I already have the 6570 and I know it works perfectly with my setup . . . that's pretty much the only reason why I'm keeping it. 
I'm looking at the i5-3450S, it's only a 65W CPU. Still hot but better than what I have.
I had considered just going with another Sandy Bridge setup like an i3-2105 but the price difference between IB/SB is not very much at all.
That Intel board looks like it would fit if there is sufficient length clearance on the slot "north" of the 16x slot. Certainly better than what I am using now; see attachment.
Your source for everything home theater & HTPC related
If you are going w/ an Ivy Bridge, any particular reason for the discrete video card?
Assuming you are OK w/ the onboard GPU (for HTPC can't see why you wouldn't be) then I would look at the Intel DH77EB myself (I have it and have been fairly happy with it). Stay clear of that Gigabyte board...the Atheros network card is underwhelming to say the least.
Unfortunately most of the "ideal" HTPC Ivy Bridge CPUs are not available yet, i.e. those Core i3\i5 w/ HD4000 (that isn't a -K).
Mikinho | Missing Remote | Windows Entertainment and Connected Home MVP