Date: Thu, 10 May 2007 17:23:17 +0100
From: Tom Evans <tevans.uk@googlemail.com>
To: Garrett Cooper <youshi10@u.washington.edu>
Cc: Robert Huff <roberthuff@rcn.com>, FreeBSD Mailing List <freebsd-questions@freebsd.org>
Subject: Re: WOW! {Or Holy whatever}
Message-ID: <1178814197.1231.48.camel@zoot.mintel.co.uk>
In-Reply-To: <46433EF8.2080805@u.washington.edu>
References: <20070509220908.GA50232@thought.org> <20070509230946.GA50585@thought.org> <F87B8C94-1473-4EB7-9DC2-6432D3F036E7@gmail.com> <20070510013453.GA52298@thought.org> <5CA2CC6B-72B6-46A1-9712-E258CFB4EB11@gmail.com> <4642A7F9.8070707@u.washington.edu> <17987.2963.612138.380335@jerusalem.litteratus.org> <46433EF8.2080805@u.washington.edu>
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--=-QdGdGIb84J2tkbi/1oZs Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Thu, 2007-05-10 at 08:49 -0700, Garrett Cooper wrote: > A good rule of thumb: Don't buy a video card with more RAM than 1/8 to=20 > 1/4 of the system RAM, because the RAM is shared with the system RAM,=20 > which means you have less overall system RAM to use for apps. >=20 > -Garrett Er? Whilst I agree with the sentiment (low end graphics cards with 512MB of RAM are solely there to rip off the unwary), that is complete tosh. Some cards dont have much/any onboard dedicated RAM; instead they use system memory. Examples of these are nvidia cards labelled 'TC' (Turbo Cache), most (all?) integrated intel video chipsets. The other issue is on i386. 32-bit systems have 4GB of address space to use. Since you want to be able to address the graphics cards memory, some of this address space is allocated so the OS can address the memory. This means that if system RAM + video RAM > 4 GB, some of the system RAM is unaddressable. That itself is a bit simplistic (its not 4 GB, its ~3.5 GB, for various reasons.) The main point is that if you have a system with 1 GB of system RAM and put in a graphics card with 640 MB of video RAM, you still have 1 GB of system RAM to play with, even though you have gone over 1/4 of the system RAM. Tom --=-QdGdGIb84J2tkbi/1oZs Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (FreeBSD) iD8DBQBGQ0bxlcRvFfyds/cRAp48AJwM0pqlKdcESY+8Jx12jUz/TLlNtQCdG4P+ EfyjgBLWwn4bx97iopJCfaE= =ZQuv -----END PGP SIGNATURE----- --=-QdGdGIb84J2tkbi/1oZs--
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