Do I have a dead motherboard? No beep, no BIOS screen.

[jaquith]

^Ahh Humm - this was originally posted 08-16-2008; I hope the OP resolved it by now?!

 

[pvkeller]

I had similar symptoms - working computer failed, no bios just fans and lights. I suspected the mother board as the problem arose right after I tried installing some memory additional memory.

coming to thread, I took Westcom's advice and bought a multimeter. First time I tried it I got:
Purple 5.09
Green 5.05 (Pre-start) 0.038 (Post-start)
Gray 0.00 (Pre-start) 5.11 (Post-start)
One of Orange, Red, and Yellow 0.00 (Pre-start) 3.11 (Post-start)

So I bought an installed a new mother board - same failure.

I retested with the multi-meter and saw:
Gray 0.00 (Pre-start) 5.11 (Post-start)
Being in a hurry to get this fixed I didn't both asking here and went ahead with a new power supply - same failure

At this point I realized I was missing a system audio device, bought one (cheap, but another trip to the store) - no sounds, no info

The only thing left was the CPU. I bought one of those. Presto, I have my computer back.

So much for being systematic as opposed to randomly swapping parts.

 

[jp@er electronics]

I have been working on a similar type of problem... No bios, No POST beeps... The machine i am working on is a HP Pavilion a6000 in which the fans work but no visual display...

I had to reset rams, NIC card, Modem cards and the CPU itself but to no avail

I was about to give up when i had a look at where the cpu sits and there it was.....

There was a pin bent that does not have contact with the chip.....

What i did was risky.. i used my smallest tip srewdriver to straighten the pin with caution

Once upright i rebooted and there it was working....

I suggest checking the pins, the pins very easily bend so take care and dont over do it..

The pins can overtime bend due to heat.

 

[JayJay0266]

For anybody still looking for why the motherboard doesn't give any beeps, let me share with you this little tidbit I found in my motherboard documentation:

After you plug in the main power connector, there is another one you may have missed.

The second connector will either be an 8-pin or a 4-pin. This is the auxiliary power connector found next to the CPU and you do not need an 8-pin plug there unless you are using a high end CPU, or if the system will be overclocked.

Failure to plug any 4- or 8-pin connector will result in the system not giving out any sort of display or POST signals.

Once I plugged in the 4-pin connector, I got my beeps. Check your motherboard manual for the pin-out to see if this is what you might be missing.

Hope this helps

I am just a one time visitor here and I'm very thankful that this forum allows replies/posts by anonymous readers because I'd like VERY much to respond to what I've been reading. I find this forum to be full of technical savy folks who are looking for help and responders (Weston, for example) who are pretty much experts.

BUT, sometimes the experts may need to consider to start their search for the culprit component by looking at the forest instead of totally focusing on that particular PSU tree. A little sentence like Phantomwriter wrote, before the ten paragraphs devoted to the PSU tree, would have hit the nail right on the head in this particular case. At least it did for me and may have for at least another poster (more below on this).

Yes, it may be a rarity for that auxiliary power connector to NOT be plugged in but for the sake of the quick and simple possible solution of just checking that oversight and ESP. how simple it is to do so - "Man, was I ever glad that I saw Phantom's post before I started to do anything!".

For whatever reason (?) that connector was not plugged in the MOBO on my Dell Dimenion mini tower and it took me a split second to fix the exact same problem that so many posters described in this thread. And no, I did not put this computer together either (it was given to me by friend who upgraded and when I told him I got it going - he said "keep it, you earned it by figuring out what was wrong and I love my new computer anyways"). I see that at least one poster did build his own computer and this solution may very well work for him if he missed plugging in that second power plug to the MOBO.

No meters, no numbers, no reports.. no nuthin. Problem solved.

KUDOS TO the "Phantomwriter". Your post sure DID HELP

 

[TechD71]

😀 I had the same problem. I got no post, no beeps, no floppy during post and no video. I did everything to find the problem. When I got tired and just about given up, I looked at the battery. I replaced it (TURNED POWER OFF FIRST!) and wah lah! IT WAS FIXED!
It was just a bad CMOS Battery. Can you believe that!? A $2 job.

 

[M477M373]

You did shotgunning. You wildly disconnected or replaced parts. You tried to fix it rather than first learn what is wrong first get numbers and facts. You may have even made the problem exponentially more complex by doing things such as the cmos fixing or video card swapping.

You must disconnect or replace nothing. Then take voltage measurements. Your symptoms are classic of a defective power supply 'system' - and a few other things. Shotgunning says we replace all ten other things. Diagnostic procedure says we see what is wrong – then only replace one suspect. You made a useful reply difficult. Why? Your replies will only be as useful as the facts you provide. You provided no numbers. Just speculation from “I moved this and that happened”. You tried to do with eyes what cannot be seen. You speculated even about the power supply being good. A completely defective supply can even boot a computer. And can do what you have seen. Why do you know the supply is good? Speculation. You did not first get numbers.

Put everything back exactly as you started. Take the requested measurements of six critical wire before, and when the power switch is pressed. And then (which you cannot yet do) with the system under maximum load.

Solutions only happen when you break a problem down into parts - then analyze each part - one at a time. Until you have numbers that say the power 'system' is good, then you have no idea - no matter what beeps come from a speaker. Until the power ‘system’ is proven, everything else that is good can act strange or defective. The only answer is one that is definitive. No definitive answers are possible until you have moved the power supply system from ‘still undefined’ to ‘definitively good’ (or ‘definitively bad’). Notice the real world is not binary. Notice more than two possible conditions.

Numbers from those six wires are so chock full of information that the last five posts would be too short to explain it. Want to know where to look next? Post those numbers as explained previously.

Your symptoms imply the power supply is good AND that the power supply is defective, and that other parts of the supply system are good, and that other parts are bad. All possible without specific facts – especially numbers.

BTW, get rid of the battery tester. Had you tested the battery with a meter, then numbers could have said so much more. 'Red area' tells us nothing usefu. Battery could have been perfecty fine for now - and for the next six months. But we will never know. Your tester was subjective - did not provide numbers that could have said whether the battery contributed to the problem.

Westom:
Hello, I have this values powered off : violet 5v gray 0v green 5v red 0v yelllow 0v orange 0v blue 0v white 0v
and powered on: violet 5v , grey 5,3v green 0,1v red 5,3v yellow 11,9v orange 3,1v blue -11,7v white -5v.
Does this mean the PSU is defective? values are under what I expected.. btw tested without memories, and breadboarding, I get no beeps , tried with two different speakers to make sure. Can the silverpaste dry cause this? should I replace it and also under the other heatsink? Thanks!
Matt

 

[smalltalker]

If I understand what was posted. References to -r or lg. are confusing. Therefore means I somewhat doubt some of what I have read.

A) When power is off:
Green wire: Is that +4.53 volts (not -4.53)? 4.53 volts would be normal.
Gray wire: - not listed AND a critically important signal.
Purple wire: a stable 4.99 or 5.00 volts. But I don't understand what all those other following numbers mean.

Blue wire: is that -11.97 or + 11.97 volts. Either way, that is defective.
Orange wire: -3.35 or 3.35 volts. Again, defective.
-r: Is that red? 5.17 volts. Again defective.
-y: Is that yellow? 12.24 volts. Again defective.

Each is defective because there must be no voltage as ordered by the green wire.

B) Moving on to "with it powering up-". First should be listed are the green, gray, and purple wires.
Green: Is that 0.21? I don't know what 0.03 is. However those numbers would be OK.
Purple wire not listed.
Gray wire not listed.

lg.orange: Do you mean orange? Is that 3.28 within a second? 3.28 volts is marginal when considering other voltages. But within spec and sufficient to permit booting.
rd/pk: Is that red? 5.03 or 5.16 volts is good.
yel: Yellow wire at 11.83 or 12.25 is good.
blue: Not asked for and not relevant.

By guessing (only a preliminary conclusion) - those voltages are stable. However the critical gray wire voltages are not provided. Power off voltages on red, orange, and yellow make no sense; imply a problem and a reason for weird computer operation. Are those numbers correct or did I simply read what was posted wrong?

The gray, orange, yellow, and red wire voltages should change in response to the power switch and be stable within a second. With meter delays, stability could take less than two seconds. But the red, orange, and yellow wires must be stable faster than the gray wire. I am guessing that is what you saw and need confirmation.

What you are looking at: Purple wire is power to the controller electronics so that it can monitor the power switch and remember how the switch was last pressed. Green wire is the power supply controller ordering the power supply to power on. Those 0. 2 and less voltage numbers mean the supply should power on AND that a sufficient safety margin exists - that other hardware parts in that circuit are working properly. Just a sampling of so much more information embedded in those numbers.

You report voltages on the red, orange, and yellow wires when none should exist. Are you reporting correctly or is hardware defective?

Voltages on other connectors are irrelevant. Fan defaults to full on. Then fan controller hardware takes over to throttle back that fan. Fan reports little other than its and its controller is working. Not relevant to your problem.

Posting those ATX specs and *.pdfs provides nothing useful. Other facts necessary to 'massage' those numbers are not found there. For example, what number does the spec give for yellow wire? 11.4 volts? A reading of 11.7 or less means a defective power supply (especially later when the system is truly drawing a load and the supply can be fully confirmed). Also relevant are relations between those numbers. But for now, we are only concerned about those numbers during boot.

These numbers only discuss whether the system should boot. Other numbers taken with the system fully loaded will determine if the system is fully OK. Irrelevant for now. Before definitively answers that boot question, first, 1) what are the numbers on the red, orange, purple, and yellow wires when the system is powered off? And 2) what are the gray wire numbers? Only then do we move on to the next step.

BTW, you motherboard should have some type of speaker or sound (beeping) device? Does it? Another important diagnostic tool only if your board has some beeping device. Does the board beep or can you identify a small round 'beeping' device?

Finally, this is an HP? Which model number so that HP information specific to your machine can be obtained from the HP web site?

OK. With missing information provided and corrections to what was posted, we may have achieved one step towards a solution. Sentences 1) and 2) first must be answered.

--- - -

I have a DELL XPS/Dimension XPS Gen 4.
Nvidia 6800 video card.
Pentium 4 Prescott Dt, Pentium 4 Prescott DT, 3.4GHZ, 1 MEGB, 800FSB

It is exhibiting similar behavior as in most other cases listed here (no beep, no video, all fans, drives power up).
Checked CMOS battery. It was around 2.8. Replaced with 3.3 v new battery. No improvement.
Checked monitor - works with another computer. Works with another computer using same video cable.
Other monitor does not work with this DELL XPS either (no signal).

Here are the voltages measured with a multimeter.
PSU plugged in - Not Powered on.


Green Wire 3.37 stable
Grey Wire 0.00
Purple Wire 5.13 stable

Blue Wire 11.87
Orange 0.00-0.01
Red 0.00
White 0.00

Powered up

Green Wire 0.13 stable
Grey Wire 5.12 stable
Purple Wire 5.11 stable

Blue Wire 11.92 (or -11.92)
Orange 3.36
Red 5.12
White 11.86

P5 Connector (for graphics card) 11.82

I did get some beeps when I pulled some memory out of banks (so that there were not matching pair of memory in a bank).

Computer was working fine until about couple of weeks ago. (Used to have some trouble with lockups). running Win XP pro. I have tried other monitors but no luck. Dell no longer makes the power supply for this model and the only thing I can find on ebay are refurbs. So if it is not the power supply, I'd rather not try to get another one.

I tried getting all the readings you had asked for from other users.

Any help you can provide is greatly appreciated.

 

[808dude]

Me, too with the non-beeping problem - new after a four-week shutdown while I was away. If Westom is still divining PS problems, here are my data for this no-beeper motherboard. (Are other voltages needed at this point?)

(1) PS off
purple: 4.98
green: 4.01
gray: 0.03

(2) PS on - note that fans run for five seconds, then off five, ad nauseum, hence the following conditional readings:
reporting voltages below as: (fans not running)/(fans running)
purple: 4.98/4.97
green: 4.01/0.03
gray: 0.01/4.63

Other notes:
Mobo is an ASUS IPIBL-LB from HP m8307c. I did a bit of shotgunning (no replacement stuff, just out-of-sequence checks) before finding this thread, thus perhaps not testing under Westom's ideal conditions. So before I checked the CMOS battery, re-seated RAM, and pulled off chip-fan and heatsink to look for board ID, the fan on/off symptom didn't exist - that is, the fans ran continuously, but always with no beep or screen activity. Not to further complicate things by reassembling partially, I left all drives disconnected and auxiliary boards "removed" during voltage measurements.

 

[pwrhamr]

Did you people notice that no one is working this thread? If you have a problem start a new thread for your issue. Wake up.

 

[808dude]

Did you people notice that no one is working this thread? If you have a problem start a new thread for your issue. Wake up.

Yet magically, YOU noticed it and replied, in your capacity as arbiter of propriety for the forum...

OK, there's no need for sarcasm or, as in your case, downright dickishness. Many helpful participants to forums such as this will monitor threads they have participated in for months or years, which, when a problem recurs for many users, is a practice that only makes sense. Why start over and answer the question from scratch when it's possible to deal with it in general or specific terms in one longer thread? Moderators generally close threads when they believe they've reached the stage of not being useful, and that hasn't happened here, yet.

 

[pwrhamr]

Whatever dude. No sarcasm intended..... The problem with your argument is you try to be more "dickish" than you perceive me to be. Congratulations you accompished it.

- New threads are needed to keep things organised, succinct, and able to give the person asking the question the best chance of solving their issue, not yours. Having 15 people trying to fix their individual problems on one thread confuses and complicates the "help" someone is looking for.
- Not everyones problem is the same, even if it has similar symptoms.
- Having numerous issues on a single thread makes it almost impossible for others to use search to find similar threads that have information to help them.
- Did you ever wonder if the person who started this thread ever got their problem fixed before it was hijacked by other folks?


Start a new thread.

 

[smalltalker]

Solved - Apparently its a dead graphics card.

 

[trio3d]

I'm also having a problem like Op and Sathar. Home build working for 3 years with Asus A8N-SLI Deluxe with two Corsair 1GB sticks. I would get to BIOS post and then it would sit at a black screen for about 20 to 30 minutes, then finally show Windows loading screen, then usually work fine (occasionally freezing).
I ran diagnostics on RAM and HDD....all came back okay. I then tried experimenting.
I tried each 1 GB stick separately and they both worked perfectly. However, the problem would happen again if I put both sticks in together.
I was using SATA hdd's. I installed WinXP 2 times and still had the same problem. I installed WinXP on an IDE hdd, with SATA as secondary drive and everything works fine, even using both sticks of RAM.

I experienced a similar issue on my laptop. I found out it was the optical drive, so i removed it off the bay.. and nw its perfect.
I assume some peripheral could be malfunctioning. Try removing all, except your bootdrive.

 

[pappupager]

I bought a new MSI motherboard G41M-P23 previously I was using an Intel d102ggc2(max. 2 gb ram is the reason I changed my motherboard). I have a Intel Pentium D 2.8 Ghz processor with an ATI HD 4850 graphic card ( this was working fine on my previous Intel board) and a mushkin ddr3 1066 4gb ram which I bought with my motherboard yesterday. I installed it myself yesterday but now when i switch on most of the times i have no display. But when it is Working i get no errors.

I am not so sure about my processor but I think it is a 820 Smithfield 2mb cache and 800 mhz I bought it sometime in 2006.

 

[Vedauwoo]

As I would have expected, the psu readings were all w/in specs.
I asked for numbers from a specific procedure that required specific actions. Provide the numbers - not subjective answers. You don't appreciate what those numbers are saying. Again my reply says nothing useful. It will only be as useful as the facts you provide. You provide no facts - just a subjective declaration.

For example, what is the number when the system is off. What does the number do as the power switch is pressed. What specs did you use for those response times. And did you fully load the system? With what tasks multitasking to each peripheral? Of course, everything is fully connected - ignoring what some other web sites recommend.

Your help is only as good as the facts you provide. It said to give me numbers and responses to each color wire. No numbers means the best one can do is provide junk science assistance.

Same / similar issues....PC running great, then randomly shut off a couple of time then would no longer even make it to BIOS..

Original Power Supply taken to computer shop for testing...toild it had an erratic 5v reading, and picked up a new one...did not fix the issue

Here are the "numbers"

PC off (Switch off on back of PSU - unit plugged into 120vAC)
Purple: 0.00 Vdc
Green: 0.00 Vdc
Grey: 0.00 Vdc
Orange: 0.00
Yellow: 0.01
Red: 0.00
(Orange Yellow and Red on the 20+4 connector)

PC off (Switch ON on back of PSU - unit plugged into 120vAC)
Purple: 5.13 Vdc
Green: 5.12 Vdc
Grey: 0.00 Vdc
Orange: 0.00
Yellow: 0.01
Red: 0.00
(Orange Yellow and Red on the 20+4 connector)

PC ON [Front button] (Switch ON on back of PSU - unit plugged into 120vAC)
Purple: Drops from 5.13 to 5.11 Vdc and remains constant
Green: Drops from 5.12 to 0.06 Vdc and remains constant
Grey: Starts at 0.02 Vdc and climbs to 5.06 Vdc and remains constant
Orange: climbs from 0.14 to 3.34 and remains constant
Yellow: Climbs from 0.01 to 12.00 Vdc and remains constant
Red: Climbs from 0.00 to 5.11 Vdc and remains constant
(Orange Yellow and Red on the 20+4 connector)

Other symptoms:
Power light at MB - On when PSU switched on
NO audible beeps except when turning back off, faint semi-chirp
Fans running (including fan on Video Card)
No sound from HDD / No HDD light (except a flicker when button is pressed)

- Previously, HDD light came on and remained on when start button pressed.

 

[skyodyssey32]

tag for later

 

[louis309]

Adding pin numbers means you consulting someone else and therefore have made concluions from information not requested. That causes confusion. Adding to what I asked for only confused issues. Forget everything you provided to learn from what is provided below. Forget everything except what you saw on any one red, orange, yellow, green, gray and purple wire. And what you answered concerning the speaker. Now appreciate the massive - so much - information that came only from those requested voltages.

The power supply controller is ordering the CPU to execute. So finally we have accomplished only one thing. We know the power supply system is 100% (definitively) good. Only now can we move on to other suspects - and never look back.

What you saw from those numbers: when the power switch was pressed, green wire ordered the power supply to power on. The power supply sees all critical voltages obtain minimum values. Then we confirmed those value are sufficiently above what is required. Power supply tells the controller (via gray wire) to let the CPU start working. Entire power supply system is 100% good.

According to those numbers, your system is not consumed any significant power.

Next, CPU only looks at a very few system functions. It reads a first instruction from the BIOS to start setting up other functions. IOW you could remove all disk drives, sound cards, network cards, keyboard, mouse, etc and the CPU does not care.

The CPU starts by viewing only a few items, putting letters on the video (using the most primitive video functions), and announcing problems with speaker beeps. One of the first things checked is memory. If memory is not seen, then CPU beeps the speaker. Simply remove only memory boards. If CPU executes and if speaker is working, the CPU beeps that speaker using almost zero hardware. But CPU does not execute; it does not even beep the speaker.

( BTW: speaker – not the soundcard speaker. Soundcard is just as irrelevant as the mouse and disk drives. A tiny speaker on the motherboard that only beeps.)

No letters on the video. No speaker beeps. Now the numbers of suspects has been reduced from so many hundreds to maybe only 20. (Not even on the list of many hundreds suspects is disk drive, keyboard, etc - discussed later). Very few functions are necessary for a CPU to execute and beep the speaker. So now we have limited failure to maybe twenty suspects; and all are on the motherboard.

I assume you have connected the power connector near the CPU. Failure is probably in a tiny area of motherboard near CPU and adjacent large support chips - also called the Northbridge and Southbridge.

A failure that is visible almost never exists. But it is all you have left to inspect without far more advanced equipment. Inspect for stray metal fragments or anything that might short the motherboard in a region around the CPU and those large support chips. Carefully remove the motherboard looking for something (such as a metal standoff) that might have broken through a green coated solder trace. Maybe inspect for a cracked trace or some other mechanical defect in that area.

All but the rarest defect are not visible. We have reduced the defect area only to components in a small area of the motherboard. If the defect is not visual, you have no alternative but to replace the motherboard.

If I was to bet on a suspect (if I was a Roulette player), I would bet on a total failure of the CPU power supply - a function powered by the four (or six) pin connector near the CPU. That failure means a motherboard replacement.

You made analysis far more difficult by discussing things such as the keyboard lights. Keyboard, disk drives, etc all separate computers. Those computers do nothing to impede the main (motherboard) computer. Their actions mean nothing because the meter reported the only important fact.

The fact that the speaker did not beep means the CPU (or an adjacent function) is not operating.

Now, for that pci status board. Hopefully you always disconnected the AC power cord before installing or removing that board. Go back to what you saw on the purple wire. It was always 5 volts both before and after power switch was pressed. If you installed or removed anything when that purple wire had power, then you might have causes hardware damage. That caution even applies to the PCI status board. Always disconnect power cord before installing or removing any computer part or peripheral card. Another thing learned from those multimeter voltages.

Assuming the PCI status board is working, it would have posted some numbers as soon as the CPU starting executing. No numbers? Either that board was defective or it confirms what the speaker reported - CPU was never executing even after told to do so by the power supply controller.

Maybe search the internet for others whose HP Pavilion a6437c was disassembled in the computer junk yard - get that used motherboard.

Appreciate how much information was only in those six voltages (and why all that other information only made learning even more difficult). It took almost forever to get useful numbers. Excessively complicated by reading what others posted, listing pin numbers (which only confused everything), providing other useless voltages, discussing fan and describing keyboard and disk drive lights.

Also notice a fast analysis by disconnecting nothing until the very end (and then only the memory boards).

Westom can you please advise if my power supply voltage is OK:

Power on: Start - up:
Wire: Voltage: Voltage:

Purple 0.00 0.10
Green 0.00 0.73
Gray 0.00 0.88
Red 0.00 0.86
Yellow 0.00 3.58
Orange 0.00 0.41

 

[louis309]

Westom can you please advise if the following information is a good power supply?

Power on: Start up:
Wire: Voltage Voltage

Purple 0.00 0.10
Green 0.00 0.73
Gray 0.00 0.88
Red 0.00 0.86
Yellow 0.00 3.58
Orange 0.00 0.41

 

[jgildert]

Hi Guys, this is Just a quick message, something else for you to try.

Using a small screwdriver, physically "close" the metal "Clips" in all the pins on the Nylon Connector for the Mobo and CPU, WITHOUT mashing them up or closing them too much.

If there isn't a good circuit where the two pieces of metal "lock" together, you will have no end of problems and the junction can BURN out.

I've experienced this on a P4 self build a while back. When I removed the Square 4-Pin connector for the CPU power, it was burnt out.

Also, it happened to me today, I was looking at some cold Cathode lamps (IN A PC) which looked like they were failing. Twiddling with the wires made them start SMOKING! (This is due to a bad connection which causes high resistance and lots of heat!!)

Moral of the story, I closed up the 2 Metal Holed by pressing a screwdriver in to ensure a good connection and hey presto, NO smoke, and the Xold Cathode lamps were running at full brightness!