From: Yousuf Khan on
Ant wrote:
> On 3/8/2010 8:49 PM PT, Robert Redelmeier typed:
>
>> As Yousef has mentioned, any PSU failure serious enough to
>> damage RAM could easily damage the CPU. Especially AMD with
>> the RAM controller and busses inside the CPU.
>
> Damn. Intel CPUs does better with this?

The old ones might, because they had separated memory controllers on the
chipset rather than inside the processor. But the new ones, Core
i-series, are exactly like AMD ones, they have integrated memory
controllers too.

However, I don't see this as an issue in your case, whether it was
separated or integrated memory controllers. The TLB is part of the
processor's cache system, which is much higher up in the food chain than
the memory controllers. They don't have any direct connection to the
system RAM.

Yousuf Khan
From: Yousuf Khan on
Ant wrote:
> On 3/8/2010 7:01 PM PT, Yousuf Khan typed:
>
>> If that PSU failure took out so much other hardware, then it's likely it
>> took out your processor too, and it took longer for it to finally fail.
>> CPU chips tend to be more robust than memory chips and GPU chips, a lot
>> more redundancy, so they may show the signs of the failure much later.
>
> Ah, that could be it. So far, a 512 MB of RAM and video card went bust
> with the PSU. Too bad my friend and I did not see physical evidences of
> busted caps, discolorations, etc. :(

Those may yet come, after much time. But in reality, caps can be much
more robust than any of the electronic components. The CPU and RAM may
run anywhere between 1.0 to 2.0 Volts, so a spike of even 0.1V is
significant to them. A capacitor is just a very simple electrical
component, and a small spike won't kill it. A damaged capacitor might
still continue to work in diminished capacity for a long time.

In actual fact, the motherboard capacitors are there to protect against
voltage spikes to some extent. So the fact that it didn't really protect
these components, might be an indication that they may already be
damaged and just working in diminished capacity right now.

Your original PSU problem, what caused it? Lightening? Or did it just go
on its own for some unknown reason? If it went on its own, then it's
likely it caused this level of damage to your entire system. The PSU
also has capacitors in it, designed to protect against voltage spikes. A
surge suppressing power bar also helps protect along the way, with
capacitors. Each one acts like a flood dike. A lightening strike may
overwhelm the surge suppressor, and then it will overwhelm the PSU, but
the PSU has fuses that will sacrifice themselves and thus protect the
motherboard and internal components. If the PSU didn't do that fast
enough, then it may have let over-voltage through.

Or possibly, the PSU itself was the cause of the overvoltage. Was it an
old PSU that failed? Certain PSU size calculator sites make a provision
for systems that are left on for 24 hours for years on end. They reduce
its capacity rating by upto 40% for such a situation!

Yousuf Khan
From: Robert Redelmeier on
Ant <ant(a)zimage.comant> wrote in part:
> 40 times?! Is there an easy way to run it in one command
> or something? I had to run two of them manually earlier. :(

Type once, repeat many times:
$ time nice -19 ./burnMMX P &

then just [up-arrow] [enter] to repeat.


> OK, I am fine to 40 but I don't want to manually copy
> and paste 40 times. :(


Why not? That's even easier -- just highlight the whole line
(including the return) then click the middle button 40 times.

-- Robert

From: ANTant on
> Your original PSU problem, what caused it? Lightening? Or did it just go
> on its own for some unknown reason? If it went on its own, then it's
> likely it caused this level of damage to your entire system. The PSU
> also has capacitors in it, designed to protect against voltage spikes. A
> surge suppressing power bar also helps protect along the way, with
> capacitors. Each one acts like a flood dike. A lightening strike may
> overwhelm the surge suppressor, and then it will overwhelm the PSU, but
> the PSU has fuses that will sacrifice themselves and thus protect the
> motherboard and internal components. If the PSU didn't do that fast
> enough, then it may have let over-voltage through.

Here is what I remember before the PSU went dead.

1. A few days before it, I smelled something burning but couldn't figure
out what.

2. A few laters, computer went dead. Computer didn't want to boot up.
Drive light blink like crazy when computer is on.

3. My friend and I investigated and narrowed down to dead PSU. However,
computer still wouldn't boot up. We tried another SAME motherboard
model. Same thing. We tried an older motherboard with an Athlon 754
single core CPU. No problems!

4. After more testings, we found that EVGA GeForce 8800 GT was the
problem to prevent motherboard to boot up. That explains why motherboard
beeped a few times without it. With it, nothing. :/ We RMA'ed it and got
a fixed one.

5. Got everything back. Then, kernel panics one in a while (usually
takes 5-8 days to reproduce and usually during idle times from what I
noticed)! Note that I never had them before getting things back
together. I assume it was the PSU incident that started it.

6. We ran memtest86+ v4.00 and it found errors. My friend and I narrowed
down to a 512 MB piece and removed it. Tested all of them and no errors
again.

7. We assumed things were fine now after finding out the bad RAM. NOPE
after a week or so, more kernel panics! Reran memtest86 overnight twice
and no errors. Great, something else is wrong then.


> Or possibly, the PSU itself was the cause of the overvoltage. Was it an
> old PSU that failed? Certain PSU size calculator sites make a provision
> for systems that are left on for 24 hours for years on end. They reduce
> its capacity rating by upto 40% for such a situation!

The new Antec PSU? How can I check for that? I think I already shared my
machine specifications:
http://alpha.zimage.com/~ant/antfarm/about/computers.txt (secondary). If
not, then see that link. ;)

Also note that I have an UPS behind the computer (and another desktop).
--
"We are anthill men upon an anthill world." --Ray Bradbury
/\___/\
/ /\ /\ \ Phillip (Ant) @ http://antfarm.ma.cx (Personal Web Site)
| |o o| | Ant's Quality Foraged Links (AQFL): http://aqfl.net
\ _ / Please remove ANT if replying by e-mail.
( )
From: ANTant on
>> 40 times?! Is there an easy way to run it in one command
>> or something? I had to run two of them manually earlier. :(
>
> Type once, repeat many times:
> $ time nice -19 ./burnMMX P &
>
> then just [up-arrow] [enter] to repeat.

Wow, that's going to be crazy to count them :P. I assume killall burnMMX
command will kill them all. Does it have to be 40 of them? I might run
them all night tonight or so.


>> OK, I am fine to 40 but I don't want to manually copy
>> and paste 40 times. :(
>
>
> Why not? That's even easier -- just highlight the whole line
> (including the return) then click the middle button 40 times.

Still a lot. :) I will do that.
--
"We are anthill men upon an anthill world." --Ray Bradbury
/\___/\
/ /\ /\ \ Phillip (Ant) @ http://antfarm.ma.cx (Personal Web Site)
| |o o| | Ant's Quality Foraged Links (AQFL): http://aqfl.net
\ _ / Please remove ANT if replying by e-mail.
( )