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Questions about DDR RAM
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Questions about DDR RAM
On Wed, 03 Oct 2007 16:30:41 -0000, Andrew
put finger to keyboard and composed: On 3 Oct, 08:55, Igor wrote: However, I plan on putting together a PC from scratch in the near future, so perhaps ECC support is something I should be looking for in a motherboard. In a nutshell, why is ECC capable memory more desirable? It has additional bits used to store checksum information so that errors can be detected and simple ones corrected. In short, it's a reliability thing. Without knowing much about your set up, it's impossible to be sure but at three or four times the cost of normal RAM I doubt it will be a cost-effective way of improving reliability. ECC just adds one extra RAM, ie 9 chips versus 8, or 72 bits versus 64. Even allowing for economies of scale, I can't see why you would expect a 3x or 4x price difference. Kingston 1GB 333MHz DDR ECC Registered CL2.5 DIMM Dual Rank, x8 (US$70): http://www.ec.kingston.com/ecom/conf...R333D8R2 5/1G Kingston 1GB 333MHz DDR Non-ECC CL2.5 DIMM (US$54): http://www.ec.kingston.com/ecom/conf...333X64C 25/1G If you want to do that on most systems, you're better off spending the money on things like fitting a UPS and RAID storage - these cover much less reliable elements of the system. Memory is fairly reliable provided you aren't recklessly overclocking things so I'd consider ECC inappropriate on all but the most mission- critical systems. Unless you are talking about a machine already fitted out with a UPS, hot-swappable RAID, redundant power supplies and preferably an secure, climate controlled machine room to put it all in there are more important risk factors to consider. - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |
#43
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Questions about DDR RAM
"kony" wrote in message ... On Fri, 5 Oct 2007 15:17:57 +0000 (UTC), Andrew Smallshaw wrote: Yes, it did save money but why did the computer industry en masse decide that it could safely be dispensed with? Because they don't particularly care if a customer's calculations/etc end up wrong if it's not guaranteed for some critical use. The industry didn't actually abandon it for critical uses. In fact, for critical usage some companies have gone far beyond normal SEC/DED error correction in servers. I suppose I ought to trim the crossposting... |
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Questions about DDR RAM
On Sun, 7 Oct 2007 21:54:21 -0500, "Del Cecchi"
wrote: "kony" wrote in message .. . On Fri, 5 Oct 2007 15:17:57 +0000 (UTC), Andrew Smallshaw wrote: Yes, it did save money but why did the computer industry en masse decide that it could safely be dispensed with? Because they don't particularly care if a customer's calculations/etc end up wrong if it's not guaranteed for some critical use. The industry didn't actually abandon it for critical uses. In fact, for critical usage some companies have gone far beyond normal SEC/DED error correction in servers. If you are referring to ECC schemes and not memory mirroring, I'd be interested in examples that *don't* simply use n Hamming codewords to turn n-bit-wide full chip failures into correctable events - which really wasn't that remarkable, revolutionary or heroic when it was first employed - about 20 years ago... I suppose I ought to trim the crossposting... And what fun would that be? /daytripper ;-) |
#45
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Questions about DDR RAM
In alt.comp.hardware.pc-homebuilt daytripper
wrote: On Sun, 7 Oct 2007 21:54:21 -0500, "Del Cecchi" wrote: "kony" wrote in message . .. On Fri, 5 Oct 2007 15:17:57 +0000 (UTC), Andrew Smallshaw wrote: Yes, it did save money but why did the computer industry en masse decide that it could safely be dispensed with? Because they don't particularly care if a customer's calculations/etc end up wrong if it's not guaranteed for some critical use. The industry didn't actually abandon it for critical uses. In fact, for critical usage some companies have gone far beyond normal SEC/DED error correction in servers. If you are referring to ECC schemes and not memory mirroring, I'd be interested in examples that *don't* simply use n Hamming codewords to turn n-bit-wide full chip failures into correctable events - which really wasn't that remarkable, revolutionary or heroic when it was first employed - about 20 years ago... It's just a hamming-code. However, about 99% of memory installed on PCs is *not* EEC or even parity enabled. They all *should* be. I suppose I ought to trim the crossposting... And what fun would that be? /daytripper ;-) -- _____ / ' / â„¢ ,-/-, __ __. ____ /_ (_/ / (_(_/|_/ / _/ _ |
#46
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Questions about DDR RAM
"daytripper" wrote in message ... On Sun, 7 Oct 2007 21:54:21 -0500, "Del Cecchi" wrote: "kony" wrote in message . .. On Fri, 5 Oct 2007 15:17:57 +0000 (UTC), Andrew Smallshaw wrote: Yes, it did save money but why did the computer industry en masse decide that it could safely be dispensed with? Because they don't particularly care if a customer's calculations/etc end up wrong if it's not guaranteed for some critical use. The industry didn't actually abandon it for critical uses. In fact, for critical usage some companies have gone far beyond normal SEC/DED error correction in servers. If you are referring to ECC schemes and not memory mirroring, I'd be interested in examples that *don't* simply use n Hamming codewords to turn n-bit-wide full chip failures into correctable events - which really wasn't that remarkable, revolutionary or heroic when it was first employed - about 20 years ago... I suppose I ought to trim the crossposting... And what fun would that be? /daytripper ;-) In some sense it is a hamming code or along those lines. but it includes redundant bit steering, correction of double errors when one is hard and the other soft, package codes, scrubbing, etc. The whole quote was "far beyond normal SEC/DED...." eg 64/72 type codes that do single bit correction and double bit detection. del |
#47
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Questions about DDR RAM
In comp.sys.ibm.pc.hardware.chips Frank McCoy wrote in part:
However, about 99% of memory installed on PCs is *not* EEC or even parity enabled. They all *should* be. Oh, pray tell, why? Do you believe you know the PC business better than Intel, AMD, Dell, HP, ... who have decided to manufacture chipsets and computers without ECC? Do you believe ~50 US$/box is better spent on ECC than on improved capacitors, mobo layers, cabling, cooling or shielding? There are always many improvements possible. The key is to choose the best ones. Not fixate like a kid in a candy store. -- Robert |
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Questions about DDR RAM
In alt.comp.hardware.pc-homebuilt Robert Redelmeier
wrote: In comp.sys.ibm.pc.hardware.chips Frank McCoy wrote in part: However, about 99% of memory installed on PCs is *not* EEC or even parity enabled. They all *should* be. Oh, pray tell, why? Do you believe you know the PC business better than Intel, AMD, Dell, HP, ... who have decided to manufacture chipsets and computers without ECC? Do you believe ~50 US$/box is better spent on ECC than on improved capacitors, mobo layers, cabling, cooling or shielding? It shouldn't add more than 10% to the price of memory; which would be about 2% or less of the price of the computer itself. The problem isn't Intel or anybody else with the possible exception of IBM; but there only slightly. The problem is custom and history. They didn't do it in the past, for fairly good and decent reasons. They don't do it *now* because they didn't do it in the past. That is NOT a good reason. There are always many improvements possible. The key is to choose the best ones. Not fixate like a kid in a candy store. The problem is: WITH ECC built in, probably over half the cases of "Blue Screen of Death" or computer crashes and foulups *could* be things of the past! Even in cases where things like poor capacitors cause spikes, having ECC memory in the machine would obviate a large portion of those problems. The original reasons of the extra logic and extra expense just ARE NOT that relevant any more. They shouldn't even SELL non-ECC memory, for the relatively tiny price-differential versus the HUGE difference in reliability. It's like selling retread tires as new ones for almost the same price. Sure they're CHEAPER ... marginally. The worst part is, people could actually be KILLED by such mistakes made by a computer that might have been corrected with ECC ... Yet nobody will trace it back to that; just: "Sorry, the computer crashed!" That's unlike a bad tire, which eventually *will* get noticed after enough people die. Worse-yet, people aren't even being educated as to what the difference is. Essentially they're told and even believe that non-ECC memory is just as good, only cheaper. "I've ran my computer for years without ECC; and it ran just FINE!" Only that ignores the freezups, crashes, blue-screens, and other crap that got attributed to software instead of memory failures. ;-{ These days people seem to *expect* such failures, when 99.99% of the ones caused by bad memory (probably well over half) could be fixed. Most people ass-u-me that their memory is good; never EVER running a memory-test other than the completely useless crap on boot. Hell, most people, if a computer is crapping out, just replace the whole thing. In fact, many computer-repair places *encourage* their customers to do just that ... It makes more money for the company; while running a good memory-test takes up very valuable technician time and space in the repair-shop. For a mere pittance in extra cost these days, especially if ECC memory was the *standard* instead of the rarely-used, the "extra cost" would be a huge monetary *gain* instead of a loss. Most especially so in customer satisfaction. Still, they don't count "customer satisfaction" as worth a dime these days, not in comparison to saving ten or twenty cents on a part, do they? -- _____ / ' / â„¢ ,-/-, __ __. ____ /_ (_/ / (_(_/|_/ / _/ _ |
#49
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Questions about DDR RAM
On Mon, 08 Oct 2007 18:48:57 GMT, Robert Redelmeier
wrote: In comp.sys.ibm.pc.hardware.chips Frank McCoy wrote in part: However, about 99% of memory installed on PCs is *not* EEC or even parity enabled. They all *should* be. Oh, pray tell, why? Do you believe you know the PC business better than Intel, AMD, Dell, HP, ... who have decided to manufacture chipsets and computers without ECC? They sell ECC equipped systems too. Would you believe you knew better if you chose standardized parts instead of proprietary motherboards, cases and PSU? Most agree on that. The idea of blindly following an OEM is contrary to our goals. |
#50
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Questions about DDR RAM
Frank McCoy wrote:
In alt.comp.hardware.pc-homebuilt Robert Redelmeier wrote: In comp.sys.ibm.pc.hardware.chips Frank McCoy wrote in part: However, about 99% of memory installed on PCs is *not* EEC or even parity enabled. They all *should* be. Do you believe you know the PC business better than Intel, AMD, Dell, HP, ... who have decided to manufacture chipsets and computers without ECC? That's a very good question. There are always many improvements possible. The key is to choose the best ones. Not fixate like a kid in a candy store. Maybe it's one of his brands (like lots of quotation marks and asterisks). The problem is: WITH ECC built in, probably over half the cases of "Blue Screen of Death" or computer crashes and foulups *could* be things of the past! With Windows XP, almost all BSODs are a thing of the past. After years of using Windows XP, I can say "hooray, the stupid operating system knows how to shut down a program without forcing me to reboot". I thought the same thing after buying Windows 98 and after buying Windows ME, but months of use proved that idea to be wishful thinking. Even in cases where things like poor capacitors cause spikes, having ECC memory in the machine would obviate a large portion of those problems. I cannot recall seeing data corruption caused by hardware. Considering the fact that I have frequently copied entire Windows partitions for about a decade, you might think something that memory could cause a problem with would go wrong, but it doesn't. Making sure that the electricity flowing into your computer and out of your power supply is in good condition can go a long way to preventing serious malfunction. For a mere pittance in extra cost these days, especially if ECC memory was the *standard* instead of the rarely-used, the "extra cost" would be a huge monetary *gain* instead of a loss. Most especially so in customer satisfaction. In that imaginary situation where you are selling PCs, you are asking people to pay for something they don't need. |
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