HP ProLiant ML350G5, ATI ES 1000, problem with Novell SLES 10 SP1

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hello NG,

i have a HP ProLiant ML350G5 running with SLES 10 SP1.
Kernel: 2.6.16.46-0.14-smp, 64 bit-SLES.

VGA-Adapter is a ATI ES 1000.
lspci says:
01:03.0 VGA compatible controller: ATI Technologies Inc ES1000 (rev 02) (prog-if 00 [VGA])
Subsystem: Hewlett-Packard Company Unknown device 31fb
Flags: bus master, stepping, medium devsel, latency 64, IRQ 7
Memory at f0000000 (32-bit, prefetchable) [size=128M]
I/O ports at 3000 [size=256]
Memory at f9ff0000 (32-bit, non-prefetchable) [size=64K]
[virtual] Expansion ROM at f9e00000 [disabled] [size=128K]
Capabilities: [50] Power Management version 2

In /var/log/messages i found regulary the following error:
Jun 26 11:00:36 pc53200 kernel: mtrr: type mismatch for f0000000,2000000 old: uncachable new: write-combining
The memory-adress is the one of the vga-controller.
The error appears mostly after booting, i think when the X-Server starts.
While googeling i found a lot of manipulating /proc/mtrr with echo. But i didn't suceed.
I tried:
echo "base=0xf0000000 size=0x08000000 type=write-combining" >| /proc/mtrr
but got the following error in the syslog:
kernel: mtrr: type mismatch for f0000000,8000000 old: uncachable new: write-combining.
What can i do ?
Thanks for any help.
Bernd