HELP "Overlocker ma ram" HELP

Bonjour, vu que j'ais des soucis avec ma ram (8go installé mais 4go utilisable) j'aimerais

overlocker ma ram.Voici ce que j'ais comme RAM : http://www.ldlc.com/fiche/PB00095844.html

Et voici ma config:

Windows 7 Edition Familiale Premium (x64) (build 7601) Service Pack 1
Navigateur web par défaut: Google Chrome
Client e-mail par défaut:
WinSAT
Note Générale 5.9 (Processeur: 7.4, Mémoire vive: 7.4, Graphiques: 7.8, Graphiques de jeu: 7.8, Disque dur principal: 5.9 )
Carte mère
SMBios version 2.6
ASUSTeK Computer INC. P7P55D Rev 1.xx
Bios: American Megatrends Inc. 2003 12/14/2010 taille: 2048Kb
Chipset
Northbridge: Intel DMI Host Bridge
Southbridge: Intel P55
Processeur
Intel Core i7 860 Lynnfield Socket 1156 LGA (@45 nm) 2800 Mhz ( L1I: 4 x 32 Ko, L1D: 4 x 32 Ko, L2: 4 x 256 Ko, L3: 8192 Ko )
Mémoire
Mémoire physique totale: 8192 Mo, Type: DDR3, @933.3MHz, 9.0-9-9-24-2T
DDR3 Corsair CMD8GX3M4A1333C7 2048 Mo PC3-10700H (667 Mhz)
DDR3 Corsair CMD8GX3M4A1333C7 2048 Mo PC3-10700H (667 Mhz)
DDR3 Corsair CMD8GX3M4A1333C7 2048 Mo PC3-10700H (667 Mhz)
DDR3 Corsair CMD8GX3M4A1333C7 2048 Mo PC3-10700H (667 Mhz)
Carte Graphique
Radeon HD 5870 (RV870,,1024 Mo)
Périphériques ATA
SAMSUNG HD103SJ 1AJ100E4 (SATA II, 931.51 Go, Cache: 31 Mo)
SAMSUNG HM500LI 2TF00_00 (SATA II, 465.76 Go, Cache: 8 Mo)
Lecteurs CD/DVD
DTSOFT Virtual CdRom Device
DTSOFT Virtual CdRom Device
TSSTcorpCDDVDW SH-S223C SB01 (DVD+R/DL Recorder)
Disque dur
SAMSUNG HD103SJ ATA Device
SAMSUNG HM500LI SCSI Disk Device
Cartes PCI/AGP
Stockage
Intel Corporation:5 Series/3400 Series Chipset 4 port SATA IDE Controller:
Intel Corporation:5 Series/3400 Series Chipset 2 port SATA IDE Controller:
JMicron Technology Corp.:JMB362/JMB363 Serial ATA Controller:

Réseau
Realtek Semiconductor Co., Ltd.:RTL8111/8168B PCI Express Gigabit Ethernet controller: M4A785TD Motherboard

Affichage
ATI Technologies Inc:Radeon HD 5870 (Cypress):

Multimédia
Intel Corporation:5 Series/3400 Series Chipset High Definition Audio:
ATI Technologies Inc:Cypress HDMI Audio [Radeon HD 5800 Series]:

Ponts
Intel Corporation:Core Processor DMI:
Intel Corporation:Core Processor PCI Express Root Port 1
Intel Corporation:5 Series/3400 Series Chipset PCI Express Root Port 1
Intel Corporation:5 Series/3400 Series Chipset PCI Express Root Port 5
Intel Corporation:5 Series/3400 Series Chipset PCI Express Root Port 6
Intel Corporation:5 Series/3400 Series Chipset PCI Express Root Port 7
Intel Corporation:5 Series/3400 Series Chipset PCI Express Root Port 8
Intel Corporation:82801 PCI Bridge
Intel Corporation:5 Series Chipset LPC Interface Controller:
Intel Corporation:Core Processor QuickPath Architecture Generic Non-Core Registers:
Intel Corporation:Core Processor QuickPath Architecture System Address Decoder:
Intel Corporation:Core Processor QPI Link 0:
Intel Corporation:Core Processor QPI Physical 0:
Intel Corporation:Core Processor Integrated Memory Controller:
Intel Corporation:Core Processor Integrated Memory Controller Target Address Decoder:
Intel Corporation:Core Processor Integrated Memory Controller Test Registers:
Intel Corporation:Core Processor Integrated Memory Controller Channel 0 Control Registers:
Intel Corporation:Core Processor Integrated Memory Controller Channel 0 Address Registers:
Intel Corporation:Core Processor Integrated Memory Controller Channel 0 Rank Registers:
Intel Corporation:Core Processor Integrated Memory Controller Channel 0 Thermal Control Registers:
Intel Corporation:Core Processor Integrated Memory Controller Channel 1 Control Registers:
Intel Corporation:Core Processor Integrated Memory Controller Channel 1 Address Registers:
Intel Corporation:Core Processor Integrated Memory Controller Channel 1 Rank Registers:
Intel Corporation:Core Processor Integrated Memory Controller Channel 1 Thermal Control Registers:

Système
Intel Corporation:Core Processor System Management Registers:
Intel Corporation:Core Processor Semaphore and Scratchpad Registers:
Intel Corporation:Core Processor System Control and Status Registers:
Intel Corporation:Core Processor Miscellaneous Registers
Intel Corporation:Core Processor QPI Link
Intel Corporation:Core Processor QPI Routing and Protocol Registers

Bus Séries
Intel Corporation:5 Series/3400 Series Chipset USB2 Enhanced Host Controller:
Intel Corporation:5 Series/3400 Series Chipset USB2 Enhanced Host Controller:
Intel Corporation:5 Series/3400 Series Chipset SMBus Controller:
VIA Technologies, Inc.:VT6306/7/8 [Fire II(M)] IEEE 1394 OHCI Controller: M4A series motherboard
Périphérique USB
Microsoft Corp. Xbox 360 Wireless Adapter (Xbox 360 Wireless Receiver for Windows)
Logitech, Inc. Logicool HID-Compliant Keyboard (106 keys Ctrl+Caps) (Périphérique USB composite)
Logitech, Inc. Logicool HID-Compliant Keyboard (106 keys Ctrl+Caps) (Périphérique dentrée USB)
Logitech, Inc. Logicool HID-Compliant Keyboard (106 keys Ctrl+Caps) (Périphérique dentrée USB)
Périphérique USB composite
Périphérique dentrée USB
Périphérique dentrée USB
Périphérique dentrée USB
Intel Corp. Integrated Rate Matching Hub (Generic USB Hub)
Intel Corp. Integrated Rate Matching Hub (Generic USB Hub)
Clavier
Périphérique clavier PIH
Périphérique clavier PIH
Souris
Souris HID
Souris HID
Ecran(s)
Moniteur Plug-and-Play générique(Samsung SAMSUNG)