allocate more videoRam in xorg

edit

Hello guys,

i have a dell inspiron 1545 laptop, core2duo, 4gb of ram, and intel 4500MHD (G45 CHIP) gpu this gpu have a 64mb dedicated memory + the shared memory with the ram, in windows the shared memory its 1631+64 dedicated its a totaly of 1695mb i see it in dxdiag and attach picture about it

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but in fedora its only have 256mb, so im triying to get more vram for the gpu changing it in the xorg.conf and also change the accelmethod to sna in the devices section:

Section "Device"
    Identifier  "Card0"
    Driver      "intel"
    BusID       "PCI:0:2:0"
    Option      "AccelMethod"  "sna"
    VideoRam 1735680
EndSection

but they no work, the 256mb of memory for the gpu persist after restart i check in terminal and not work

bash-4.2$ lspci -v -s 00:02.0
00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07) (prog-if 00 [VGA controller])
        Subsystem: Dell Device 02aa
        Flags: bus master, fast devsel, latency 0, IRQ 45
        Memory at f6c00000 (64-bit, non-prefetchable) [size=4M]
        Memory at e0000000 (64-bit, prefetchable) [size=256M]
        I/O ports at efe8 [size=8]
        Expansion ROM at <unassigned> [disabled]
        Capabilities: <access denied>
        Kernel driver in use: i915

bash-4.2$

im using this guide for create the xorg.conf https://fedoraproject.org/wiki/Howtocreate_xorg.conf and also try create a etc/X11/xorg.conf.d/20-intel.conf

how i can get it working and chang the videoram and accelmethod in fedora 17 x64 KDE Spin

thanks to all