Hello, I'm working on a new build with the i5-3550, and have a couple of options available for mobos:
One option is a B75 chipset
The other features a z77 chipset
Not really sure of the differences, I'm targeting a <$1000 build with no plans to OC. I'll be using the system mostly for gaming.
I know this has already been answered above, but the 2 main differences are:
The Z77 chipset has 2 SATA6 ports and 4 SATA3 ports, the B75 chipset only has 1 SATA6 port and 5 SATA3 ports
The Z77 supports overclocking, the B75 does not.
There are other differences, but these are the most important IMO.
None of this probably matters to you and the B75 is almost certainly fine for 99% of people.
Disclaimer: My PC is an ASRock B75 m-itx motherboard with Intel i5 3330S processor.