based on its specification: http://www.samsung.com/my/consumer/pc-peri...4B350HS/XM-spec

its max resolution is 1920x1080. thats it. i can't displayed more than that.
they have 1920x1200 24" led monitor: http://www.samsung.com/us/computer/monitor...A850DW/ZA-specs
but it is not available in our region. i don't know why.

what do you mean by a black borders? is that just horizontal, or vertical? or both? when it happened? while watching movies, playing games, or your desktop itself already filled with black borders?

If your monitor can't automatically detect the resolution perceive and adjust accordingly then you have to use the monitor mode to force the screen to full screen either 16:9 or 4:3, most of the current monitor should have this function if the monitor can't do automatic.
Also you can try to set the resolution to the monitor native resolution before you force the monitor to full screen.

i never use samsung lcd/led so i cannot imagine, but can you access the panel menu and find a menu that can reset the display, or similar tu full screen or 1:1 pixel mapping or something like that? 
seems like your monitor's settings cause that borders since you are saying that you saw that black borders when starting the pc, not after booting into windows. means they are nothing to do with graphic driver.

anyway, are you using vga/d-sub port or hdmi?

edited: i just downloaded your lcd model's manual. according to the manual, it has "optimal resolution setting" and "standard signal mode table". i think your lcd are using 4:3 mode and not 16:9, thats why you saw the borders. try setting to VESA 1920x1080 with 60Hz mode.