I am planning on buying a second fan for this to do push/pull and I was wondering if I needed to get some kind of splitter to connect both fans to the cpu fan connector on my mobo (ASUS sabertooth x58).
yes you would unless your mobo somehow has 2 CPU fan connectors...
a splitter would be the best bet....if you are using newegg.com or newegg.ca just search Gelid they have a good PWM fan splitter i love it works perfectly for my HAF 922 case and Hyper 212+ push/pull setup
I can always tie away any excess, so its not a big deal to me.
Maybe you can help with another question I have:
I plan on getting an 80 mm fan for an exhaust on the top of my fan.
Should I be plugging this into either the NB fan connector on my mobo or a different fan connector? Or simply use the 4 pin connection into my PSU?