-6-0...d_cp_hi_4?ie=UTF8&refRID=0XNM6NMN7A4SFPRCQWMP

Again, you should TEST it with the above tester (or similar) to confirm the GFCI works too...



*************************************************************

Typically if a system will not POST and it is not the RAM or hanging on a drive (unlikely with a blank screen) it is either the Motherboard or Power Supply.

You may want to test the Power Supply with a different computer to double-check it is okay. If it is the motehrboard, you will likely need a new motherboard, RAM, and CPU; since, older DDR2 RAM and an AMD AM2 (or 939) is not going to be compatible with any new motherboards.




I should say when testing the original motherboard with known good RAM y ou will want to try the stick in each of the two slots (or 4 slots) to test each slot as well.

Thank you for taking the time to write all this. I will be using a known good PSU in the machine to rule out the current PSU as the (likely) problem. Only have one other desk top handy so hopefully it will take the RAM modules so as to run a Memtest86+. I had another computer a month ao doing similar things and it ended up being the motherboard. I may, after doing the above tests, just suggest copying his data files and then getting a new computer.

 

[earguy]

Thanks to everyone for your help. I have determined that it is most likely a motherboard issue and have advised my client to let me perform a data transfer to an external hard drive and to get a new computer. He has agreed. Again, thanks.

 

[PcTestCard.com]

I would suggest reseat the CPU and clean the RAM module pins with a paper rubber for better contact.
Also, try power on the PC without the RAM and hear if there is any beep.

Seems to me the mobo could be faulty.

Hope this helps.
Bill
Tech Manager