DDR RAM Burnt when comp turned on. same 2 contacts !

[jameshanley39]

I put DDR RAM module into my socket, and when I turned the computer
on, 2 of the contacts got burnt. I think it's 184 pin RAM and it's
pin/contacts 86 and 78. That is the 8th and 16th contact counting
from the 93rd contact towards the first. Interestingly, on a diff
make/model of mobo, diff make ram , diff PSU, I had the same problem.
the exact 2 same contacts got burnt.

The events before, were, i restarted the comp (via windows) and it
reset but wasn't starting. I took a (the only) RAM module out. put it
the other socket, and it was fine.

THen i restarted through windows, and it reset but wouldn't start. I
unplugged te power. took the RAM out of the socket put it back in hte
same socket. turned on the power. switched it on, and hey presto, i
smelt burning and saw my ram module had burnt out.

anybody got any ideas what the problem is, how to diagnose?
I know i'm going to h ave to take the mobo back. But, this has happened
once before and ideally i really want to be able to detect a problem
like this before it hits and takes out my RAM too. I want to at least
detect what caused the problem.

It may be of interest, I tested the Voltages coming out the ram
sockets with a multimeter (could i have electricuted myself from
that? e.g. if a current surge caused the problem)
On a working board of the same kind , I got voltages of 2.6v and 1.3v,
depending on which contact i touched.
On the now screwed up board with the no doubt partially burnt socket I
got voltages of 0vv often and sometimes 0.3v . So not suprisingly,
the mobo seems buggered, but this is of course after the event.

I spoke to a guru electrician, he said maybe i could check a capacitor
with a 'good LCR meter'. And he said a multimeter won't pick up a PSU
swurge because it's all in the switching, and it's so fast the
multimeter wouldn't pick it up. he said i'd need an oscilloscope.
Well, i'm not electronics guru.
But you are RAM gurus

I'm thinking maybe you chip, MOBO and RAM specialists gurus and experts
have some idea of what happened, it was *the exact same 2 contacts *
that got burnt as on a diff comp i once had! So this must be a standard
prob. And that last time they burnt when I tried to turn it on. So,
v. similar to this time round.

 

[George Macdonald]

I put DDR RAM module into my socket, and when I turned the computer
on, 2 of the contacts got burnt. I think it's 184 pin RAM and it's
pin/contacts 86 and 78. That is the 8th and 16th contact counting
from the 93rd contact towards the first. Interestingly, on a diff
make/model of mobo, diff make ram , diff PSU, I had the same problem.
the exact 2 same contacts got burnt.

93rd? There are 92 pins and pins 85 and 77 are Vdd & Vddq respectively.

The events before, were, i restarted the comp (via windows) and it
reset but wasn't starting. I took a (the only) RAM module out. put it
the other socket, and it was fine.

THen i restarted through windows, and it reset but wouldn't start. I
unplugged te power. took the RAM out of the socket put it back in hte
same socket. turned on the power. switched it on, and hey presto, i
smelt burning and saw my ram module had burnt out.

anybody got any ideas what the problem is, how to diagnose?
I know i'm going to h ave to take the mobo back. But, this has happened
once before and ideally i really want to be able to detect a problem
like this before it hits and takes out my RAM too. I want to at least
detect what caused the problem.

It may be of interest, I tested the Voltages coming out the ram
sockets with a multimeter (could i have electricuted myself from
that? e.g. if a current surge caused the problem)
On a working board of the same kind , I got voltages of 2.6v and 1.3v,
depending on which contact i touched.
On the now screwed up board with the no doubt partially burnt socket I
got voltages of 0vv often and sometimes 0.3v . So not suprisingly,
the mobo seems buggered, but this is of course after the event.

I've no idea what to expect on those pins if the slot is empty, i.e. no
power-on sequence has happened.

I spoke to a guru electrician, he said maybe i could check a capacitor
with a 'good LCR meter'. And he said a multimeter won't pick up a PSU
swurge because it's all in the switching, and it's so fast the
multimeter wouldn't pick it up. he said i'd need an oscilloscope.
Well, i'm not electronics guru.
But you are RAM gurus

I'm thinking maybe you chip, MOBO and RAM specialists gurus and experts
have some idea of what happened, it was *the exact same 2 contacts *
that got burnt as on a diff comp i once had! So this must be a standard
prob. And that last time they burnt when I tried to turn it on. So,
v. similar to this time round.

Check the electrolytic capacitors on the mbrd for swelling tops or leakage
near the base. There was a slew of mbrds a couple of years ago which had
bad caps: http://www.niccomp.com/taiwanlowesr.htm. For examples:
http://www.badcaps.net/ & http://www.motherboardrepair.com/.

 

[jameshanley39]

93rd? There are 92 pins and pins 85 and 77 are Vdd & Vddq respectively.


I've no idea what to expect on those pins if the slot is empty, i.e. no
power-on sequence has happened.


Check the electrolytic capacitors on the mbrd for swelling tops or leakage
near the base. There was a slew of mbrds a couple of years ago which had
bad caps: http://www.niccomp.com/taiwanlowesr.htm. For examples:
http://www.badcaps.net/ & http://www.motherboardrepair.com/.

--

Thanks, you got it, it is pins 85 and 77, VDD and VDDQ respectively, as
you said.

the capacitors aren't leaking or bulging or tilting.

So, the prob is still undiagnosed, and i'm not sure how i'd avoid or
detect and prevent it from happening in the future.

The RAM module whose 2 contacts got burnt had chips made by Infineon.
I have heard they're a decent make of chip.

On my old system where the samae thing happened, I think the RAM module
cheap, like RAM BO or RAMBO RAM .

The RAM was seated fine.

I don't know if iti's bad RAM, bad MOBO or bad PSU or bad AC/Mains

I'm sure this has happened to more ppl, since it has happened to me
twice. Hopefully, next time it happens, people will put the incident
on usenet! At least this post comes up for burnt ram , with the given
pins. It's a start!

 

[George Macdonald]

Thanks, you got it, it is pins 85 and 77, VDD and VDDQ respectively, as
you said.

the capacitors aren't leaking or bulging or tilting.

So, the prob is still undiagnosed, and i'm not sure how i'd avoid or
detect and prevent it from happening in the future.

The RAM module whose 2 contacts got burnt had chips made by Infineon.
I have heard they're a decent make of chip.

The DRAM chips themselves would not likely be suspect here at all - if
anything the DIMM and its ancillary components might.

On my old system where the samae thing happened, I think the RAM module
cheap, like RAM BO or RAMBO RAM .

AFAICT RAMBO, or RAM BO is a brand name used by a DIMM & other memory
product, mfr called Muse in Hong Kong - never heard of them before but I
tend to stay with mainstream mfrs, usually Crucial. Back in the PC-100
days, you used to be able to get away with generic DIMMs but this is no
longer the case IMO - the specs are so tight on DDR-DRAM that it's not
worth the risk.

The RAM was seated fine.

I don't know if iti's bad RAM, bad MOBO or bad PSU or bad AC/Mains

Whatever failed I'd have thought all modern mbrds would/should have
over-voltage and over-current threshold protection against this kind of
thing but I'm no expert. No sign of blistering or burnt traces on the
mbrd? Was this a mainstream mfr mbrd?

I'm sure this has happened to more ppl, since it has happened to me
twice. Hopefully, next time it happens, people will put the incident
on usenet! At least this post comes up for burnt ram , with the given
pins. It's a start!

First I've heard of this kind of incident around here.

 

[jameshanley39]

The DRAM chips themselves would not likely be suspect here at all - if
anything the DIMM and its ancillary components might.


AFAICT RAMBO, or RAM BO is a brand name used by a DIMM & other memory
product, mfr called Muse in Hong Kong - never heard of them before but I
tend to stay with mainstream mfrs, usually Crucial. Back in the PC-100
days, you used to be able to get away with generic DIMMs but this is no
longer the case IMO - the specs are so tight on DDR-DRAM that it's not
worth the risk.


Whatever failed I'd have thought all modern mbrds would/should have
over-voltage and over-current threshold protection against this kind of
thing but I'm no expert. No sign of blistering or burnt traces on the
mbrd? Was this a mainstream mfr mbrd?

1st time it happened: PCCHIPSUSA motherboard and RAM BO RAM. PSU was
a standard Antec PSU (I think) which I still use.

2nd time it happened: Asus motherboard P4P8T MBRD (ASus T2 'barebones'
system - RAM was from an old ASus T2 that had 1 and later 2 bad IDE
connectors!
The RAM in the old Asus T2 system which I reused, was not supplied by
Asus. THe details on it are

P/N PCM-RAM-D33F512S <-- written on a yellow sticker with a barcode
on it.

and the chips say Infineon on them.

I don't know who made the module. But I guess they were good enough to
put Infineon chips on it.

Regarding voltage protection. IT may have had voltage protection. The
comp was working fine, I wanted to restart it just to confirm that the
CPU temperature wasn't going past 50 degrees. So I restarted it and it
reset but didn't start up. blank screen. Maybe that was voltage
protection. When I unplugged it and put the RAM Back in, maybe it
'forgot' that the voltage (or current?) was too high, and it blew. I
wouldn't know te electronics behind it.

BTW, is it possible that high current did it? I will be checking RAM
sockets next time a computer resets but start up or beep or post.
So, I would like to know if i'd injure myself testing the voltage,
maybe i'd get a high voltage or current through me.
The Modules 2 'power supply pins' Vdd and VddQ are totally browned.
Can switching PSUs get surges that high? 'cos if so, i shuldn't be
testing connectors with a multimeter at all.

thanks

 

[Johnno]

93rd? There are 92 pins and pins 85 and 77 are Vdd & Vddq
respectively.

If you are counting from a pin marked 93, then I suspect you are actually
looking at pins 100 and 108, which are Vdd and Vss.
These are a much more likely pair to get burnt, since Vdd and Vddq should
be the same voltage. As to why, it's more difficult to know. I don't want
to suggest you put it in the wrong way round, but it is just about possible
to make contact if you do, and might well lead to the consequences you
describe.

 

[George Macdonald]

George Macdonald wrote:

1st time it happened: PCCHIPSUSA motherboard and RAM BO RAM. PSU was
a standard Antec PSU (I think) which I still use.

2nd time it happened: Asus motherboard P4P8T MBRD (ASus T2 'barebones'
system - RAM was from an old ASus T2 that had 1 and later 2 bad IDE
connectors!
The RAM in the old Asus T2 system which I reused, was not supplied by
Asus. THe details on it are

P/N PCM-RAM-D33F512S <-- written on a yellow sticker with a barcode
on it.

No trace of that anywhere.

and the chips say Infineon on them.

I don't know who made the module. But I guess they were good enough to
put Infineon chips on it.

Regarding voltage protection. IT may have had voltage protection. The
comp was working fine, I wanted to restart it just to confirm that the
CPU temperature wasn't going past 50 degrees. So I restarted it and it
reset but didn't start up. blank screen. Maybe that was voltage
protection. When I unplugged it and put the RAM Back in, maybe it
'forgot' that the voltage (or current?) was too high, and it blew. I
wouldn't know te electronics behind it.

BTW, is it possible that high current did it? I will be checking RAM
sockets next time a computer resets but start up or beep or post.
So, I would like to know if i'd injure myself testing the voltage,
maybe i'd get a high voltage or current through me.
The Modules 2 'power supply pins' Vdd and VddQ are totally browned.
Can switching PSUs get surges that high? 'cos if so, i shuldn't be
testing connectors with a multimeter at all.

You shouldn't get injured by testing voltage on the mbrd; if you opened a
powered-off P/S unit quickly enough and got a hold of one of the capacitor
contacts before it bled its charge of you might get a jolt but you'd have
to be quick.

I'm not sure how the voltage control works -- maybe someone else can
comment here -- other than that there's a power control circuit, usually on
an IC, the ISL6559 on my mbrd, which controls the MOSFET drivers for the
DC-DC conversion. I wouldn't think any surge at the Power Supply could get
through to the DRAM power lines but again, maybe someone else can comment.

 

[Franc Zabkar]

I'm not sure how the voltage control works -- maybe someone else can
comment here -- other than that there's a power control circuit, usually on
an IC, the ISL6559 on my mbrd, ...

That appears to be used in the CPU's Vcore supply:

http://www.intersil.com/data/an/an1132.pdf
http://www.intersil.com/data/fn/fn9084.pdf

... which controls the MOSFET drivers for the
DC-DC conversion. I wouldn't think any surge at the Power Supply could get
through to the DRAM power lines but again, maybe someone else can comment.

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

 

[George Macdonald]

That appears to be used in the CPU's Vcore supply:

http://www.intersil.com/data/an/an1132.pdf
http://www.intersil.com/data/fn/fn9084.pdf

Yeah well my CPU is an Athlon64 which is a different animal - memory
DC-DC is done in the CPU die AFAIK.