I don't know what kind of crap computer you are using, but my mobile phone running Stockfish 6, found the move as soon as I started the engine. It was the first and only move recommended.
I just had an idea. Possibly check your engine options for Stockfish 6 and make sure you have it playing at full strength. Possibly you had the engine strength turned down so you could play against it and have a chance.
I used Stockfish 6 in chessbase 12 so there is no playing strength option as far as I am aware. Its not a chess playing program its a database.
This is strange then it could be my bad computer. Must mean my comp is utter crap if a mobile phone can beat it.
That is interesting, it really takes stockfish long time to find that move and after that it thinks it is completely crushing.
Here is FEN, if someone wants to try it out: q1r1k2r/1b3pp1/p3p3/P1b4n/1pN1P2p/3BBP2/1P2Q1PP/R4R1K b - - 0 1
I'm also using high end pc so that isn't the case.
Stockfish 4 took about 2 minutes here. And I just downloaded Stockfish 6, and it took about 4 minutes. Both 64 bit versions of the engines on Arena and a basic 4 year old laptop.
Also I personally don't find the tactic that easy 
Edit: I appearantly overlooked the double rook sac threat, after the quiet 3...Ke7. Nice combo!
Stockfish 6 64 took about one minute to find 1...Ng3+.
That's a good one. Komodo 9.1 took twenty-one seconds, and then about two seconds more to realize the move was crushing.
It doesn't matter if it's chess base 12, there's still options for the engine parameters. Here's my set up on mobile phone that I used for this topic: Analyze This Pro, chess app available from Android store, comes with Stockfish 6. I also purchased Komodo 9.1 to run with this also. And just for the record, Komodo 9.1 on my mobile phone sees the move immediately as well. I've used previous versions of Chess base, and I run engine matches extensively, it's one of my hobbies. I'm just kidding about your computer, but the software environment the engine runs in can have a big effect on the engine performance. So, once again, take some time looking into your engine options and make sure the engine strength is set to maximum.
At least I have my chess engine set to 100% strenght. I find it hard to believe that your smartphone is outcalculating my intel i7 prosessor...
Chessbase 12 does have UCI engine configuration options. By default Stockfish uses only one CPU core.
Using four cores here (an old, slow Athlon II X4 640) it took about 15 seconds to find Ng3+, but I'm using a recent devel version of Stockfish.
Komodo 9.2 needed almost 40 seconds.
Welcome to the strange world of move pruning- this is how all modern engines are working: Some "inferior" moves are not considered at all initially.
Here's my set up on mobile phone that I used for this topic: Analyze This Pro, chess app available from Android store, comes with Stockfish 6
I use Analyze This Pro (love it! :-) ) with Stockfish 6 too, and it appears to be a bit faster than my laptop, but it still takes over 3 minutes. Critter 1.6 needs about 1 minute on my phone to find the move .
Chessbase 12 does have UCI engine configuration options. By default Stockfish uses only one CPU core.
Using four cores here (an old, slow Athlon II X4 640) it took about 15 seconds to find Ng3+, but I'm using a recent devel version of Stockfish.
Komodo 9.2 needed almost 40 seconds.
Welcome to the strange world of move pruning- this is how all modern engines are working: Some "inferior" moves are not considered at all initially.
Great point. I'm not sure if Stockfish 6 has parameters to adjust its move pruning, but Komodo 9.1 does.
No, you cannot turn pruning off in Stockfish.
Komodo 9.X does have an option to disable pruning (needless to say the engine becomes much slower if tuned like that) as well as saving the hashfile for future usage.
By default Stockfish uses only one CPU core.
Took me 9 seconds after adjusting this.
I will add one more thing. The app, Analyze This Pro, is an app that is specifically designed for analyzing, and, as such, it is designed to run FAST. It's definitely the fastest app of all the apps I use for analyzing. However, I also checked a couple other apps I use for analyzing, including Chess PGN Master Pro, and the mobile version of SCID, they all see the winning move immediately as soon as I start the engine. Hell, I even switched to Bikjump 2.1 engine just for fun, and it also finds this move immediately. So my advice is to ditch your computers and purchase a $100 Kyocera icon mobile Android phone, rotflmao!
Guess what? My copy of Stockfish - the latest Timestamp: 1446458743 - suggested Queen to a7! 
I had to put it into Infinite Level (in Arena 3.0) and let it run before it decided on the right night move... how's that! 
62s with Droidfish, wtf was that. :-)
