ATI 4890 lagging then crashing

I recently got a new computer from cyberpower. It was good the first few days but then it would randomly get blue screens. I ran a diagnostics test and it said it was something wrong with my RAM. After that i stopped getting blue screens and ran a diagnostics test and it could find nothing wrong. It was working well for about two weeks, but when i was playing far cry 2 today it started lagging so i reset my computer. It would start up for about 5 seconds then would just shut down and nothing would appear on the screen. I let my comp sit and i tried it again later and it was working. I loaded up the sims 3 and it was very laggy witch it never has been. I tried to play on the crysis sandbox editor but my computer shut down right away when it was about to load up the map. I also was hearing a wierd noise from my graphics card last night. Is my graphics card dying or is something else? I'll post my specs. Please help. Thanks.

CPU: Intel® Core™ i7-920 2.66 GHz 8M L3 Cache LGA1366
CD: (Special Price) LG 20X DVD±R/±RW + CD-R/RW DRIVE DUAL LAYER (BLACK COLOR)
CD2: 16X DVD ROM (BLACK COLOR)
FA_HDD: None
FLASHMEDIA: None
FAN: Asetek Liquid CPU Cooling System (Extreme Cooling Performance + Extreme Silent at 20dBA)
FREEBIE_RM: None
FLOPPY: NONE
FREEBIE_OS: FREE! (Halo 2) Game
HDD: Single Hard Drive (1TB (1TBx1) SATA-II 3.0Gb/s 16MB Cache 7200RPM HDD)
HDD2: NONE
IEEE_CARD: NONE
KEYBOARD: XtremeGear (Black Color) USB Keyboard
MOUSE: XtremeGear Optical USB 3 Buttons Gaming Mouse
MODEM: NONE
MULTIVIEW: Non-SLI/Non-CrossFireX Mode Supports Multiple Monitors
MONITOR: NONE
MONITOR2: NONE
MOTHERBOARD: GIGABYTE X58 GA-EX58-UD3R 2 WAY CROSSFIRE/SLI DDR3
MEMORY: 6GB (2GBx3) PC1333 DDR3 PC3 10666 Triple Channel Memory (Corsair or Major Brand)
NETWORK: Onboard Gigabit LAN Network
OS: Microsoft® Windows Vista™ Home Premium w/ Service Pack 1 (64-bit Edition)
PRINTER: None
PRINTER_CABLE: None
POWERSUPPLY: 1,000 Watts Power Supplies [+30] (Azza Gaming Active PFC Power Supply SLI/CrossFire Ready)
RUSH: NO; READY TO SHIP IN 5~10 BUSINESS DAYS
SERVICE: STANDARD WARRANTY: 3-YEAR LIMITED WARRANTY PLUS LIFE-TIME TECHNICAL SUPPORT
SOUND: HIGH DEFINITION ON-BOARD 7.1 AUDIO
SPEAKERS: NONE
TEMP: NONE
TVRC: None
USB: Built-in USB 2.0 Ports
USBHD: NONE
VIDEOCAMERA: NONE
VIDEO: ATI Radeon HD 4890 1GB DDR5 PCI-Express Dual DVI-I & TVO