Author: Matt Taylor
Date: 11:46:31 02/20/03
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On February 20, 2003 at 11:50:31, Robert Hyatt wrote: >On February 20, 2003 at 09:18:35, Jeremiah Penery wrote: > <snip> >>It's not all that difficult to 'debug' any problems with overclocking. Run a >>program like Prime95 for a while (catches errors MUCH faster than anything else >>I've seen). If you get errors, clock down and see if they go away. Obviously, >>errors are a sign of an unsafe overclock. It certainly doesn't mean that EVERY >>overclock is unsafe. Otherwise, you'd better send back those 2.8GHz Xeons right >>away, because they're nothing more than overclocked 2.5GHz ones (in a manner of >>speaking). > >The problem is that the 'error signs' are not like red flags. It isn't easy to >detect a single bit >error in a floating point multiply, for example, if it only happens once every >10^6 multiplies >with specific bit patterns. And that kind of failure has happened _many_ >times... Yes. In two different cases I had bad ram (and did not realize it) because signs were vague and intermittant. Though ram is not the same as a CPU, I think these two examples clearly demonstrate how errors can go undetected. The ram was running at rated speed, I think. I'm not sure because my motherboard's default memory timings were too aggressive, and I had to go into the BIOS to change the CAS latency. (There may have been other timings that were too aggressive as well.) In the first case, I ran several months with only a few warnings. The only indicator I had was the java compiler crashing NT. After that, I didn't have any problems for another month or two. All of a sudden the system became horribly unstable. I removed the good DIMM and the other failed POST. In the second case, I did not experience instability at all for several months. I was on a coding spree at 4 AM. I recompiled my program, and the compiler bombed out with an error. There were invalid characters in some runtime header file. I thought that was strange, but I replaced the header file with a copy from another machine and kept on working. About 30 minutes later, the compiler started crashing. I replaced the compiler's executable and things went smoothly again. The next day I put together my dual-CPU system and used the same ram, and everything ran fine. I concluded that it must have been a motherboard or CPU problem (the dual wasn't crashing or doing anything weird). About a month later I ran the AMI diagnostics program, and it turned out it really was the ram. After replacing the ram, I've used that same system for months as a router at home. In a twist of irony, I loaned it recently to a friend whose 1.8 GHz Pentium 4 broke. (Or so we thought.) -Matt
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