Is there something specifically better about the Sabertooth's BIOS? Remember you're only going to be spending around 10 minutes maybe when you first set up the computer, and then an hour or two when you're actually overclocking it in there. For the rest of the 3 years or so of the computer's lifetime, the BIOS will be completely irrelevant (unless it allows you to overclock better, which would surprise me).
Personally I would never rely on just one source when buying computer parts. Having said that, I admit those videos are interesting, since what every computer enthusiast has been hearing for some time now is Intel > AMD. A couple of things about those videos stand out to me as slightly odd though:
A) The number of games he's using is quite limited, and there's a lot of overlap between the two videos, meaning the overall sample of games is like 5-6 titles: (Far Cry 3, Skryim, Crysis Warhead, Crysis 2, Trine 2 and ArmA 2 are the (fairly) modern ones -- I'm ignoring Black Mesa, since Source is a very old engine). Of these titles the i5 is better in Crysis 2 and Skryim
according to his benchmarks. Like I said before, I never put all my eggs in one basket. The results between the two videos are even contradictory at points (in the first video Metro 2033 runs better on the AMD, yet in the second Metro 2033 is faster on every benchmark -- he seemingly quotes "new drivers" as being the reason, which given that CPUs don't have drivers, I find it a little strange).
B) He uses mid-range graphics (mostly talking about the 7870 here) rather than the usual CPU bench-marking strategy, which is to use the best GPU possible, so it has as little of an effect on gaming performance. This leaves him very prone to bottlenecking, esp. at 1440p, which in turn tends to churn out anomalous results (well perhaps not anomalous, but who games at 1440p on a 7870??). You might say well this "approximates a real world system better", which is valid and perhaps true (again no one would use a 7870 at 1440p...), but it doesn't apply to you, since you're getting a 7970
at the very least. There are other benchmarks with systems much closer to your planned one that would be better to look at I think.
C) He includes the streaming performance as a metric. Streaming is a very multi-threaded task (which is why the i7 is recommended a lot for streamers). Unless you're planning on streaming, I wouldn't take this into consideration.
D) On the topic of what games he's chosen, he says he prefers "independent stuff because they are less likely to optimize their stuff for Intel over AMD" (at least this is why he's included Trine 2/Black Mesa, though I think ArmA 2 probably falls into this category, since it's really just a badly optimized game all-round).
This argument is completely backwards. Surely if all the big titles are being optimized for Intel, you should buy Intel, rather than buying AMD and saying, "well it's only because games are well optimized for Intel that I get worse performance". As a gamer, all you care about is the best performance on the titles you play, it's of no concern to you that your performance "should be better, if the game was better optimized for your hardware", the fact is it simply isn't.
Now let's look at the games where the i5 is faster:
Crysis 3 (close, but the FX has a lower minimum frame rate):
http://www.tomshardware.com/reviews/crysis-3-performance-benchmark-gaming,3451-8.html
Total War 2 (and Skyrim, but we already know that it's faster on Intel):
http://www.bit-tech.net/hardware/2012/11/06/amd-fx-8350-review/6
Batman AC:
http://www.techradar.com/reviews/pc-mac/pc-components/processors/amd-fx-8350-1110369/review
ArmA II (again conflicting results):
http://www.behardware.com/articles/880-13/amd-fx-8350-review-is-amd-back.html
F1 2012:
http://www.behardware.com/articles/880-14/amd-fx-8350-review-is-amd-back.html
Far Cry 3 (again conflicting results, notice though that this benchmark is using a 7970 -- which is your planned setup -- whereas the video used a GTX 670):
http://www.techspot.com/review/615-far-cry-3-performance/page6.html It's only by 1 FPS compared to a i5-3470 (just a slower i5-3570K), but it does seem to shed some doubt on his benchmark where the FX had nearly double the FPS.
So that's why I think unless you only play Crysis Warhead and Trine the i5 is probably a better bet. There might even be benchmarks out there showing that these perform better on Intel too, you never know! My point is never rely on benchmarks from only 1 source. I've made that mistake in the past, and I ended up with a terrifically noisy graphics card.
I'm not saying the FX isn't viable, I just personally think that generally, across the board the i5 is stronger.
M