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Salvaging Defective DRAM
An anonymous reader writes "Ever wonder what happens to DRAM that fails quality assurance testing during manufacturing? Turns out a lot of it ends up as 'downgrade' memory and ends up in OEM memory modules. Last resort: use it in an answering machine, where the sampled audio can be very tolerant of bit errors."
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"Oh you left a message on the answering machine, naah I didn't get it must be the defective DRAM chips they use. Now you've managed to track me down using a detective agency I'll be sure to send you the cheque next week"
An Eye for an Eye will make the whole world blind - Gandhi
You just explained a lot about my fricking answering machine! I thought that no one ever called! And now I find out it is low grade ram? My god! I may really HAVE a social life!
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
No. I figured they forgot about it.
I knew there was a reason why I hated answering machines...now I actually have it! :)
...I forgot it. Musta been that defective OEM memory module I had implanted in my skull...
-RickTheWizKid
BadRAM patch.
Summary: This page proposes an approach to support RAMs with defective addresses, This may open interesting business perspectives, where those RAMs can be sold under a white label for less money rather than discarded of without any profit.
the url is:
http://rick.vanrein.org/linux/badram/
and I suddenly though, hmmm what happens to that defective DRAM, I open up Mozilla and what do I find an answer to my question.
This is the prime example of why I tell people I know not to buy ram off of the internet unless its from a major company that has good support. To many people buy 15-90 day warranty ram because its cheap, and when it fails they are upset that they have to replace it. If you pay a bit more money you get lifetime warranty ram... and why do you think they are willing to warranty it that long, because they know it works. people dont understand the testing process and think they are getting the same product buying cheap ram, as opposed to inexpensive ram...
Fire in the hands of the village idiot is no tool, but a weapon of mass destruction
Sheesh, evil *and* a jerk. -- Jade
I recall seeing an article awhile ago where companies were buying defective memory, and running them in these external testing units,which would identify which chip(s) on the stick were bad. I'm assuming they'd then unsolder the bad chip and recover one from another module. At that time some of those sticks had 8 chips on each side, so you could recover 15 good sticks from 16 bad ones. Considering the price of memory a few yrs ago, it was probably a worthwhile venture. Nowadays though, it's probably not worth anyone's time.
I work for the Department of Redundancy Department.
I've been waiting for the computer graveyard market to ramp up. Where does the rest of defective computer systems go?
This space intentionally left blank.
It sounds like yet another reason to stay away from compaq.
Disclaimer: On the other hand, I am kind of a psycho...
Audio quality on answering machines dont have to be that great. Because of the ability to resell defective DRAM overall costs of both answering machines and high quality DRAM has gone done.
Tech support is busy right now...please leave a message and we'll get back to you...
As long as there is a Second Amendment, there will always be a First Amendment.
if it didn't pass quality standards, then how else would they figure out which ones are defective?
-- Having a Creationist Museum is like having an Atheist place of worship
I sh*t you not.. they make great keyring fobs! just dont let your gf see it ;)
moo
There are some things in the article that are pretty out of date:
To reduce the test time, parallel chip testing usually is accomplished with eight to 16 chips in a row.
That's pretty low parallelism; there are memory testers out there that test over 200 devices at a time right now. And even the older, more common systems are probably testing 64 in parallel.
A special ink jet color marks the good dies.
This hasn't been true for years. Each device's pass/fail status is stored in a database, along with all other test results, and the whole process is automated enough that good die are binned out automatically. No need to physically mark the chip.
Due to the imperfection of the process, a percentage of the DRAM die contains some faulty cells.
That percentage is 100%. At modern memory sizes, you never get a perfect device without going through repair.
Well, have you ever wondered what happens to all the defected people that get produced?
They end up on earth.
I've been waiting for the computer graveyard market to ramp up. Where does the rest of defective computer systems go?
It's in my closet. All of it. The whole market. I'm waiting for the entire tech market to crash, so I can flood the market.
-- Having a Creationist Museum is like having an Atheist place of worship
Needless to say I find this very cool indeed, but I'm not sure I'd want to run it on my high availability, mission-critical web server for a bank ;-)
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"There are a lot of peeps complaining about substandard ram. If you had RTFA, you'd realize that the downgrade ram is reconfigured to skip the bad parts in the chips, so that it comes out as a normal module. Just because there is a faulty bit or 10 in a modules, doesn't mean the reast of that module is bound to fail. It could just have been an imperfection in the silicon or the circuit process.
:(
The downgrade ram has to pass further tests to insure the detours around the bad parts worked.
Granted, I probably wouldn't use this stuff in a mission critical server, but if you are buying for a mission critical server, you should be getting ECC registered with lifetime warranties anyway. Now for a small web or file server, or even a desktop, I'd use this.
Other people have mentioned memtest86. This program is your friend. Don't even bother with BIOS POST tests of RAM, just use this every once in a while if you REALLY want to find the problems. Too bad it won't run on my alpha server
-- Having a Creationist Museum is like having an Atheist place of worship
DRAM chips are usually have either 4, 8 or 16 bits per word. In order to construct a DIMM, 64 bits are needed. This means that with 4 bit DRAMs, you need 16 chips, with 8 bit DRAMs you need 8 vhips, and with 16 bit DRAMs you need 4 chips. usually you will see only the 4 or 8 bit DRAMs, because these occupy less board area for the same capacity. 16 bit DRAMs are only used for low capacity DIMMs.
When your DIMM supports ECC, it's 72 bits wide, which makes it more complicated. Usually its made of 18, 4-bit chips, or 9 8-bit chips.
(back in the 30 and 72 pin SIMM days, when memories were 8 or 32 bit wide, you could see ECC SIMMs that use 3 chip for 2x4+1=9 bits, or 2x16+4=36 bits).
If you see DIMMs with 12 chips, This is usually a cheap OEM SIMM using partially good DRAMs.
The Best way to identify such a DIMM, is to write down the marking on ALL the chips on it, and look them up in the internet. You then sum up all the DRAM bit widths, and see what you come up with:
If its 64 bits, its a normal DRAM.
If its 72 bits, its probably an ECC DIMM.
If its more, it's probably a DRAM using partially good DRAMs.
I wonder, does RAM faults develop over time, or are they introduced in manufacturing? That is, if you have some bad RAM, and correct it with Linux BadRAM, can you then be reasonably safe you won't get more faults?
Dead pixels on LCD screens are like this, if you don't have any dead pixels, you'll never get any. But how about RAM?
it was put onto eBay.
As a tip to Linux users with bad ram, try append="mem=fooM" where foo is an amount of ram below the broken area.
You can't judge a book by the way it wears its hair.
The Sinclair Spectrum used half working 32k memory chips for cost reasons. In the later models, the computer used the same system, even though by then they were using mostly working chips as the cost of memory had fallen.
You can get an extra 16k on most speccys by soldering a couple of links.
Eventually, I learned my lesson: If it ain't broke, don't fix it. My mechanical answering machine is now 18 years old and running fine. I have no plans of ever replacing it again.
If you happen to get hold of some defective DRAM then there is an excellent kernel patch called badram. This will allow you to mark off all faulty bits and use the ram with no performance lost. So provided you've got enough slots, you can have 4G (or 3.99G) at no cost!
when you can get help on /.!?
My server, and its cheapass ram, thank you.
You can't judge a book by the way it wears its hair.
Did anyone else read the title as "Salvaging DRM"? Hmmm, for minute there I thought answering machines were DRM protected.
Fight Crime - Shoot Back!
Seriously, I've had some of their OEM memory as part of a package deal, and it was very nasty stuff.
What's worse, before they would take it back, they wanted to "test" it, testing being limited to a couple runs of PC-Doctor, which is totally lightweight.
To make a long story short, they refused to take it back the first time, later it blew up my motherboard. They replaced the motherboard (it was part of the package) and sent me home, where I discovered my Athlon XP was also damaged. I took it up there, and they wanted to run PC-Doctor on it, but the "technician" (hah!) cracked the CPU while putting it in a "test board," so "oops, I guess we're replacing that."
P.S. One of the guys at the return desk who I got to know quite well told me, when I asked him why the "test boards" they were using always changed, that he thought they were boards that belonged to customers. Whether that meant boards in for repairs, or returned boards, I don't know or care - either is bad news.
P.P.S. This was at the Fry's in Wilsonville, Oregon. There is also an idiotic troll in the service department there who, after ignoring me waiting at an empty counter for 10 minutes while he chatted on the phone, wanted to charge me for a "missing" monitor stand on a monitor I was returning, refusing for 15 minutes to look in the bottom of the box under the styrofoam because monitor stands always come attached to the monitors, didn't you know? He finally looked when I demanded to talk to the manager, and of course it was there. I had a long discussion with the manager anyway over his, and their, incompetence (I reminded him of the memory fiasco) but the troll was still lurking there the last time I dropped by for consumables, which is all I will ever buy from Fry's, now. You can't miss him - he looks like he'd feel more at home in a raincoat, instead of his cheesy lab coat, roaming a playground on a sunny day.
Get off my launchpad!
You can be more specific than that. They end up in Congress.
i had a digital answering machine. funny thing with this was that the outgoing message recorded sound quality used to degrade over time! to this date, i have no idea how this could be the case. was it because of defective RAMs?
...no, I never really did wonder what happened to DRAM that failed the everpresent quality-assurance testing. Never really occured to me. So nyar.
Informatus Technologicus
This is why I stopped using answering machines and started using the voice messaging at the telco. Millions of little plastic boxes eating up electricity in millions of homes is bound to be less efficient than voice messaging at a central server.
The services at the telco let people leave messages when I am on the phone.
There is a very simple way to avoid dealing the morons who work at Fry's....
I call it http://www.crucial.com.
Micron RAM, cheaper than OEM, free shipping.
Seriously, with so many first-rate retailers on the net, there's *no* reason to do business with crapholes like Fry's.
You'll have better luck trying to install the keychain ram then you would OEM ram. =)
It's because they're THERE and most of the time, if you know what in the hell you're doing, you can get out of there in one piece. With the mail-order places, you have to wait a while. Sometimes that's just not an option. So you spend a little more than you would on the mail-order parts (like Crucial- which I'd reccomend to anyone that could afford the wait time) and get the premium parts from Fry's and go on.
I am not merely a "consumer" or a "taxpayer". I am a Citizen of the State of Texas
No Most major manufacturers use quality ram.
Compaq and IBM both use Kingston Memory. They also like to jack up prices for their "rebranded" Compaq/IBM ram which is just really a Kingston module with an even higher price.
Toshiba uses Samsung. I'm not sure about manufacturers like Dell or Gateway.
From a big-picture perspective, probably. However, voice mail is always(?) an added-value service for which the phone co. will charge on a monthly basis (at least that is my experience). From the vantage of the cheapskate user, it makes more fiscal sense to purchase a simple answering machine once than pay for voice mail service each and every month.
If it's that important to reach someone, people will call back.
You might be intrested to know that the routing problems which were plagueing the UK lately are still there in part. Don't blame slashdot for being down when its only your ISP's messed up... and now so this doesn't go 'off topic': Maybe their routers use some of the RAM? :b
*phew* hate it when I get modded down for going off-topic
Yah. Crucial was my main memory supplier for a while, and now that I've learned my lesson with Fry's, I'll go back to them.
I just won't take their word for how many sticks can fit in my motherboards, because they've been wrong twice for not counting the banks on the sticks they suggested.
I've tried Mushkin, but only because they were the best named sticks Fry's had when I was there, and the only 2-3-3 PC266s in stock. Mushkin's cool, but historically way overpriced. I wouldn't even have recognized the name except for the advertising on Anandtech.
Get off my launchpad!
why putting high quality ram (crucial, mushkin, etc) in an oem box (starts with a D, ends in ell) and the machine gripes about it.
/rolleyes
I can see it now: Error 13.2, good memory in a PoS OEM machine. Strike f1 to setup and f2 to continue.
Have you read the moderator guidelines? Well, have you, PUNK? (and I want a Karma: Gnarly option)
http://afrotechmods.com/stupid/memory/memory.htm
Granted, I probably wouldn't use this stuff in a mission critical server, but if you are buying for a mission critical server, you should be getting ECC registered with lifetime warranties anyway. Now for a small web or file server, or even a desktop, I'd use this.
I've always been a bit dubious as to the value of ECC memory, and whether it might not just be a bit of a sales tactic. Yes, I realize that it's theoretically possible for solid state storage to spontaneously fail. But it's also theoretically possible for any number of other things to break, and spontaneous RAM failure seems very, very low on the list of things to worry about.
I can't help but think that ECC memory is more useful from a marketing standpoint than a practical standpoint.
May we never see th
I wo~nder when we wil+ see tho&e defec%ive ch)ps in ou! deskt{p mach?nes?
In spite of what some other posters are saying, in the large HPUX server market, HP memory is much more reliable than Kingston memory, it's also much more expensive. Having said that I have seen more memory failures attributed to non-HP memory (not just Kingston) than anything. If your downtime is not worth more then go for less expensive memory. I have also seen a client try to install his own memory and detroy a system board in the proccess. No it was not covered under the HP warranty.
Semper ubi sub ubi
ellbee
You can't fight in here - this is the war room!
This is probably a good place to mention badram, the linux kernel patch that lets you use slightly defective memory modules.
You can use memtest to generate a list of bad areas in ram, and the badram patch reserves those blocks of memory on boot such that nobody can ever use them, effectively giving you a working stick of ram, only a little bit smaller than it is marked for.
If you're like me, you have a couple of cheapo sticks from who knows where that don't exactly work, and this patch is perfect for reviving those sticks.
--------
It's OK to be social, just don't tell anyone about it.
Turns out a lot of it ends up as 'downgrade' memory and ends up in OEM memory modules.
--
"Outlook not so good." That magic 8-ball knows everything! I'll ask about Exchange Server next.
Dell uses Micron and Infineon (Siemens) for SDRAM and DDR. For RDRAM I think they mainly use Toshiba. I always recommend Crucial to people because it is just the retail branch of Micron. Lifetime warranty and I've never had a failed stick.
I'm using a loaned Celeron 433 with an LX or EX chipset (no tool seems to be able to tell me, and I can't be bothered ripping the case off)
:(
I'm using 2x128mb SDR dimms (PC100 or 133 I beleive) running at only stock Celeron FSB speeds of 66mhz.
the ram is coming up as faulty all over the wazoo in memtestx86 and I'd love to know if MS has implimented a way of "reserving" dead ram spots so I can still use the PC reliably as it's a bit shaky? ? - is there a way at all, as I really don't want to replace even only 30$ worth of ram in a loaned box
Also - the dimms are single sided 8 chips per side (IIRC) and I was thinking maybe that setup isn't actually properly supported by the LX / EX chipset? - it's a CRAPPY hard to find jetway Celeron only board (quite a POS) - does anyone recall if there was an issue with double / single sided only ram back in the LX / EX days?
Thanks a tonne fellas
- Scott
Is there a way to get the badMEM program to be used on a boot disk. Reason I ask is, linux wont complete install on system (Red Hat 8), there is bad memory I would like to stop from being used so the install can complete.. Windows install crashes as well. Memtest shows bad areas. The memory is stuck on the MOBO, so I can't simply take it out. Any idea on how to get badmem loaded on a boot disk??
I actually bought two of those because it was so cheap. I let my system run continuously for 24hours with a RAM testing program that loads on boot. No errors detected. I figure if it passed that test I don't have anything to worry about and it was a good deal. Still, it's probably slower than my old PC133 RAM, but more ram is usually better than less, slower RAM due to disk caching.
I would still like to bye a gigabyte of name brand memory, but that would cost me well over $150 now.
check out memtest86. I have used it to check memory when doing troubleshooting on problem machines.
One option will generate the memory specs you can use with Linux to tell the kernel which memory spots to avoid. Although the idea of avoiding problem areas of known 'bad' memory sounds nice, I wouldn't use it in my machines.
Suncoast Linux - Sarasota, FL
Offtopic, but I have a board in my closet that used to be my main machine a while back. It had 3 32meg DIMM's in it. If I pulled any one of them, Win2k would blue screen. I couldn't take any ONE of them out and replace it, or it would blue screen on boot. Strangest thing.
-- Having a Creationist Museum is like having an Atheist place of worship
I work on Toshiba laptops, and whenever I look up a part number to add or replace RAM for Toshiba laptop it's almost always Kingston. I get all my part numbers off the Toshiba web site. Accessible only by authorized Toshiba Techs.
---- "Excuse me. Where's the children's gun section?"
I can recommend MemTest from HCI Design (free):
hcidesign.com/memtest
It find errors not found by Memtest86 (which runs outside windows). (These were real errors, I had problems with memory that Memtest86 doesn't found).
You had to let it run for some time though.
(My experience is with ver 1.0, it's now at 1.2.)
Mundus Vult Decipi
His name was Jim-- no, Joe. Anyway, his number is ... 635 ... 563 ... dammit.
555-653
Ben "You have your mind on computers, it seems."
Bad sticks happen to everyone at one time or another, it's just really rare with Crucial. The big thing that they excel at, however, is the excellent customer service. I bet you had a warranty replacement stick in your hands fairly quickly.
Murphy was an optimist.
Micron has a subsidiary that has been doing this for years.