The game should support that resolution natively, though :?
Did you try to edit config.ini in My DocumentsCAPCOMRESIDENT EVIL 5 ?
What adjustments might fix it?
Mines zoomed in with top and bottom cropped Vert-
Heres
config.ini
[GAME]
MouseBaseSpeed=2.000000
[GRAPHICS]
SLI=OFF
Stereo=OFF
HDR=LOW
MSAA=NONE
TextureFilter=ANISOTROPIC16X
TextureDetail=HIGH
MotionBlur=OFF
NormalMapping=ON
NormalUpdate=ON
Specular=ON
Lighting=HIGH
FilterQuality=HIGH
WaterQuality=HIGH
EffectQuality=HIGH
EffectVolume=HIGH
ShadowQuality=HIGH
LOD=HIGH
Joint=HIGH
Adhesion=HIGH
[DISPLAY]
Resolution=5760x1200
RefreshRate=60Hz
FullScreen=ON
VSYNC=OFF
AdjustAspect=OFF
FrameRate=VARIABLE
[SOUNDS]
SeVoiceNum=128
ReverbQuality=LOW
CategoryEQ=ON
[CPU]
JobThread=7
RenderingThread=ON
[JOYPAD]
A=2
B=1
X=3
Y=0
LEFT=15
RIGHT=13
UP=12
DOWN=14
START=9
BACK=8
LT=4
LB=6
RT=5
RB=7
LSTICK_PUSH=10
LSTICK_VERT=Y
LSTICK_HORZ=X
RSTICK_PUSH=11
RSTICK_VERT=Z
RSTICK_HORZ=RZ
Maybe AdjustAspect=OFF???