Hi there

What I'm looking on yours picture looks like is OK,no color discrepancy or other bits,on my DELL U2410 looks OK and seems is fine

Are you using CRT monitor or are you have LED or LCD monitor ?

I know some LED monitors doesn't have proper black(I've one Samsung which is pretty poor,I'm using this as my second monitor and if this is not enough,is not adjustable at all )

Last question can you try save yours render in TIFF,Windows Picture Viewer supports TIFF and TIFF is bit better format and is not loose format as JPG

Please try to save as TIFF and post both renders if you could 

Thanks,Jura