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#1
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Burned DIMM pads
We put a bunch of computers into a large trade school, and we're getting
back DDR400 dimms with pins 184 and 181 burned off. We think these are being hot-swapped, and we're going to run some tests in a couple days to see if we can duplicate, but have any of you seen this before? -John O |
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#2
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Burned DIMM pads
JohnO wrote: We put a bunch of computers into a large trade school, and we're getting back DDR400 dimms with pins 184 and 181 burned off. We think these are being hot-swapped, and we're going to run some tests in a couple days to see if we can duplicate, but have any of you seen this before? -John O Not necessiarly deleberately hot swapped, but if you don't make sure that BOTH of the retaining clips are in, the stick may be angled, and if you're unlucky enough to have just the right (wrong) angle, you can zap them. That's where I'd put my first test. One of our newbie techs did that once. After that, we put a "no smoking" sign on his cubicle. I don't recall which pins were shorted but it WAS a perfectly good stick of PC133. But ther RAM stick was painfully hot afterwards. It was tossed, we also tossed the motherboard on general principals. |
#3
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Burned DIMM pads
wrote in message ups.com... JohnO wrote: We put a bunch of computers into a large trade school, and we're getting back DDR400 dimms with pins 184 and 181 burned off. We think these are being hot-swapped, and we're going to run some tests in a couple days to see if we can duplicate, but have any of you seen this before? -John O Not necessiarly deleberately hot swapped, but if you don't make sure that BOTH of the retaining clips are in, the stick may be angled, and if you're unlucky enough to have just the right (wrong) angle, you can zap them. That's where I'd put my first test. One of our newbie techs did that once. After that, we put a "no smoking" sign on his cubicle. I don't recall which pins were shorted but it WAS a perfectly good stick of PC133. But ther RAM stick was painfully hot afterwards. It was tossed, we also tossed the motherboard on general principals. Ahh, you're saying powered up but the stick isn't fully inserted? -John O |
#4
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Burned DIMM pads
JohnO wrote: wrote in message ups.com... JohnO wrote: We put a bunch of computers into a large trade school, and we're getting back DDR400 dimms with pins 184 and 181 burned off. We think these are being hot-swapped, and we're going to run some tests in a couple days to see if we can duplicate, but have any of you seen this before? -John O Not necessiarly deleberately hot swapped, but if you don't make sure that BOTH of the retaining clips are in, the stick may be angled, and if you're unlucky enough to have just the right (wrong) angle, you can zap them. That's where I'd put my first test. One of our newbie techs did that once. After that, we put a "no smoking" sign on his cubicle. I don't recall which pins were shorted but it WAS a perfectly good stick of PC133. But ther RAM stick was painfully hot afterwards. It was tossed, we also tossed the motherboard on general principals. Ahh, you're saying powered up but the stick isn't fully inserted? -John O Bingo. It'll either: a) Not work, and do no damage b) smoke the ram and/or motherboard Depending on luck, angles and motherboard design. You'll want to use the same motherboards as your trad shcool or you may not be able to reproduce. The pins on ram sticks are straight, so when they're tilted, it's possible to short across ajacent pins. Other shorts may be possible. THe one that smoked the last one had the thing tilted at a 5-10 degree angle. |
#5
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Burned DIMM pads
You can tell if the memory stick is not fully and correctly inserted on most
motherboard as the retaining clips at each end of the memory stick will not be in the fully upright position. Try removing a stick buy pushing back on the clips and then re-inserting and you'll know what I mean. JS "JohnO" wrote in message ... wrote in message ups.com... JohnO wrote: We put a bunch of computers into a large trade school, and we're getting back DDR400 dimms with pins 184 and 181 burned off. We think these are being hot-swapped, and we're going to run some tests in a couple days to see if we can duplicate, but have any of you seen this before? -John O Not necessiarly deleberately hot swapped, but if you don't make sure that BOTH of the retaining clips are in, the stick may be angled, and if you're unlucky enough to have just the right (wrong) angle, you can zap them. That's where I'd put my first test. One of our newbie techs did that once. After that, we put a "no smoking" sign on his cubicle. I don't recall which pins were shorted but it WAS a perfectly good stick of PC133. But ther RAM stick was painfully hot afterwards. It was tossed, we also tossed the motherboard on general principals. Ahh, you're saying powered up but the stick isn't fully inserted? -John O |
#6
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Burned DIMM pads
"JS" @ wrote in message ... You can tell if the memory stick is not fully and correctly inserted on most motherboard as the retaining clips at each end of the memory stick will not be in the fully upright position. Try removing a stick buy pushing back on the clips and then re-inserting and you'll know what I mean. The instructions to the students used to have good photos of that, and I'll have to check if they are still there (on the road today, Iron City). Good feedback guys, I appreciate it. -John O |
#7
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Burned DIMM pads
On Wed, 17 May 2006 11:05:29 -0400, "JohnO"
We put a bunch of computers into a large trade school, and we're getting back DDR400 dimms with pins 184 and 181 burned off. We think these are being hot-swapped, and we're going to run some tests in a couple days to see if we can duplicate, but have any of you seen this before? Tip: ATX "off" is NOT OFF - there's still power applied to the mobo! So you have to re-train users and techs who grew up with pre-ATX systems that now they have to unplug from mains, rather than simply switch off the PC case, before any open-case work. Also, note that DIMMs may differ in operating voltage. Usually the notches will be slightly offset so that you can't easily (say) plug in a 3.3V SDRAM DIMM into a 5V SDRAM slot. The second issue may be an issue if you have a mix of PCs that cross generations (e.g. old 5V Socket 7 SDRAM vs. newer PII/PIII) and folks try to redeploy RAM resources across the pool of PCs. If it doesn't easily fit, there's a *reason* :-) Do the burned DIMMs also have bruised or filed-open notches? -------------------- ----- ---- --- -- - - - - Trsut me, I won't make a mistake! -------------------- ----- ---- --- -- - - - - |
#8
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Burned DIMM pads
If it doesn't easily fit, there's a *reason* :-)
Do the burned DIMMs also have bruised or filed-open notches? No, these are a *lots* of identical systems built to our specs, and students are using our instructions for removing and then reinstalling the dimm. Unfortunately, these systems don't have power supply switches, making the removal of the power cable necessary--and I suspect not always accomplished. We do tell the students to make sure the light on the mobo is off. Looks like we have to stick a meter on those pins and see what's there when off/AC-attached. Of all those computers (~1k) we've had maybe ten burned dimms, so there's nothing *completely* wrong with the instrux or hardware. Problem is, the instructors don't know exactly what step was being performed when the smoke appears, and the students won't cop to blowing the dimm if they did make a mistake. Being under our warranty, the instructors don't really care how/why, either. So I'm unlikely to get something like "it happened when I did step 23", and we have to make some best guesses. -John O |
#9
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Burned DIMM pads
JohnO wrote: If it doesn't easily fit, there's a *reason* :-) Do the burned DIMMs also have bruised or filed-open notches? No, these are a *lots* of identical systems built to our specs, and students are using our instructions for removing and then reinstalling the dimm. Unfortunately, these systems don't have power supply switches, making the removal of the power cable necessary--and I suspect not always accomplished. We do tell the students to make sure the light on the mobo is off. Looks like we have to stick a meter on those pins and see what's there when off/AC-attached. Of all those computers (~1k) we've had maybe ten burned dimms, so there's nothing *completely* wrong with the instrux or hardware. Problem is, the instructors don't know exactly what step was being performed when the smoke appears, and the students won't cop to blowing the dimm if they did make a mistake. Being under our warranty, the instructors don't really care how/why, either. So I'm unlikely to get something like "it happened when I did step 23", and we have to make some best guesses. -John O I think you're looking over one of the things the man said he asked "Do the burned DIMMs also have bruised or filed-open notches?" I've found that (by my lousy counting) when a DIMM gets burnt by putting it in the wrong way, then ram contacts 85 and 77, - VDD and VDDQ respectively, get burnt on the RAM chip. There were certainly a distance of 8 between them - including one of them/'the first one' ..(85-77=8) smoke comes from the socket on the mbrd , whilst certain contacts on the ram get hit too. Those contacts on the RAM that get hit look burnt. perhaps, looking 'filed down'. They look different anyway. As if the metal has been filed fof and what was beneath the metal, the little area of that contact, is burnt. The RAM socket will also look more seriously messed up at the point of those ram contacts. Are you sure the sockets are burning and the ram modules are ok? by the way, you may get more answers from comp.sys.ibm.pc.hardware.chips |
#10
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Burned DIMM pads
I think you're looking over one of the things the man said
he asked "Do the burned DIMMs also have bruised or filed-open notches?" These dimms have a notch that's about 1/4-inch off center. Backwards, the notch is off by nearly a half inch. No way they go in backwards without flopping around in the socket. The one I'm looking at has no bruise in the right place. Anyone ever hear of "Blitz" memory? The sticker, chips, and board all have this name on them, and they don't exist on the web...we have a suspicion that they might just be crap modules. FWIW, our guys were playing this weekend and learned that a hot-swap works fine. :-) Are you sure the sockets are burning and the ram modules are ok? The dimms are obviously burned, pads at 184 and 181 are gone and the edge of the module shows heat/smoke damage...a scratch & sniff smells like burned pcb, too. Sockets show pins melted into the plastic. by the way, you may get more answers from comp.sys.ibm.pc.hardware.chips Thanks, if we need to pursue this further I'll check it out. -John O |
#11
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Burned DIMM pads
JohnO wrote: I think you're looking over one of the things the man said he asked "Do the burned DIMMs also have bruised or filed-open notches?" These dimms have a notch that's about 1/4-inch off center. Backwards, the notch is off by nearly a half inch. No way they go in backwards without flopping around in the socket. The one I'm looking at has no bruise in the right place. Anyone ever hear of "Blitz" memory? The sticker, chips, and board all have this name on them, and they don't exist on the web...we have a suspicion that they might just be crap modules. Maybe rebranded, if you put them in a windows machine, install everest or aida32, you might get the information stored within the ram chip. FWIW, our guys were playing this weekend and learned that a hot-swap works fine. :-) You mean you got away with it? No damage? Well, you can get away with a lot of really bad practices, a lot more than people generally think. Ps: is this hot swap as in powered off, but there's a little juice going through the circuits, or hot swap as in fully booted? There's a huge difference.... One is relatively safe, the other, well... |
#12
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Burned DIMM pads
FWIW, our guys were playing this weekend and learned that a hot-swap works fine. :-) You mean you got away with it? No damage? Well, you can get away with a lot of really bad practices, a lot more than people generally think. Ps: is this hot swap as in powered off, but there's a little juice going through the circuits, or hot swap as in fully booted? There's a huge difference.... One is relatively safe, the other, well... Power on, system running at the Win XP desktop, remove the dimm. Put it back in. Windows crashes, of course, but the hardware is fine. Amazing. For all we know the mobo or dimm could die in a month, but they are working fine right now. -John O |
#13
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Burned DIMM pads
How warm do they feel when the PC has been on and active for a while?
JS "JohnO" wrote in message ... FWIW, our guys were playing this weekend and learned that a hot-swap works fine. :-) You mean you got away with it? No damage? Well, you can get away with a lot of really bad practices, a lot more than people generally think. Ps: is this hot swap as in powered off, but there's a little juice going through the circuits, or hot swap as in fully booted? There's a huge difference.... One is relatively safe, the other, well... Power on, system running at the Win XP desktop, remove the dimm. Put it back in. Windows crashes, of course, but the hardware is fine. Amazing. For all we know the mobo or dimm could die in a month, but they are working fine right now. -John O |
#14
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Burned DIMM pads
"JS" @ wrote in message ... How warm do they feel when the PC has been on and active for a while? The guy who did it is putting out a major fire at the moment, I'll ask him later. If he has time, I'll have him measure it. -John O |
#15
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Burned DIMM pads
JS wrote: How warm do they feel when the PC has been on and active for a while? JS "JohnO" wrote in message ... FWIW, our guys were playing this weekend and learned that a hot-swap works fine. :-) You mean you got away with it? No damage? Well, you can get away with a lot of really bad practices, a lot more than people generally think. Ps: is this hot swap as in powered off, but there's a little juice going through the circuits, or hot swap as in fully booted? There's a huge difference.... One is relatively safe, the other, well... Power on, system running at the Win XP desktop, remove the dimm. Put it back in. Windows crashes, of course, but the hardware is fine. Amazing. For all we know the mobo or dimm could die in a month, but they are working fine right now. -John O Cool! |
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