Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
In article <42891562$0$1163$5402220f@news.sunrise.ch>, Roland Scheidegger
<rscheidegger@gmx.ch> wrote:
> Paul wrote:
> > In article <pJRhe.15305$iU.12499@lakeread05>, "J&SB" <jandsb@cox.net> wrote:
> > It is unclear to me, whether with, say, WinXP, you would need to
> > add /PAE or /3GB to the boot.ini file or not. When "memory hoisting"
> > is involved, to lift the memory in the memory mapped I/O hole, above
> > the 4GB mark, then more than 32bit addressing is needed. One way of
> > getting this is with PAE. Some of this is explained in this posting.
> No matter what you do, Windows XP Home/Professional simply will not use
> ram which is mapped above 2^32, you can enable /PAE /3GB or whatever and
> it simply won't work. This is an artificial limitation of the PAE
> implementation in Windows XP. Windows Server 2003 Standard will support
> the full 4GB, for even more ram (with 4 unbuffered 2GB sticks composed
> of 16 128Mx8 chips this should be possible on that board, though these
> modules aren't quite mainstream yet...) you need even more expensive
> windows versions (enterprise, datacenter, up to 32/64GB)
>
> Alternatively, the Windows XP Professional x64 version supports the full
> 4GB too (in fact, up to 128GB) and should be a bit easier on your wallet...
> Alternative OS (no, DOS doesn't count...) usually support more than 4GB
> ram just fine too. That said, Asus is known to be sloppy with
> implementing features like memory remapping and sometimes doing it a bit
> wrong, so it might not work with all OS. Windows should be fine though
> (that's Asus standard answer with broken bios features "but it works
> with windows, so it obviously must be correct!" - even though Windows
> might complain too but just happens to ignore the error)
>
> Roland
I was looking for a Microsoft web page that would address the
issue of needing 5GB of address space, but only having 4GB of
physical memory. The KB articles that attempt to address memory
limits, aren't too precise about exactly what is supported.
This article mentions that WinXP will access above 2^32 when using
the PAE switch. Now, AMD64 has the MMIO feature, and I don't know
if that means the whole computer will work properly or not, with
this 5GB address space, 4GB physical configuration. A question
that has come up in my mind about this particular configuration,
is the layout of the kernel memory versus user space - if the kernel
lived in the upper GB of memory, perhaps PCI I/O operations would
never go near 2^32, further improving the odds that it might work.
http://blogs.msdn.com/carmencr/archive/2004/08/06/210093.aspx
Another disturbing thing in that thread, was the posting at the
bottom of the page. A user upgraded to SP2 and found the system
reported only 3.18GB when before SP2 it reports 4GB.
On the one hand, I could suggest to the OP that the best thing
would just be to try it and test it, but I'm not even confident
I could suggest a good test strategy that would exercise the
"corner cases" well enough to bless the resulting system. Maybe
simply installing the 4GB of memory, and enjoying the use of
3.1GB of it (the non PAE option), is as good as it'll get, without
a lot of unnecessary effort and expense.
One of the reasons I suggested going with the 4GB config, is based
on a few experiences people have had mixing pairs of DIMMs on
these boards. There was one person, who mixed a pair of CAS2
256MB DIMMs with a pair of CAS3 DIMMs, and one pair of DIMMs was
ignored by the BIOS. That is now making me nervous about recommending
mixed sets of DIMMs to people, like 2x1GB + 2x512MB. If would be
pretty embarrassing to suggest such a config, and get a posting
later lamenting the fact that the new DIMMs were ignored. So,
whether the OP goes with a 3GB configuration or a 4GB configuration,
both of those configurations will require finding working
examples in the private forums somewhere.
Paul
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