Bonjour je viens de changer la ram de mon pc, je suis passé de 2go a 4go mais ubuntu ne détecte que 3go est-ce normal.
Merci
A oui a savoir que wind… avec vist… lui détecte bien les 4go
C’est une limitation du 32bits, il n’y a pas d’autre solution que de passer à un système 64bits :).
Ok merci, mais depuis que j’ai changer la ram j’ai juste un petit souci ubuntu démarre beaucoup plus lentement.
Il fallait ajouter des barrettes, pas en enlever 
Plus sérieusement, boot sur un memcheck (“Memory test”) et regarde les résultats.
ok merci je fait le test.
Avant de passer à de long test comme memtest, il faut d’avoir regarder ce que voit linux :
lshw -C memorySi les 4G sont bien reportés, alors il te faudra recompiler le kernel avec l’option CONFIG_HIGHMEM4G ou installer un noyau bigmem si ta distribution en propose.
Donc voila le resultat:
*-memory
description: System memory
physical id: 0
size: 3033MiB
CONFIG_HIGHMEM3G
bash: CONFIG_HIGHMEM3G : commande introuvable
Peu-têtre tout simplement que ta carte mère ne supporte pas plus de 3 go. Avec la commande sudo lshw
tu auras ce renseignement:
CONFIG_HIGHMEM4G n’est pas une commande mais un paramètre de configuration pour la compilation du noyau.
voila le résultat:
[code] description: PCI bridge
product: Mobile PM965/GM965/GL960 PCI Express Root Port
vendor: Intel Corporation
physical id: 1
bus info: pci@0000:00:01.0
version: 03
width: 32 bits
clock: 33MHz
capabilities: pci pm msi pciexpress normal_decode bus_master cap_list
configuration: driver=pcieport-driver
*-display
description: VGA compatible controller
product: M76 [Radeon Mobility HD 2600 Series]
vendor: ATI Technologies Inc
physical id: 0
bus info: pci@0000:01:00.0
version: 00
width: 64 bits
clock: 33MHz
capabilities: pm pciexpress msi vga_controller bus_master cap_list
configuration: driver=fglrx_pci latency=0 module=fglrx
*-usb:0
description: USB Controller
product: 82801H (ICH8 Family) USB UHCI Controller #4
vendor: Intel Corporation
physical id: 1a
bus info: pci@0000:00:1a.0
version: 03
width: 32 bits
clock: 33MHz
capabilities: uhci bus_master
configuration: driver=uhci_hcd latency=0 module=uhci_hcd
*-usbhost
product: UHCI Host Controller
vendor: Linux 2.6.24-21-generic uhci_hcd
physical id: 1
bus info: usb@1
logical name: usb1
version: 2.06
capabilities: usb-1.10
configuration: maxpower=0mA slots=2 speed=12.0MB/s
*-usb:1
description: USB Controller
product: 82801H (ICH8 Family) USB UHCI Controller #5
vendor: Intel Corporation
physical id: 1a.1
bus info: pci@0000:00:1a.1
version: 03
width: 32 bits
clock: 33MHz
capabilities: uhci bus_master
configuration: driver=uhci_hcd latency=0 module=uhci_hcd
*-usbhost
product: UHCI Host Controller
vendor: Linux 2.6.24-21-generic uhci_hcd
physical id: 1
bus info: usb@2
logical name: usb2
version: 2.06
capabilities: usb-1.10
configuration: maxpower=0mA slots=2 speed=12.0MB/s
*-usb:2
description: USB Controller
product: 82801H (ICH8 Family) USB2 EHCI Controller #2
vendor: Intel Corporation
physical id: 1a.7
bus info: pci@0000:00:1a.7
version: 03
width: 32 bits
clock: 33MHz
capabilities: pm debug ehci bus_master cap_list
configuration: driver=ehci_hcd latency=0 module=ehci_hcd
*-usbhost
product: EHCI Host Controller
vendor: Linux 2.6.24-21-generic ehci_hcd
physical id: 1
bus info: usb@6
logical name: usb6
version: 2.06
capabilities: usb-2.00
configuration: maxpower=0mA slots=4 speed=480.0MB/s
*-usb
description: Video
product: Acer Crystal Eye webcam
vendor: Acer, Inc
physical id: 1
bus info: usb@6:1
version: 1.00
capabilities: usb-2.00
configuration: driver=uvcvideo maxpower=500mA speed=480.0MB/s
*-multimedia
description: Audio device
product: 82801H (ICH8 Family) HD Audio Controller
vendor: Intel Corporation
physical id: 1b
bus info: pci@0000:00:1b.0
version: 03
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list
configuration: driver=HDA Intel latency=0 module=snd_hda_intel
*-pci:1
description: PCI bridge
product: 82801H (ICH8 Family) PCI Express Port 1
vendor: Intel Corporation
physical id: 1c
bus info: pci@0000:00:1c.0
version: 03
width: 32 bits
clock: 33MHz
capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
configuration: driver=pcieport-driver
*-network
description: Ethernet interface
product: NetLink BCM5787M Gigabit Ethernet PCI Express
vendor: Broadcom Corporation
physical id: 0
bus info: pci@0000:02:00.0
logical name: eth0
version: 02
serial: 00:1d:72:1f:92:73
capacity: 1GB/s
width: 64 bits
clock: 33MHz
capabilities: pm vpd msi pciexpress bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=tg3 driverversion=3.86 firmware=5787m-v3.23 latency=0 link=no module=tg3 multicast=yes port=twisted pair
*-pci:2
description: PCI bridge
product: 82801H (ICH8 Family) PCI Express Port 2
vendor: Intel Corporation
physical id: 1c.1
bus info: pci@0000:00:1c.1
version: 03
width: 32 bits
clock: 33MHz
capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
configuration: driver=pcieport-driver
*-network
description: Wireless interface
product: PRO/Wireless 3945ABG Network Connection
vendor: Intel Corporation
physical id: 0
bus info: pci@0000:04:00.0
logical name: wmaster0
version: 02
serial: 00:1c:bf:ba:7e:16
width: 32 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list logical ethernet physical wireless
configuration: broadcast=yes driver=iwl3945 ip=192.168.1.114 latency=0 module=iwl3945 multicast=yes wireless=IEEE 802.11g
*-pci:3
description: PCI bridge
product: 82801H (ICH8 Family) PCI Express Port 3
vendor: Intel Corporation
physical id: 1c.2
bus info: pci@0000:00:1c.2
version: 03
width: 32 bits
clock: 33MHz
capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
configuration: driver=pcieport-driver
*-usb:3
description: USB Controller
product: 82801H (ICH8 Family) USB UHCI Controller #1
vendor: Intel Corporation
physical id: 1d
bus info: pci@0000:00:1d.0
version: 03
width: 32 bits
clock: 33MHz
capabilities: uhci bus_master
configuration: driver=uhci_hcd latency=0 module=uhci_hcd
*-usbhost
product: UHCI Host Controller
vendor: Linux 2.6.24-21-generic uhci_hcd
physical id: 1
bus info: usb@3
logical name: usb3
version: 2.06
capabilities: usb-1.10
configuration: maxpower=0mA slots=2 speed=12.0MB/s
*-usb:4
description: USB Controller
product: 82801H (ICH8 Family) USB UHCI Controller #2
vendor: Intel Corporation
physical id: 1d.1
bus info: pci@0000:00:1d.1
version: 03
width: 32 bits
clock: 33MHz
capabilities: uhci bus_master
configuration: driver=uhci_hcd latency=0 module=uhci_hcd
*-usbhost
product: UHCI Host Controller
vendor: Linux 2.6.24-21-generic uhci_hcd
physical id: 1
bus info: usb@4
logical name: usb4
version: 2.06
capabilities: usb-1.10
configuration: maxpower=0mA slots=2 speed=12.0MB/s
*-usb:5
description: USB Controller
product: 82801H (ICH8 Family) USB UHCI Controller #3
vendor: Intel Corporation
physical id: 1d.2
bus info: pci@0000:00:1d.2
version: 03
width: 32 bits
clock: 33MHz
capabilities: uhci bus_master
configuration: driver=uhci_hcd latency=0 module=uhci_hcd
*-usbhost
product: UHCI Host Controller
vendor: Linux 2.6.24-21-generic uhci_hcd
physical id: 1
bus info: usb@5
logical name: usb5
version: 2.06
capabilities: usb-1.10
configuration: maxpower=0mA slots=2 speed=12.0MB/s
*-usb:6
description: USB Controller
product: 82801H (ICH8 Family) USB2 EHCI Controller #1
vendor: Intel Corporation
physical id: 1d.7
bus info: pci@0000:00:1d.7
version: 03
width: 32 bits
clock: 33MHz
capabilities: pm debug ehci bus_master cap_list
configuration: driver=ehci_hcd latency=0 module=ehci_hcd
*-usbhost
product: EHCI Host Controller
vendor: Linux 2.6.24-21-generic ehci_hcd
physical id: 1
bus info: usb@7
logical name: usb7
version: 2.06
capabilities: usb-2.00
configuration: maxpower=0mA slots=6 speed=480.0MB/s
*-usb:0
description: Generic USB device
product: DISK 2.0
vendor: USB
physical id: 3
bus info: usb@7:3
logical name: scsi4
version: 12.19
serial: DU7S7G0U74SGFLH8
capabilities: usb-2.00 emulated scsi-host
configuration: driver=usb-storage maxpower=100mA speed=480.0MB/s
*-disk
description: SCSI Disk
product: DISK 2.0
vendor: USB
physical id: 0.0.0
bus info: scsi@4:0.0.0
logical name: /dev/sdc
version: 1219
size: 3824MiB (4009MB)
capabilities: removable
*-medium
physical id: 0
logical name: /dev/sdc
size: 3824MiB (4009MB)
capabilities: partitioned partitioned:dos
configuration: signature=c3072e18
*-volume
description: Windows FAT volume
vendor: MSDOS5.0
physical id: 1
logical name: /dev/sdc1
logical name: /media/UDISK
version: FAT32
serial: 1ab6-e574
size: 3823MiB
capacity: 3823MiB
capabilities: primary bootable fat initialized
configuration: FATs=2 filesystem=fat mount.fstype=vfat mount.options=rw,nosuid,nodev,relatime,uid=1000,fmask=0077,dmask=0077,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8 state=mounted
*-usb:1
description: Generic USB device
product: USB TO IDE
vendor: Genesys Logic, Inc.
physical id: 5
bus info: usb@7:5
logical name: scsi5
version: 0.33
capabilities: usb-2.00 emulated scsi-host
configuration: driver=usb-storage maxpower=96mA speed=480.0MB/s
*-disk
description: SCSI Disk
product: 00JB-00REA0
vendor: WDC WD25
physical id: 0.0.0
bus info: scsi@5:0.0.0
logical name: /dev/sdb
version: 0811
size: 232GiB (250GB)
capabilities: partitioned partitioned:dos
configuration: signature=db6e82f5
*-volume
description: Windows FAT volume
vendor: MSWIN4.1
physical id: 1
bus info: scsi@5:0.0.0,1
logical name: /dev/sdb1
logical name: /media/STOREX
version: FAT32
serial: 10d8-132e
size: 232GiB
capacity: 232GiB
capabilities: primary bootable fat initialized
configuration: FATs=2 filesystem=fat label=STOREXE mount.fstype=vfat mount.options=rw,nosuid,nodev,relatime,uid=1000,fmask=0077,dmask=0077,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8 state=mounted
*-pci:4
description: PCI bridge
product: 82801 Mobile PCI Bridge
vendor: Intel Corporation
physical id: 1e
bus info: pci@0000:00:1e.0
version: f3
width: 32 bits
clock: 33MHz
capabilities: pci subtractive_decode bus_master cap_list
*-pcmcia
description: CardBus bridge
product: PCIxx12 Cardbus Controller
vendor: Texas Instruments
physical id: 6
bus info: pci@0000:0f:06.0
version: 00
width: 32 bits
clock: 33MHz
capabilities: pcmcia bus_master cap_list
configuration: driver=yenta_cardbus latency=176 maxlatency=5 mingnt=192 module=yenta_socket
*-firewire
description: FireWire (IEEE 1394)
product: PCIxx12 OHCI Compliant IEEE 1394 Host Controller
vendor: Texas Instruments
physical id: 6.1
bus info: pci@0000:0f:06.1
version: 00
width: 32 bits
clock: 33MHz
capabilities: pm ohci bus_master cap_list
configuration: driver=ohci1394 latency=32 maxlatency=4 mingnt=2 module=ohci1394
*-storage
description: Mass storage controller
product: 5-in-1 Multimedia Card Reader (SD/MMC/MS/MS PRO/xD)
vendor: Texas Instruments
physical id: 6.2
bus info: pci@0000:0f:06.2
version: 00
width: 32 bits
clock: 33MHz
capabilities: storage pm bus_master cap_list
configuration: driver=tifm_7xx1 latency=57 maxlatency=4 mingnt=7 module=tifm_7xx1
*-system
description: SD Host controller
product: PCIxx12 SDA Standard Compliant SD Host Controller
vendor: Texas Instruments
physical id: 6.3
bus info: pci@0000:0f:06.3
version: 00
width: 32 bits
clock: 33MHz
capabilities: pm bus_master cap_list
configuration: driver=sdhci latency=57 maxlatency=4 mingnt=7 module=sdhci
*-isa
description: ISA bridge
product: 82801HEM (ICH8M) LPC Interface Controller
vendor: Intel Corporation
physical id: 1f
bus info: pci@0000:00:1f.0
version: 03
width: 32 bits
clock: 33MHz
capabilities: isa bus_master cap_list
configuration: latency=0
*-ide:0
description: IDE interface
product: 82801HBM/HEM (ICH8M/ICH8M-E) IDE Controller
vendor: Intel Corporation
physical id: 1f.1
bus info: pci@0000:00:1f.1
logical name: scsi0
version: 03
width: 32 bits
clock: 33MHz
capabilities: ide bus_master emulated
configuration: driver=ata_piix latency=0 module=ata_piix
*-cdrom
description: DVD-RAM writer
product: DVDRAM GSA-T20N
vendor: HL-DT-ST
physical id: 0.0.0
bus info: scsi@0:0.0.0
logical name: /dev/cdrom
logical name: /dev/dvd
logical name: /dev/scd0
logical name: /dev/sr0
version: WP03
capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram
configuration: ansiversion=5 status=open
*-ide:1
description: IDE interface
product: 82801HBM/HEM (ICH8M/ICH8M-E) SATA IDE Controller
vendor: Intel Corporation
physical id: 1f.2
bus info: pci@0000:00:1f.2
logical name: scsi2
version: 03
width: 32 bits
clock: 66MHz
capabilities: ide pm bus_master cap_list emulated
configuration: driver=ata_piix latency=0 module=ata_piix
*-disk
description: ATA Disk
product: WDC WD2500BEVS-2
vendor: Western Digital
physical id: 0.0.0
bus info: scsi@2:0.0.0
logical name: /dev/sda
version: 01.0
serial: WD-WXC108048358
size: 232GiB (250GB)
capabilities: partitioned partitioned:dos
configuration: ansiversion=5 signature=fa66c0df
*-volume:0
description: Windows FAT volume
vendor: MSDOS5.0
physical id: 1
bus info: scsi@2:0.0.0,1
logical name: /dev/sda1
version: FAT32
serial: a20a-9608
size: 9998MiB
capacity: 10000MiB
capabilities: primary fat initialized
configuration: FATs=2 filesystem=fat
*-volume:1
description: Windows NTFS volume
physical id: 2
bus info: scsi@2:0.0.0,2
logical name: /dev/sda2
version: 3.1
serial: a6e0e395-0139-b94d-9056-5118f7616bb6
size: 59GiB
capacity: 59GiB
capabilities: primary bootable ntfs initialized
configuration: clustersize=4096 created=2007-07-14 21:18:31 filesystem=ntfs label=ACER state=clean
*-volume:2
description: EXT3 volume
vendor: Linux
physical id: 3
bus info: scsi@2:0.0.0,3
logical name: /dev/sda3
logical name: /
logical name: /dev/.static/dev
version: 1.0
serial: 60c6b915-91db-4304-b5b5-be1bd97189a5
size: 37GiB
capacity: 37GiB
capabilities: primary journaled extended_attributes large_files huge_files recover ext3 ext2 initialized
configuration: created=2008-04-24 23:25:19 filesystem=ext3 modified=2008-10-19 22:21:40 mount.fstype=ext3 mount.options=rw,relatime,errors=remount-ro,data=ordered mounted=2008-10-19 22:21:40 state=mounted
*-serial UNCLAIMED
description: SMBus
product: 82801H (ICH8 Family) SMBus Controller
vendor: Intel Corporation
physical id: 1f.3
bus info: pci@0000:00:1f.3
version: 03
width: 32 bits
clock: 33MHz
configuration: latency=0[/code]@ vignousse
Pourrais tu éditer ton message afin d’inclure le retour de la commande entre des balises code comme ceci : [ code]ton_texte[ /code] sans les espaces après les [. Ceci afin d’en améliorer la lisibilité, merci. 
Il me semble qu’il manque le début de résultat de ta commande lshw. quelque chose dans ce style:
product: INVALID
vendor: LENOVO
version: Lenovo IdeaPad Y510
serial: NF1Q7CL0160006
width: 32 bits
capabilities: smbios-2.4 dmi-2.4 smp-1.4 smp
configuration: chassis=notebook cpus=2 uuid=00EDE789-96A4-DC81-2F8F-001E8C516966
*-core
description: Motherboard
product: SPEEDY
vendor: LENOVO
physical id: 0
version: 1.0
serial: NS1Q7BL01500367
slot: MIDDLE
*-firmware
description: BIOS
vendor: LENOVO
physical id: 0
version: 06CN23WW (11/20/2007)
size: 64KiB
capacity: 960KiB
capabilities: isa pci pnp upgrade shadowing escd cdboot bootselect edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int17printer int10video acpi usb smartbattery biosbootspecification netboot
*-cpu:0
description: CPU
product: Intel(R) Core(TM)2 Duo CPU T7500 @ 2.20GHz
vendor: Intel Corp.
physical id: 4
bus info: cpu@0
version: 6.15.11
serial: 0000-06FB-0000-0000-0000-0000
slot: Socket 478
size: 2201MHz
capacity: 2201MHz
width: 64 bits
clock: 200MHz
Pour limiter un peu , donne nous plutôt le retour de sudo lshw -C memory
comme le disait saitMoh
et merci pour les balises 
sudo lshw -C memory
*-firmware
description: BIOS
vendor: Phoenix Technologies LTD
physical id: 0
version: V1.32 (02/01/2008)
size: 105KiB
capacity: 960KiB
capabilities: isa pci pcmcia pnp upgrade shadowing escd cdboot acpi usb agp biosbootspecification
*-cache:0
description: L1 cache
physical id: 5
slot: L1 Cache
size: 64KiB
capacity: 64KiB
capabilities: asynchronous internal write-back
*-cache:1 DISABLED
description: L2 cache
physical id: 6
slot: L2 Cache
capacity: 4MiB
capabilities: internal write-back
*-memory
description: System Memory
physical id: 10
slot: System board or motherboard
size: 4GiB
*-bank:0
description: SODIMM Synchronous 667 MHz (1.5 ns)
product: SODIMM000
vendor: Mfg 0
physical id: 0
serial: 1234-B0
slot: M1
size: 2GiB
width: 64 bits
clock: 667MHz (1.5ns)
*-bank:1
description: SODIMM Synchronous 667 MHz (1.5 ns)
product: SODIMM001
vendor: Mfg 1
physical id: 1
serial: 1234-B1
slot: M2
size: 2GiB
width: 64 bits
clock: 667MHz (1.5ns)
Bon, les 4 Gio sont reconnu dans le lshw, c’est déjà ça
Et maintenant quel est le résultat de ces deux commandes :
$ grep HIGHMEM /boot/config-$(uname -r)
$ apt-cache search linux-image bigmem