Date: Mon, 26 Jul 1999 12:43:53 -0700 (PDT) From: "Eric J. Schwertfeger" <ejs@bfd.com> To: Cosmic 665 <the_hermit665@hotmail.com> Cc: freebsd-smp@FreeBSD.ORG Subject: Re: Overclocking Message-ID: <Pine.BSF.4.05.9907261205510.17960-100000@harlie.bfd.com> In-Reply-To: <19990726184848.36453.qmail@hotmail.com>
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On Mon, 26 Jul 1999, Cosmic 665 wrote: > It's awsome to hear all the stories about overclocking... but how stable is > overclocking "in reality"??? I'm not saying this to be a jerk or anything > but how much work could & should a CPU take at +50-75% it's clocked state > (especially a SMP system)?? How long could you run a CPU overclocked, or > if any of you guys are overclocking what's the longest a system has lasted > (in years or months)??? I got an ASUS P2B 5A and I was thinking about > (Maybe) overclocking the 333Mhz chip... but then again I can't risk buying > another MB or cpu if I screw up the computer :P I'm an overclocker from way back. The first overclocked CPU I ever dealt with was a 386DX-16 that ran at 25Mhz without a single glitch until long after a 386DX25 was useful for anything. Much of the practicality of overclocking comes from the family of chips. The same fabrication process is used for PPGA Celerons from 333mhz up to the latest 500mhz, so I wouldn't expect you to damage CPU or motherboard overclocking a PPGA 333 by 50%, as long as you didn't tweak the voltage in order to make it run. It may not work, but I don't think you'd damage anything. On the other hand, even the bottom-of-the-line PIII, at 450mhz, isn't going to overclock far, since the fastest in that family is currently 550mhz. The fact that 100mhz front-side-bus machines have nowhere to go that isn't overclocking the PCI bus on many motherboards probably doesn't help either. Oh, and I consider 50% to be the high end of usable overclocking, and even that depends on where you're starting from. I know that there are people that get more, but they don't do it with anything resembling normal CPU fans, have to hand-pick parts, etc. Overclocking is not something that I recommend to everyone. In fact, I refused to overclock anything that I sold (used to sell hardware) or consult on unless the customer specifically requested it and understood what it meant. Small amounts here and there might be a no-brainer, but it really does take time and effort to make higher amounts of overclocking stable. I'm guessing I'm going to be tweaking my machine for a week at least before I'm happy that I've gotten as much as I safely can out of it. I'm hoping to find a combination that is happy at 550mhz, but failing that 506mhz with a Memory clock of 92mhz and a PCI clock of 31mhz will keep me quite happy. (92 mhz is a magic number, as the PCI clock divider drops at 91mhz, and I don't want to run the PCI bus at 45.5mhz. Surprized ABIT doesn't let me set the PCI divider myself). As far as stability goes, I usually test my machines with a 24 hour "make world" loop. I've never had a CPU pass that test, and then flake out at a later date. The longest-overclocked CPU's I'm currently using are some PPro 150s that are completely happy at 180 over 3 years later, though they wouldn't make world at 200, even brand new. I've got friends using Pentium 166's at 266, K6-2 233's at 300, etc, that have all been in use at least a year. There are things to watch out for. UDMA drives quite often have a conniption if your PCI bus is clocked higher than 33.33mhz, and some PCI cards don't like that either. Another thing to watch is your AGP clock, if you're using an AGP video card. And one thing to keep in mind is that I'm saving less than $150 by spending all this time fussing with overclocking as compared to just buying 2 466 Celerons. I'm mostly doing this just for the sick twisted sense of having spent less than $400 for something that will be about twice as fast as anything we have at work. (Including Marketing's new PIII :-) For more advice, I'd suggest checking out some of the hardware sites, there are even a few dedicated to overclocking. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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