This is part of The Pile, a partial archive of some open source mailing lists and newsgroups.
Subject: [OFF-TOPIC]Re: overclocking cpu's (long) From: "Sean Conway" <seanconway@home.com> Date: Fri, 12 Mar 1999 18:56:47 -0500 >This really seams a bit off topic. Could you perhaps try one of the >hardware groups? Uh, can you avoid sending messages back to the ENTIRE LIST when you are nitpicking? (if you must nit-pick, just reply to the sender). And to answer the original question (re: overclocking) Overclocking has a lot of good benefits, and if done carefully, only a few minor benefits. A chip determines its frequency (read: speed) by taking is FSB speed (Front Side Bus), and multiplying it by a specific multiplier. These settings can be manipulated through jumpers, DIP switches, or through the BIOS (in some boards). The only difference, for example, between a Pentium II-400, and a Pentium II-450, is that the p2-400 is set at 4 * 100 = 400 MHz, and the p2-450 is set at 4.5 * 100 = 450 mhz. Note, however, that most modern CPUs are multiplier locked. This means that the multiplier that they use cannot change. This still allows you to overclock the FSB, however. You will never be allowed to select just any FSB, you will have to choose from a range given to you by your respective motherboard. Here are some common FSB settings, although boards designed for overclocking, such as Abit BX6 often have more settings): 60 66 75 83 100 103 112 124 (not that common) 133 So in the case of the p2-400, we could change the FSB to be: 4 * 112 = 448 mhz, which would actually give us better performance than a p2-450, for less money. (the reason the performance would probably be better is that the FSB effects more system speeds than just the CPU frequency - overclocking the FSB will have a small effect on RAM, your PCI peripherals, your AGP graphics card, and in some cases your cache. This should be enough to make it slightly faster than the p2-450, even though it has a slightly slower clock speed). There are some downsides. The higher you overclock, the more heat the CPU produces. If the CPU becomes too hot, it will stop working, or become unstable. This can be solved by getting extra fans - high quality overclocking specific fans are available, for a price, from http://www.computernerd.com and other sites. Another problem is that your CPU may be cool enough, but the FSB changes may make other parts of your system unstable (including your RAM, cache, graphics card, and in _extreme_ cases other peripherals). For example, when you change the FSB from 100 -> 133, your are changing: the RAM speed from 100 -> 133 (since the RAM speed is the same as the FSB speed) the cache (the exact change will depend on the system) the PCI bus, from 33 -> ~44, since the PCI bus speed is defined (by default) as 1/3 the FSB, giving the PCI bus its default frequency of 33 MHz In some motherboards, this can be solved by changing the divider that the PCI bus uses to get its frequency (generally, from 1/3 to 1/4) the AGP bus, from 66 -> ~89, since the AGP bus gets its speed by dividing the FSB by 2/3. this is often a serious limitation to overclocking, since this cannot be changed, regardless of motherboard. this can be partially solved by getting high quality RAM (try CAS-2 RAM, PC-133 certified RAM, or RAM by Goldstar, Samsung, and other reputable companies). Another problem with overclocking is that it will "burn" out the CPU faster than normal. This is due to a process called electro migration, which occurs normally in CPUs, but is accelerated in overclocked systems. Personally, this is not an issue, since CPUs should only "burn" themselves out after 10-15 years, so shortening this by a few years should not be significant to most (home) users. Overclocking is not very appropriate many parts of the commercial market, as it may void the warranty on the CPU, and may also cause instability, no matter how many fans you use. I think that overclocking is a very good practice for most competent home users, but is not appropriate for the corporate market (where you get a larger budget, anyway). some URLs to check out: www.sharkyextreme.com www.tomshardware.com www.bxboards.com Hope this is useful. Sean Conway