Thanks guys!
I had a bit of a problem in the meantime which could turn into a disaster. One of the PSU cables that fed the bottom card fried during a 3DMark run. Literally. The system shut itself, ASUS GRYPHON board giving a surge protection error! It turned out that the cable had bad contact where it connected the PSU, it fried and melted the connector and welded itself on the PSU. Took me some muscle to get it out of the PSU.
Good news was that nothing got affected. I guess I'm blessed. It could fry anything and everything, I guess if it wasn't for that surge protection, which I didn't even know existed. I tested all the components, everything including the PSU is working fine. Still, I replaced the PSU with a Seasonic 860 Platinum, to be on the safe side and to give a little headroom for overclocking, and it was the right decision.
Cards individually were stable folding at 1200MHz max, which was basically +50MHz on top of their factory OC, and now they're both running at that speed.
With the ASUS Z87-i Deluxe, the CPU was not stable beyond 4.5GHz, and this GRYPHON board impressed me as it's rock solid at 4.6GHz. On top, the memory is now stable with 2200MHz, with 10-10-10-30-1 timings; it had topped at 2000MHz before. Mind you, this little Crucial kit is 1600MHz 8-8-8-24-2 stock! Both the memory and the board impressed me beyond words.
Finally, I added another(!) 120mm fan on top of the rad closer to the PSU and it did wonders to bottom GPU temps. It used to run 3-5C warmer than the top card, now it runs 3-5C cooler! Plus, the same card's VRM temps got dropped by a good 6-7C, and now both cards VRM temps run the same.
Don't ask how I could fit that fan in that tight spot though... it was tough to say the least, but now the system is running like a champ!
*knocks on wood*
I'd like to say kudos to Crucial and ASUS! I had already liked Crucial, hence I had upgraded to the Crucial MX100 SSD to match the memory. Glad to support them
. Well, of course, thanks to ASUS for releasing a board matching my alias, and making it rock solid!
I'll update the pics in the OP but for now, I'll share this: