Author: Jeremiah Penery
Date: 06:18:35 02/20/03
Go up one level in this thread
On February 19, 2003 at 11:40:27, Robert Hyatt wrote: >On February 19, 2003 at 00:52:09, enrico carrisco wrote: > >>If done properly and tested for reliability -- what reasons do you speak of? >>Most CPUs are purposely locked from higher than marked performance from the >>manufacturer for marketing and other reasons -- both Intel and AMD. This, in no >>way, means the CPU is incapable of such performance. > >The reason is _reliability_. As I explained in another post, circuits have a >distinct settling >time, which is what limits the clock frequency. Some circuits have varying >settling times >depending on the inputs. If you set the clock frequency too short, on occasion >the circuit >won't settle before the outputs are latched, and you get flakey results. Unless >you do a >complete and exhaustive test of all instructions, all inputs, you can't be sure >you haven't >stepped on this. I have debugged this problem in the past and don't _ever_ >intend to debug >it again. They don't make different circuits for different clock-speeds of the same chip. As long as cooling is sufficient, it's pretty safe to overclock a lower-speed processor to the same speed as the highest planned processor of the same core design. The manufacturers generally don't push their processors to the limit, so you can often go somewhat above that speed, even. 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).
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