Date: Fri, 17 Sep 1999 12:35:32 +0100 From: Michael Searle <searle@longacre.demon.co.uk> To: "Gary T. Corcoran" <garycor@home.com>, Randall Hopper <aa8vb@ipass.net> Cc: multimedia@FreeBSD.ORG Subject: Re: Is video overclocking risky? Message-ID: <19990917123532.07117@longacre.demon.co.uk> In-Reply-To: <37E1BDA1.2B806174@home.com>; from Gary T. Corcoran on Fri, Sep 17, 1999 at 12:03:45AM -0400 References: <19990916210053.A10590@ipass.net> <37E1BDA1.2B806174@home.com>
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On Fri, Sep 17, 1999 at 12:03:45AM -0400, Gary T. Corcoran wrote: > > Randall Hopper wrote: > > > > I have a new Matrox G200 PCI I picked up, and I notice I pick up about > > a 10% XStone increase by using "overclock_mem" in XFree86 3.9.16. > > > > So in practice, is this risky? Or do you just risk video corruption? > > > > > > From what little I know, I think this means it clocks the RAMDAC > > faster, so it (along with the memory) is being pushed. At high resolutions > > and refresh rates when the RAMDAC is already up toward the high end of its > > limits, I think this means it'll be running closer to or past the spec freq > > limit (maybe pulling more current than it was designed to). Is this > > right in practice? > > Whenever you clock chips beyond their specified limit, you risk overheating > them. While this may cause nothing but extra heat in the short term, in > the long term it can cause premature failure of your chips (video board) > [e.g. due to accelerated electro-migration of the "wires" in your chips]. > > I'm not familiar with exactly what "overclock_mem" means, but I suppose > it also may depend on your board manufacturer. For example, (at least > in the past) Diamond was famous for pushing their "normal" clock rates > up to the edge so they'd get better performance in the benchmarks. > I don't think I'd want to overclock my old Diamond video board because > of that... > > Gary > AFAIK, this is clocking the memory faster, not the RAMDAC. (The usual ways to overclock a video card are the memory and the accelerator.) I have a Matrox G200 AGP (SGRAM version) and under Windozo it can be clocked at over 120MHz (compared to 94.5MHz standard) for 3D and up to 130MHz for 2D only. Not all G200s can do this (most are clocked at 89MHz standard - an older version?), but it is a very overclockable chip. (I've not tried overclocking it in X, as I only have 3.3.5.) The G200 accelerator is locked to the memory speed, so this runs faster at higher clock rates also - the performance increase can be close to the clock increase. IMHO, long term effects are not very relevant to a video card. Chips are made to last several years but are obsolete in several months... If you are worried about heat though there are video card fans available, including one for the G200. -- searle@longacre.demon.co.uk To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-multimedia" in the body of the message
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