21" iMac & Dell Dual Screen problems with resolution

I have been running a i7 2011 iMac for a while now and decided i want to dual screen to help with my photo editing and music production.

After a while searching i decided to buy a Dell Ultrasharp IPS (Model: U2212HM). I have been able to connect it via VGA but was having problems with DVI..

So after leaving it connected to VGA i decided i wanted to up the resolution to 1920x1080. The manual says insert the CD for instructions on how to.. After googling it and searching for a few hours i still can't figure out how to..

Anybody have any input?

Much appreciated,

AdrianK said:

Have you tried going to System Preferences > Displays > Choosing 1920*1080 on the window displayed on the Dell monitor?

EDIT: The monitor has a DisplayPort connector, you can connect it to your iMac via a mini DisplayPort to Display port cable. You'll get better quality than VGA and the cables are pretty inexpensive (compared to adaptors).

Click to expand...

For some reason the past few times i have went into System Preferences > Displays is hasn't came up on the Dell monitor but i just restarted my iMac again and tried it and it came up the second time i tried..

Thanks for the advice as i knew it would be something simple but it was giving me a sore head not being able to figure it out..

As for the adapter i will be buying one soon as i didn't know the monitor had one when i bought it.. So i will be buying it soon.