Why would pins 3 & 100 on a DDR DIMM fry?

What else but lightning or some kind of surge damage?

Could the socket have been swapped from another computer?

Mark Z.

Someone probably managed to put it in backwards at an angle. Then, on power on the traces vaporized. I have a couple of PC133 256MB that have the same problem(different pins). They still work fine because there are multiple gnd and vcc pins.....Paul

Nice idea, but it doesn't quite fit the circumstances.

The burned positions on the DIMM match the correct positions on the socket, and those positions are also burned. If it fried when it was put in backwards, then they shouldn't match.

Here's another clue that may help: someone was apparently trying to install more memory into the computer when this happened. (When I got the computer back, there was only the single module, though.)

Maybe the additional module somehow caused power to be fed back through those two pins on the existing module?

Odd but will we ever know now?

I don't know the answer, if that's what you mean.

I was hoping some smart people here could help me understand what happened.

I had sold this computer to somebody. It was working fine. The person I sold it to said she took it to a friend to install more memory. They say that it fried before they fooled with it. I don't believe them.

Not that it really matters now, but I really would like to understand what happened.

There are many kinds of voltages, used for memory. Some computers, such as the one I am using now takes both PC133 SDRAM or 266mHz (DDR RAM). The voltages are different and if you put SDRAM voltage on DDR RAM, you will burn it out.

Since the DDR RAM and SDRAM use slightly different sockets, it's usually not an issue.

The motherboard is "SMART", it detects the type of RAM present and adjusts the voltage properly. HOWEVER if you put BOTH DDR and SDRAM in the computer at the higher voltage is used on both sockets, burning out the DDR RAM.

If you look at the manual for the motherboard, you will see it.

If this is the case, someone tried to use both types at the same time and damaged the motherboard and the memory. If it was you, then they are right. If it was not ........

Geoff.

Unregistered ha escrito:

Probably they tried to install more memory with the computer turned on, or they turned on the computer by accident while they were installing the DIMM.

an

I don't believe you are correct. DDR DIMM sockets have a little bump in the middle, the exact position of which is placed according to the required voltage of the DIMM module. In fact, the DIMM socket has "2.50V" stamped into it next to the bump. Only 2.5V DIMMs should fit into this socket, or else the bump in the socket won't line up with the notch in the DIMM.

I sold the computer with a single DIMM in it, and it was working fine. It did not have a problem until the customer's friend started fooling with it.

Here's my reference regarding the voltage:

Still unexplained is why the two GROUND pads/contacts fried.

I would guess that a short occurred somewhere on the DIMM. It could have been a ceramic cap that shorted, or possibly a short between layers of the board. Maybe a foreign object like a screw hit the DIMM. This caused the pins closest to the short to burn. Since there are lots of Vcc and ground pins, it could still work as long as the short is either no longer present, or was removed from the circuit when the right traces melted. Andy Cuffe

snipped-for-privacy@gmail.com

I looked again carefully at the parts involved, and I discovered that my original analysis was incorrect.

The DIMM was inserted backwards.

Mystery solved (as far as I care).

Thanks to those who offered suggestions.

Unregistered wrote in news:642dnbeCS4mWom_ZnZ2dnUVZ snipped-for-privacy@comcast.com:

You can insert them backwards? I know the 168-pin type is keyed so you cannot insert them backwards. (Notches about 10% and 60% distance from the end.)

Puckdropper

I know people who can insert anything into anything else in any orientation - usually except the correct one.

That's correct, you can not put them both in the same socket. My point, which obviously I did not fully explain, is that some motherboards have BOTH DDR DIMM and SDRAM DIMM sockets.

SDRAM DIMMs are 3.3 volt, DDR DIMMs are 2.5 volt. On motherboards that have BOTH, if there is SDRAM in a socket, the voltage on BOTH sets of sockets is 3.3 volts. It's poor design, but they all do it.

That's pretty normal. Almost everyone has a friend who should not be allowed to touch a computer, but thinks they know everything.

He probably had hit the power button and put the computer in "sleep" mode, without actually turning it off or unplugging it.

Geoff.

The 184 DDR DIMMs are also keyed so you "can't" insert them backwards.

I imagine that one side was fully plugged in and the other side wasn't. Perhaps the motherboard was bowed out in the middle where the key wasn't going into the notch. I don't know.