ATI Radeon 4870 x2 HELP!

[Sik-End]

im having a problem with my 4870. every time i try to play a game higher than the low settings it crashes my computer. i can play the games higher as long as they're in windowed mode like crysis i can play full spec in windowed as soon as i go full screen it crashes. here's what i got:

-MSI 790FX-GD70 AM3 AMD 790FX ATX AMD Motherboard
-VisionTek 900250 Radeon HD 4870 X2 2GB 512-bit
-Antec TruePower New TP-750 Blue 750W Continuous Power ATX12V V2.3 / EPS12V V2.91 SLI Certified CrossFire Ready 80 PLUS BRONZE
-AMD Phenom II X4 955 Black Edition Deneb 3.2GHz Socket AM3 125W
-G.SKILL Perfect Storm 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 2133 (PC3 17066)
-Western Digital Caviar Black WD1001FALS 1TB 7200 RPM SATA 3.0Gb/s 3.5"
-Logitech G19 Black USB Wired Standard Gaming Keyboard
-ASUS VW266H Black 25.5" 2ms(GTG) HDMI Widescreen LCD Monitor
-Microsoft Windows Vista Ultimate SP1 64-bit
-XIGMATEK Dark Knight-S1283V 120mm Long Life Bearing CPU Cooler

all of this is in an Antec 1200 case. and one problem i have with the memory is that it wont fit in my dimm 1 slot due to the massive heatsink for my CPU.

 

[OvrClkr]

How much memory (RAM) does your PC have installed at the moment?

 

[Sik-End]

its 6 gigs but its clocked at 1333 i havent overclocked yet cause i dont wanna void any warrenties till its fixed.

 

[OvrClkr]

Ok, have you flashed your bios to the latest update?

What Ati Drivers are you using?

Have you used the Catalyst software to change the values to your desired level?

What resolution are you currently at?

 

[Sik-End]

no i havent flashed the BIOS

I'm using the adm drivers all up to date

i have not changed the clock speed but i did change the 3d settings

1920x1200

my biggest concern is when it was first installed there was a small whisp of smoke so i'm currently getting a replacement but iv had other systems that did that but work just fine. it was just a peice of dust ignigting or something. and if i flash the bios i have to reinstall windows right?

 

[OvrClkr]

Smoke? That is not good at all..... 😱

If you flash the Bios you DO NOT have to reinstall windows... Everything stays the same.... The only difference is that you will be fully updated and may be able to install the latest hardware w/o any issues...