Not sure why your first thread died, though I think I still had thoughts to add but didn't have the time
If you've settled on ITX, the first build looks preferable. That i5 will beat the piss out of the Athlon X4 with it's lack of L3 cache, overclocking or no, and there's no need for a 600w PSU (especially a badass Silverstone unit) unless you're using a top-end GPU; my dual-HD6950 2GB cards and firstname.lastname@example.orgGHz only use about 500w at the wall under max load, as a personal example. If you look through GPU reviews here at TR and over on Anandtech (for comparison), you'll find similar power usage levels recorded.
That being said, the only hole I see is the HSF, and I'm not sure how to tackle that one in the SG-05. Some people have used Corsair's H50 (and I assume the H60 will work similarly) to replace the front intake fan, though that requires modification and limits storage, while others just use Silverstone's NT-06
. My idea was to use the NT-06 and mount a 120mm fan underneath it, possibly by flipping the fan mount/shroud around, but I never got to test it and see if it was even possible myself. A person named 'Shooter at the top of the second feedback page says he was able to flip the mount over and put in a slim Scythe 'Slipstream' slim fan however, and another reviewer mentions that there's enough clearance for a 25mm-thick fan (can't fine a 'slim' sub-25mm thick 120mm fan on Newegg?) with the mount/shroud inverted. If it can be verified that the memory will still fit with this thing installed, then I think that's probably your best bet.
Scratch that. Every ITX SNB board on Newegg (except an errant Foxconn) has the CPU socket next to the PCIe slot and close to the RAM slots, so cooling options are highly
limited. Looks like it will probably be the stock HSF or an integrated watercooler, if you can make it fit.
I will add that since there's extra cost to be considered with any extra cooling solution, I'd recommend just using the stock Intel HSF, being aware that if you do decide to get another HSF afterwards you will
be disassembling and reassembling your system to install it.