OIC.. My cousin has the Obsidian 650D and he has no heat issues. But then again we live in Canada so its pretty cool in here. ) I have the 300R and I am satisfied with it (cable-management-wise and cooling-wise). Just stick with the 500R then. You'll be happy with it.
CPU+MOBO: there is nothing wrong with ASrock extreme6 i just don't think i would need the extra stuff it already has to the extreme4 but this mobo is a really good deal GIGABYTE GA-Z77X-UD3H - $359.98
or i would choose the big brother GIGABYTE GA-Z77X-UD5H
the first mobo pretty much has the same stuff as extreme4 and the second mobo i put up has 3x PCI 3.0 slots for a triple SLI if you are going to do it
with that fast SSD you have there Samsung 830, you don't really need a fast HDD (WD caviar black) i would go with this SAMSUNG Spinpoint F3
with the promo it is pretty dam cheap, plus you don't really need that high of a cache because of your SSD so you can save a lot of money going with a cheap reliable HDD and a expensive, fast, and reliable SSD
That's a Seasonic built unit and an excellent value.
On the X750 posted first, that's a great PSU. Probably the best performer out of all the PSUs mentioned. There are very good reasons to get it:
-Efficiency means less heat as well as electrical savings.
-Fully modular means if a cable wears out you don't have to RMA the entire PSU. It's also very nice for modders who want to individually sleeve cables. I had a 750TX (original not V2) and the 24-pin connector became loose over time. I had to RMA the whole PSU to get it fixed. Now, Corsair sent me a brand new V2 as a replacement... don't underestimate the value of good support
-The fan profile built into the PSU means that the fan won't even spin most of the time, keeping the build very quiet.
Sorry to muddy the waters, but I do like to educate. I'm sure any PSU you pick will be great. The HX750 is made by CWT.