[CentOS] Memory vs. Display Card

[Richard Karhuse]

On Sat, Mar 7, 2009 at 10:00 PM, Rick <ellis at spinics.net> wrote:
> Since memory has become quite cheap lately I decided to move from 2 GB
> to 6. When I installed the memory every thing was fine until I went to
> run level 5. At that point the screen turned to garbage and the system
> froze. Is there a way to fix this so I can use the memory I bought? Do
> I need a new display card?
>
> Current hardware:
>
>  Intel D975XBX2 Motherboard
>  VGA compatible controller: ATI Technologies Inc RV505 [Radeon X1550 64-bit]
>

First of all, lots and lots of data "missing" here .....

Secondly, I agree with other posters --> make sure that memtest86+ runs
successfully and finds all your memory.  Let it run *at least* overnight before
accepting the new memory.  [Note:  Three explicit things that you need to
check and report the results of here -- if you'd like more help.]

Third, check your BIOS settings -- particularly w.r.t. VGA memory, memory-hole
re-mapping, etc.  I'd do this before I'd run the memtests, btw.  Does the BIOS
see the memory?  Is the BIOS configured to map the VGA + PCI + ... (typically
up to 1 GB) memory to higher space?  Is your MTTR set to Discrete or
Continuous?  I'd run the Intel Linux Firmware BIOS test to see if the BIOS /
Memory are configured and compatible at this point.

Forth, what (precisely) CentOS kernel are you booting??  Does it support
greater than 4 GB of RAM??  Does it see all the memory -- both the 6 GB
of physical RAM plus the VGA + PCI re-mapped -- e.g., does it see almost
7 GB of memory??  How does the kernel see the memory (e.g., the MTTR
block -- which is one of the first things the system reports when it boots up)??

Fifth, after the GUI scrambles the screen, did you kill the session and/or
switch to an alternate Virtual Console and review both /var/log/messages
and X.org logfiles??

Once, you've got that, you might have a better idea of what's going on ...
(and maybe where your problem is ...)

HTH

   -rak-