How to detect a dead CPU?

[ck26]

As I've got a pending problem that is being discussed in another thread that
may be related to the above, I wanted to ask more generally in this seperate
thread: how can you tell if a CPU has died?

 

[FD]

As I've got a pending problem that is being discussed in another thread that
may be related to the above, I wanted to ask more generally in this seperate
thread: how can you tell if a CPU has died?

In general - replace it with another and if your PC works , its dead.

 

[ck26]

In general - replace it with another and if your PC works , its dead.

Really?! - there's no guide other than to splash out on a new CPU, hoping
that its not a waste of money? Surely you jest...

 

[Vanguard]

You don't mention if it is by itself and you're just looking at it or if
it is inserted into a motherboard. If in your hand, you can't tell
unless, like for an AMD, it got burned up because the heatsink came off
it. If in a motherboard, the BIOS text and/or beep codes should
indicate a bad CPU; see http://www.bioscentral.com.

 

[user]

Really?! - there's no guide other than to splash out on a new CPU, hoping
that its not a waste of money? Surely you jest...

Really! Unless you have a scope so that you can check the address/data
buses and other points on the processor, it is difficult to ascertain if
the processor is even trying to work. As another poster stated, if you
get bios error indications (beeps) you can be assured that at least SOME
of the functions are working.

Ken

 

[Phrederik]

In general - replace it with another and if your PC works , its dead.

....or put the questionable CPU into another system to test it.

 

[ck26]

You don't mention if it is by itself and you're just looking at it or if

it is inserted into a motherboard. If in your hand, you can't tell
unless, like for an AMD, it got burned up because the heatsink came off
it. If in a motherboard, the BIOS text and/or beep codes should
indicate a bad CPU; see http://www.bioscentral.com.

OK, its in situ - but I'm not getting any beeps at all. What, if anything
does that mean for the CPU? I guess the bios beeps _after_ the CPU starts
working, so does an absence of bios beeps mean that the CPU is _not_
working - I'm getting no boot / no video.

 

[~misfit~]

OK, its in situ - but I'm not getting any beeps at all. What, if anything
does that mean for the CPU? I guess the bios beeps _after_ the CPU starts
working, so does an absence of bios beeps mean that the CPU is _not_
working - I'm getting no boot / no video.

Try taking the CPU out and see if you get error beeps when you attempt to
boot.

 

[ck26]

Try taking the CPU out and see if you get error beeps when you attempt to

boot.

The same - no beeps. Is that indicative that the motherboard is faulty? Or
does it narrow it down to anything else?

As I'm so unsure - I've taken some images of the CPU itself as I'm really
not sure what it would look like if it had burned out. What is the general
consensus - are these burn marks or valid glue / discoloration marks?

CPU Top: http://www33.brinkster.com/ck26/cpu/DSC00001a.jpg
CPU Bottom: http://www33.brinkster.com/ck26/cpu/DSC00002a.jpg
Heatsink thing(don't actually know what its called - the thing that sits
directly on the CPU:
http://www33.brinkster.com/ck26/cpu/DSC00003a.jpg

Socket: http://www33.brinkster.com/ck26/cpu/DSC00004a.jpg

 

[kony]

The same - no beeps. Is that indicative that the motherboard is faulty? Or
does it narrow it down to anything else?

As I'm so unsure - I've taken some images of the CPU itself as I'm really
not sure what it would look like if it had burned out. What is the general
consensus - are these burn marks or valid glue / discoloration marks?

CPU Top: http://www33.brinkster.com/ck26/cpu/DSC00001a.jpg
CPU Bottom: http://www33.brinkster.com/ck26/cpu/DSC00002a.jpg
Heatsink thing(don't actually know what its called - the thing that sits
directly on the CPU:
http://www33.brinkster.com/ck26/cpu/DSC00003a.jpg

Socket: http://www33.brinkster.com/ck26/cpu/DSC00004a.jpg

The CPU may not be working, but that does NOT mean it's dead,
necessarily, or usually. As another poster mentioned it could easily
be the motherboard.

In the previous thread you mentioned a burning smell, right? If it
was the CPU getting THAT hot, it would have noticable, visual hints...
anywhere from significant discoloration to warpage, charring, peeling
of the top, or a dark spot underneith. When a CPU frys quickly
there's not necessarily as much visual damage, but from your account,
the smell, whatever happened didn't happen that quickly. The pictures
didn't show anything remarkable, out of the ordinary.

I still think it's the power supply, or next most-likely the
motherboard. If you examine the components under a strong light,
sometimes it can help to see what was burning.


Dave

 

[DaveW]

Replace it with a different one and see if that fixes the computer. Process
of elimination.

 

[Vanguard]

No video? Its BIOS is supposed to load so you can see the motherboard's
BIOS version, the result of a memory check, hardware info like CPU
speed, what drives were detected or hard configured in the mobo BIOS,
show the table of hardware devices (I forget what that table is called),
and eventually will beep once to let you know the POST has completed.
If you have no video at all, a defective video card whose BIOS won't
load will kill the POST right away. Yank out the video card and you
should get, I think, 1 long beep and 2 short beeps (for Award BIOS).

Do you have any memory installed?

You sure you have an onboard speaker or the external speaker is
connected to the 2-pin header on the motherboard so you can actually
hear the beeps?

See http://www.pcguide.com/ref/mbsys/bios/boot.htm for the boot
sequence.

Do you see the LEDs flash on the keyboard? That's due to the reset
signal.

 

[~misfit~]

The same - no beeps. Is that indicative that the motherboard is faulty? Or
does it narrow it down to anything else?

Just a test to see if the mobo is working properly or if the CPU is stuffed.
If it had beeped with no CPU I'd say that pointed to the CPU being the
problem. As it didn't then it didn't really tell us anything one way or the
other.

As I'm so unsure - I've taken some images of the CPU itself as I'm really
not sure what it would look like if it had burned out. What is the general
consensus - are these burn marks or valid glue / discoloration marks?

CPU Top: http://www33.brinkster.com/ck26/cpu/DSC00001a.jpg
CPU Bottom: http://www33.brinkster.com/ck26/cpu/DSC00002a.jpg
Heatsink thing(don't actually know what its called - the thing that sits
directly on the CPU:
http://www33.brinkster.com/ck26/cpu/DSC00003a.jpg

Socket: http://www33.brinkster.com/ck26/cpu/DSC00004a.jpg

Nothing obviously wrong there.

 

[Phrederik]

The same - no beeps. Is that indicative that the motherboard is faulty? Or
does it narrow it down to anything else?

No CPU = No beeps...

HOW can the BIOS run to make the beeps if there is no CPU to run the BIOS
code?

 

[ck26]

In the previous thread you mentioned a burning smell, right? If it

was the CPU getting THAT hot, it would have noticable, visual hints...
anywhere from significant discoloration to warpage, charring, peeling
of the top, or a dark spot underneith. When a CPU frys quickly
there's not necessarily as much visual damage, but from your account,
the smell, whatever happened didn't happen that quickly. The pictures
didn't show anything remarkable, out of the ordinary.

Thanks Dave and those of you who have taken a look. I guess then that the
CPU may still have a chance of being alive, but its not certain one way or
the other at the moment.

I still think it's the power supply, or next most-likely the
motherboard. If you examine the components under a strong light,
sometimes it can help to see what was burning.

I've taken everything out bit by bit and inspected them all under strong
light (I've taken the power supply apart too) and nothing shows any visible
signs of burn out / damage. The memory chips are fine - I know what burnt
out memory modules look and smell like. The motherboard's capacitors, and
other components all "look" fine. I guess looking fine and being fine may be
the hardest difference to detect. I haven't had a chance to go to a hardware
store for a voltmeter or to get a new power supply, so maybe this weekend,
I'll solve this mystery once and for all. I was just hoping I could avoid
spending any money on trying to detect what is wrong, just in case I need to
spend that money on a new machine.

Thanks all for your efforts, much appreciated.

 

[ck26]

No CPU = No beeps...

HOW can the BIOS run to make the beeps if there is no CPU to run the BIOS
code?

I did think that and say that before I tried it, but hey, I'm desperate to
solve this!

 

[ck26]

If you have no video at all, a defective video card whose BIOS won't

load will kill the POST right away. Yank out the video card and you
should get, I think, 1 long beep and 2 short beeps (for Award BIOS).

OK, I'll try that tonight. Thanks.

Do you have any memory installed?

Yes, and I'm sure the two modules are fine - I inspected them both for
scorch marks / smell.

You sure you have an onboard speaker or the external speaker is
connected to the 2-pin header on the motherboard so you can actually
hear the beeps?
Yup..

Do you see the LEDs flash on the keyboard? That's due to the reset
signal.

Hee hee, I have a cordless keyboard and mouse! I could try plugging a
"standard" one in though. Thanks for the tip.

 

[Phrederik]

Well... if there was a smell when it died, the part should still smell.

Run your NOSE around the parts in question and see if you can find the
burnout that way.

....one stupid question...

Any chance that the MONITOR burned out and your PC is booting fine and you
just can't see it???

 

[kony]

I was just hoping I could avoid
spending any money on trying to detect what is wrong, just in case I need to
spend that money on a new machine.

A cheap $5 voltage meter will suffice for the level of accuracy needed
to do simple testing of the power supply, and it's very handy to have
one in general.

Buy replacement parts that will accomodate future upgrades, so there
isn't any significant money wasted, you'll be on your way towards a
faster system still.


Dave

 

[ck26]

Run your NOSE around the parts in question and see if you can find the

burnout that way.

Hmm, I'm no pervert, but OK, here goes... Nope - everything has a vague
electrical smell - particularly the heatsink. But I'm sure that's
normal-ish.

...one stupid question...

Any chance that the MONITOR burned out and your PC is booting fine and you
just can't see it???

That thought had crossed my mind - I have switched monitors and I can rule
that out for sure now.