Dell S2440L Monitor different on mac and PC

[jwatts747]

I have a Dell S2440L Monitor which I use for both a PC i've built, and a Macbook Air 11" 2011 Model. The resolution seems to be much worse when i connect it to my PC and I can't figure out why, can anyone help?

 

[kanewolf]

How do you connect them to the respective computers (DVI, HDMI, VGA, etc)?

 

[jwatts747]

PC - HDMI
MacBookAir - displayport (out) to hdmi (in) adapter