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Can a Pentium-4 CPU partially fail? (internal cache performancedegradation)
I have several idential Soyo i845 motherboards that date from 2003 -
2005 time-frame, and several 2.53 ghz Pentium-4 CPU's (.13 micron single core) with 8k/512k cache. All boards have had various electrolytic capacitors replaced within the past year. One board in particular has been problematic over the past few months despite replacing most of it's capacitors. The system (running Windoze) performs spontaneous reboots and even though a mem-test might take over 50 passes after 6 hours of testing, it will show memory errors at some point. But the memtest shows something interesting. When run on two similar board-CPU systems, memtest says this: L1 cache - 8kb - 20763 mb/sec L2 cache - 512kb - 17714 mb/sec Memory - 512mb - 1052 mb/sec But on the problem system, I get this: L1 cache - 8kb - 87xx mb/sec L2 cache - 512kb - 65xx mb/sec Memory - 512mb - 559 mb/sec I used "xx" because I didn't write it down. But clearly there is something strange about those numbers. Bios settings were the same for all boards, ram setting set to SPD. I pulled what now could be a problem CPU and tried it in one of the other motherboards (a board that has a 2.6 ghz celeron) and got the same low score for cache/ram speed. I replaced the now likely questionable CPU on what I thought was a problem board with the next best available one that I had on-hand (3.2 ghz Celeron-D) and got these scores: L1 cache - 16kb - 22376 mb/sec L2 cache - 256kb - 19630 mb/sec Memory - 512mb - 1033 mb/sec So the board and memory can indeed perform similarly to the other problem-free boards, but I now seem to have a P4 CPU that has internal issues with regard to cache and memory speed (the only parameters I'm easily able to test). This CPU is SL6EG. Anyone know how a CPU could partially fail along these lines? |
#2
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Can a Pentium-4 CPU partially fail? (internal cache performancedegradation)
Intel Guy wrote:
I have several idential Soyo i845 motherboards that date from 2003 - 2005 time-frame, and several 2.53 ghz Pentium-4 CPU's (.13 micron single core) with 8k/512k cache. All boards have had various electrolytic capacitors replaced within the past year. One board in particular has been problematic over the past few months despite replacing most of it's capacitors. The system (running Windoze) performs spontaneous reboots and even though a mem-test might take over 50 passes after 6 hours of testing, it will show memory errors at some point. But the memtest shows something interesting. When run on two similar board-CPU systems, memtest says this: L1 cache - 8kb - 20763 mb/sec L2 cache - 512kb - 17714 mb/sec Memory - 512mb - 1052 mb/sec But on the problem system, I get this: L1 cache - 8kb - 87xx mb/sec L2 cache - 512kb - 65xx mb/sec Memory - 512mb - 559 mb/sec I used "xx" because I didn't write it down. But clearly there is something strange about those numbers. Bios settings were the same for all boards, ram setting set to SPD. I pulled what now could be a problem CPU and tried it in one of the other motherboards (a board that has a 2.6 ghz celeron) and got the same low score for cache/ram speed. I replaced the now likely questionable CPU on what I thought was a problem board with the next best available one that I had on-hand (3.2 ghz Celeron-D) and got these scores: L1 cache - 16kb - 22376 mb/sec L2 cache - 256kb - 19630 mb/sec Memory - 512mb - 1033 mb/sec So the board and memory can indeed perform similarly to the other problem-free boards, but I now seem to have a P4 CPU that has internal issues with regard to cache and memory speed (the only parameters I'm easily able to test). This CPU is SL6EG. Anyone know how a CPU could partially fail along these lines? You haven't told us if these CPUs have hyperthreading, and if so if it's enabled. I have never tested telling a BIOS to enable HT if the CPU didn't support it, but it comes to mind as one of the things which used to differentiate between systems I used when the P4 was current tech. I suspect the CPU is in some way defective (might even be one of the ones with the F00F bug Intel replaced for free), but I do remember HT being an issue, and at least with Linux a feature which was good for about 30% better performance for some real work. |
#3
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Can a Pentium-4 CPU partially fail? (internal cache performancedegradation)
Bill Davidsen wrote:
But the memtest shows something interesting. Instead of getting this: L1 cache - 8kb - 20763 mb/sec L2 cache - 512kb - 17714 mb/sec Memory - 512mb - 1052 mb/sec I get this: L1 cache - 8kb - 87xx mb/sec L2 cache - 512kb - 65xx mb/sec Memory - 512mb - 559 mb/sec This CPU is SL6EG. You haven't told us if these CPUs have hyperthreading, The SL6EG does not have hyperthreading: http://www.cpu-world.com/sspec/SL/SL6EG.html The only .13 micron (Northwood) CPU's to have hyperthreading were the ones that ran at 3.08 ghz. I see this from the wiki article on Pentiums: -------- Overclocking early stepping Northwood cores yielded a startling phenomenon. While core voltage approaching 1.7 V and above would often allow substantial additional gains in overclocking headroom, the processor would slowly (over several months or even weeks) become more unstable over time with a degradation in maximum stable clock speed before dying and becoming totally unusable. This became known as Sudden Northwood Death Syndrome (SNDS), which is caused by electromigration.[11] -------- |
#4
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Can a Pentium-4 CPU partially fail? (internal cache performancedegradation)
Intel Guy wrote:
Bill Davidsen wrote: But the memtest shows something interesting. Instead of getting this: L1 cache - 8kb - 20763 mb/sec L2 cache - 512kb - 17714 mb/sec Memory - 512mb - 1052 mb/sec I get this: L1 cache - 8kb - 87xx mb/sec L2 cache - 512kb - 65xx mb/sec Memory - 512mb - 559 mb/sec This CPU is SL6EG. You haven't told us if these CPUs have hyperthreading, The SL6EG does not have hyperthreading: http://www.cpu-world.com/sspec/SL/SL6EG.html The only .13 micron (Northwood) CPU's to have hyperthreading were the ones that ran at 3.08 ghz. I see this from the wiki article on Pentiums: -------- Overclocking early stepping Northwood cores yielded a startling phenomenon. While core voltage approaching 1.7 V and above would often allow substantial additional gains in overclocking headroom, the processor would slowly (over several months or even weeks) become more unstable over time with a degradation in maximum stable clock speed before dying and becoming totally unusable. This became known as Sudden Northwood Death Syndrome (SNDS), which is caused by electromigration.[11] -------- I hesitate to blame you errant cpu on this, unless you were OCing the hell out of it. However, I have another (also unlikely) thought, does some part of your boot process involve loading firmware updates? Might the bad cpu have errata? I admit, I have but a single P4 left in use, it was my wife's, and I am leaving it as she liked it, having no particular reason to do otherwise. |
#5
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Can a Pentium-4 CPU partially fail? (internal cache performance degradation)
On Mar 25, 9:30*am, Intel Guy wrote:
I see this from the wiki article on Pentiums: -------- Overclocking early stepping Northwood cores yielded a startling phenomenon. While core voltage approaching 1.7 V and above would often allow substantial additional gains in overclocking headroom, the processor would slowly (over several months or even weeks) become more unstable over time with a degradation in maximum stable clock speed before dying and becoming totally unusable. This became known as Sudden Northwood Death Syndrome (SNDS), which is caused by electromigration.[11] -------- I think sustained overclocking is about the only thing that kills CPUs. I have stripped lots of discarded PCs, and the CPU is often the only good component in them. Even when they were left out in the rain, or somebody dented the hard drive with an Estwing geologists pickhammer, and had a few swings at the mainboard for good measure. |
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