Faulty Chips Might Just be 'Good Enough'

Ritalin16 writes "According to a Wired.com article, 'Consumer electronics could be a whole lot cheaper if chip manufacturers stopped throwing out all their defective chips, according to a researcher at the University of Southern California. Chip manufacturing is currently very wasteful. Between 20 percent and 50 percent of a manufacturer's total production is tossed or recycled because the chips contain minor imperfections. Defects in just one of the millions of tiny gates on a processor can doom the entire chip. But USC professor Melvin Breuer believes the imperfections are often too small for humans to even notice, especially when the chips are to be used in video and sound applications.' But just in case you do end up with a dead chip, here is a guide to making a CPU keychain."

Comments

Already being done...

[leshert]

If I remember correctly, digital answering machines use "reject" RAM chips that aren't suitable for data storage, because minor dropped bits in a recorded message aren't discernible.

Re:Already being done...

[Ed Avis]

If it's just RAM, and the defects are just the odd bad location here and there, then BadRAM could help. The main difficulty is getting the support loaded early enough, e.g. at installation time. DIMMs could have their own defect list and a way for the motherboard to query it.

Micron has done this for years with RAM

[Anonymous Coward]

Micron started a group over 15 years ago that tests RAM chips at all stages of production that fails testing.

When I worked there it was called the "Partials Division". This group invented the "audio ram" market. They have a wide ranging sorting and grading process. It is called "SpecTek" I believe now. I sometimes see low end memory modules with SpecTek Ram.
12 years ago, I was production technician in a Surface Mount Assembly division that shared a building with Partials. We used to assemble memory modules and even video cards that used "PC grade" chips from the partials group. Everyone said they were good enough, but personally I have always steered clear of them.
The last year I was at Micron, we had a lot of discussions with NEC, Intel and some Russian Fabs to provide the same services to them. We tested a couple million chips from these companies in tests. Never did hear what the end result was.

the FUTURE

[k4_pacific]

In the FUTURE, single core processors will be dual core processors where one side didn't pass quality control. Someone will eventually figure out how to hack the chip to use both halves anyways, and the market will be flooded with cheap dual core chips that don't always work. Remember, you read it here first.

Re:the FUTURE

[ltbarcly]

Probably. But only for one revision, then they'll stop it. This has been going on forever. The 486sx was identical to the dx early on, except the FPU was disabled. I have never heard of a hack to get around this. Video chips are the same story, a radeon 9500 IS a 9700, with half the pixel paths disabled usually due to defect. You can get around this in software even.

Here is where you can make out like a bandit. Buy up a bunch of the revision which is hackable. Then, hack the ones you can and sell them as such. Then wait until supplies run out, and sell the ones where the hack failed on ebay. People will be on the lookout for the hackable version, and will pay a premium to get it from you. Oh, don't mention that you already tried it and it didn't work. They get exactly what they paid for, so this isn't dishonest in the least.

Actually, this happened to me. I wanted the Radeon 9500 with the ram in an L configuration, because you can soft-upgrade it to a 9700 most of the time. I bought one on ebay since there were no more on newegg. I specifically asked the guy "L shaped ram" he says yes. I get it and everything seems fine. UNTIL I lift off the heatsink. There, instead of a thermal pad or tape, is silver thermal compound. Clearly he had lifted the heatsink, and then put it back on when the hack failed. At least he was nice enough not to leave the hosed heat-tape on there. I ended up with a good upgrade for about what the newer revision would have cost anyway.

Now, in the next revision they just update the manufacturing to make it impossible to do the hack, because it is a nightmare for them to support all the half busted products that have been 'fixed' (even if they just say no, receiving and testing those products for the hack, and even phone support, costs like a bastard), and it cuts into the sales of the top tier products, where they make the highest margin. For chip companies this is as easy as dinging the faulty side of the chip before they assemble it completely, or putting some sort of "fuse" on the silicon itself, which they then burn out if that side is faulty. There is no way to take apart a chip to work directly on the silicon, and if there is and someone actually does it it will be a "Prove you can" since the equipment will be in the millions. (I can imagine a physics grad student with access to the machinery if they are doing superconductor or quantum computing research)

Not a good idea

[IversenX]

There is a reason for throwing out those chips! Maybe it's true that _most_ human ears wont notice that the least significant bit has been flipped in a über-noisy phone recording for a digital answering machine, but what if it was the most significant? That would make an audible "pop".

Ok, so maybe for non-critical equipment in the "use-and-throwaway" category. But this will not bring us cheaper hardware, just less functional hardware. Those chips are _literally_ going nowhere slow.

If you've ever had to debug something that turned out to be flaky hardware, you KNOW it's a PITA. If anything, awareness should be increased when it comes to the really cheap brands. They aren't always very stable, but people sometimes go for the cheapest RAM anyway, and then complain to ME when it doesn't work. There actually is some connection between what you pay, and what you get. Argh.

I'm done rambling now, thanks for waiting..

OK until code is mixed with the data

[G4from128k]

Apart from some hard-wired devices (simple sound clip recorders) or downclocked low-end devices, I don't see how defective chips can be used. The article suggests that the occasional error is OK for audio and video, but how do you ensure that the faulty chip never has to handle code, memory pointers, configuration files, hashes, passwords, encrypted data, or compressed data. I suspect that modern-day audio and video datastreams are becoming more fragile as they carry more metadata, highly compressed data, DRM, software, etc.

Something tells me that the manufacturers that use semi-defective chips are going to lose all their savings on product returns, warranty costs, and technical support. Given the low cost of most consumer electronics chips and the high cost of service labor, I doubt they will want the hassles of unreliable products.

Not quite

[beldraen]

While I agree that analog processors probably hold some promise, there is one large issue with them: heat. A major reason why processors get hot in the first place is that after each cycle the state is returned to a neutral position, which usually means grounding the gates to discharge them. This waste energy has a large conversion over to heat. Analog processors can really be thought of digital with multiple states, instead of two. This means that while more work can be done, there is larger values of charge to disapate.

What has always had my curiousity for why it has not been seemly worked on is "reversable" chips. There are essentially two sets for every mechanism and the system toggles back and forth. The discharge of the old system is used to drive the new mechanism; thus, a lot of wasted discharge is conserved for reuse. Reversable chips are reported to generate far, far less heat. I have heard that Intel and others know about this, but it is simply a better immediate investment because consumers are happy paying for the current line of toasters.

i486 SX vs DX?

[Mac Mini Enthusiast]

Wasn't that the difference between the 486 SX and 486 DX, regarding the math coprocessor? Actually, I've heard two versions of the story. One is that the SX had the math coprocessor intentionally crippled by Intel, but sold for a cheaper price for larger volume sales.

The other version was that the coprocessor had the highest failure rating for the chip fabrication. So on these chips with a failed copressor, the coprocessor was turned off, but the rest of the chip was still usable.

I vaguely remember this whole practice was described in a computer book my friend was reading, because I remember a joke the author told about computer salesmen. Unfortunately I only remember the joke, not the useful info from that book. (This joke comes from the days of small computer shops)
Q : What's the difference between a computer salesman and a car salesman?
A : The car salesman knows when he's ripping you off.

Sinclair did this

[Spacejock]

Sir Clive Sinclair used defective RAM in the ZX Spectrum way back in 1982. They were chips with only one bank working, but the computers were wired to only use that one bank.

Old Computers Museum

quote: "To keep the prices down Sinclair used faulty 64K chips (internally 2 X 32K). All the chips in the 32K bank of RAM had to have the same half of the 64K chips working. A link was fitted on the pcb in order to choose the first half or the second half."

Remember, many of the best ideas have already been used.