Sign in with
Sign up | Sign in
Your question
Solved

Computer Randomly Died won't power on.

Last response: in Motherboards
Share
December 13, 2011 8:24:40 AM

Hey guys, I was on the computer yesterday when it just died. It was instant, like someone unplugged the board. When I pushed the power button I got nothing I reached in the case and felt for hot-spots and nothing seemed abnormal so I turned off the PSU for a few min and came back to it. Turning on the PSU I got the green light on the board but when I push power I get less than 1/2 a second of life out of it and then it quits. After every attempt of the items below I got the same result when plugging in the PSU and pushing power.
Things I have tried,

0) ensuring all connections were firm
1) swapping out the PSU for a known working one
2) swapping out the CPU
3) Swapping out the video card (running out of ideas)
4) swapping out the ram (becoming certain its the board)
5) pulled the board to examine it... I could not see any trace of burns, scrapes, shorts, swollen or discolored capacitors... I really don't know what else I am looking for. I know this board seems antique-dated to many but it has served me well and I am quite fond of it.

6) I heard something about CPU dies being pressure sensitive so the boards will not boot without a heat sink should I try giving my heat sink tensioner a tweak? I remembered wrong its will not boot without a working Heat Sink Fan.

Asus A8N-SLI board, FX60 processor(2.7 GHz unlocked dual core), NV 9series card and 4 gb of g-skill ram.
a b Ĉ ASUS
a c 156 V Motherboard
December 13, 2011 8:48:04 AM

#6. Never heard that.

What are the two PSU's that you have tried?

While your system is apart ...

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.
http://www.tomshardware.com/forum/262730-31-breadboardi...

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:

Check for line power at the PSU input. Extension cords, power strips, and power cords do fail.

If you have power and no beeps, suspect components in likely order are PSU, motherboard, and CPU.

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.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

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.
m
0
l
December 13, 2011 11:25:05 PM

#6 I remembered wrong, its the HSF not the HS

I've been running the Zalman ZM500-HP for a few years. (500w) and the alternate I tried was a Mad Dog 450w (Spire)
Both PSUs power my spare board fine. But my 64 bit OS won't work on the spare board :( 

Bread board style I have MoBo power plug, CPU power plug, PSU plugged, CPU, HSF, speaker...
1/2 second or less of power, no beep. Tried 2 different power cords, no extensions were used.
The speaker tested fine on the spare board.

I really think its the board I just wish I could identify the component that failed so I can solder in a replacement, If applicable (thinking caps...)

I'm gonna poke around some more Thanks for posting hopefully I figure something out.
m
0
l
Related resources
December 14, 2011 1:00:52 AM


Did more tinkering, Randomly it after moving it around it would power on an off like normal.
Could this be a weak solder joint that touches when bumped or something else being temperamental?
m
0
l

Best solution

a b Ĉ ASUS
a c 156 V Motherboard
December 14, 2011 9:16:07 AM

Poor solder joint more than likely. The problem will be finding it.
Share
December 14, 2011 9:24:21 AM

jsc said:
Poor solder joint more than likely. The problem will be finding it.


Yeah, I pulled the mounting hardware for the Heat sink and saw that it had flattened out some solder joints (visibly weak) around the CPU. I heated them up and added a little solder to them (some of them) jeez they are so small in that area! I cut a thin piece of cardboard to fit in there as a cushion when I put it back together. I'm getting normal power cycling more often now but still not enough to put it back into use. She had a good run, I think it may just be time to look at similar replacement or upgrades.
m
0
l
December 16, 2011 7:36:53 AM

Best answer selected by ghkj21.
m
0
l
December 16, 2011 7:49:43 AM

Well I decided to throw in the towel and just buy a modern board and processor. (my 2 939 processors will be on ebay soon)

I ordered the ASRock 970 Extreme 3 MoBo and had a toss up between the AMD FX 6100 3.3GHz 6 core and the Phenom II x4 970 Black Edition 3.5GHz 4 core. They were both the same price and I chose the Phenom in the end as I heard the FX series only shines when you are exclusively Multi-threading. Hope I chose right there...

I also for kicks threw my 939 board in the oven to try a in house re-flow. turns out my oven is over 25 degrees hotter than the dial says and one of the CAPs exploded and the shock wave lifted a microchip off of its wet solder joints. The rest of the board looked good every connection looked like new again but I'm willing to bet all the CAPs are bad now.
m
0
l
!