Hi, I have some questions about this variation, is this really unsound? cause i have problem to crack it with white

Here, the most popular move is taking on c6, but is it really the best move? Black has 2 bishops and half opened B file, so why white should be preferable here?

Look at the position.  Why benefits accrue to white by playing Bxc6? Are the benefits you list for black real or apparent, short term or long? The half open b-file offers no points of entry and cannot be exploited.  The two Bishops aren't going anywhere.  The black bishop can't move!  Black's pieces are tangled in the first two rows.  Where does he go?  What does he do?  All he can do is wait on White, hoping he overextends himself while exploiting black's cramped, albeit solid position.  White has the better pawn structure, more space, opportunities on the King side, Knights to move around the fixed and targetable Bishops (they aren't outrunning anybody for awhile) to have fun with. 

Main line variations are rarely unsound, and once they are discovered to be unsound they are dropped fast and then no longer main line.  On the other hand it is sometimes difficult to understand why some moves are considered good.  As Black I'd rather 3. ...a6 then 4... d6 but some people are really afraid of 4. Bxc6 and others just like cramped positions.

And others think that white is threatening to win e5 pawn immediately, so they defend it by the pawn. :)

Thx for your explanation, I didnt appreciate initiative white has

20 years ago they said the same about the Berlin but look now, everyone and their granny play the Berlin.

I think steinitz is a decent system for our level and on top of that it is easy to grasp its concepts.

2c

Which move order are you considering in the Steinitz? The straight Steinitz is tough to crack  but generally inferior since Black is forced to surrender the center with 7...ed4 (Tarrasch Trap) but the Steinitz deferred avoids that and gives a solid game. The lines with g6 even give counterplay at the cost of a little weakness. The Berlin order gives Black some other ways to get into sound positions without worrying about the Exchange variation. So in all I agree with you about soundness. It's just a matter of solidity vs. counterplay (or lack of). FM Steve Stoyko

I could've sworn though that this was in my system and nimzowich thought white had no advantage but Tarrasch did. I forgot why he said that though, but I think it was something about how white's game only looks freer. But then he also thought that in the french 1 e4 e6 2 d4 d5 3 Nc3 was a mistake because ...dxe4 is supposed to be so good. To me though, it looks like if anyone has the chances, it's white, it's just hard to crack.

In the main line Steinitz the White edge can evaporate quickly thru exchanges - that is why people have trouble playing it for White. This is not an attacking position at all - Black has no King side weaknesses, just space. The move f2-f4 at  any time makes the e-pawn weak on the open e-file.

I suggest the following - Bf1 (to avoid 2 exchanges) in my mind is clearly better then Bc6 (which does the same but costs a B). Bg5 just invites potential exchanges. Bc4 puts the B on an ambiguous square. So why Bf1? It opens up g3 and Bg2 to reinforce the e pawn and make it almost impossible foe Black to play d6-d5 in the future.

Then play b3 with Bb2 before attempting Nd5. Prep Nd5 with Rad1. This formation causes Black big problems. To expell the N with c6 is asking the d-pawn to commot suicide.

After all this is accomplished THEN White can consider expanding on the K-side.

Note: if Black plays Nd5 after White has played c2-c4 take back with the c-pawn an attack down the c-file into c7. Taking with the e-pawn is very drawish. Taking with the Queen is better for White but all the piece exchanges have helped Black.

Bf1 seems to give white more winning chances, though the black knight on c6 on the other hand could be better than the bishop going to g2!

But I totally agree with the plan, Steve-Stoyko. If white can prevent black from ...d5, then he can just keep building up while black can only really attack e4 or control e5, but that's not a real outpost because of a well timed f4.