Help me understand the Qeens Gambit Accepted line

I am also having trouble understanding why stockfish says that black is winning after move 8 in the sideline i've calculated - white has only invested a tempo to capture that pawn, perhaps another one if he decides to retreat the rook..

Thanks for your answers. The advantage seems to be dynamic and in both cases, one have to develop quickly and play active moves to keep the advantage. 

I'll do some study of what to do as both white & black in the first case (at move 5). I play queens gambit & slav defense quite a lot but i almost never get into the gambit accepted line so it is new for me.

vlad kramnik used to play thes positions in 90s, check database

even if black hold extra pawn, this is only advantage of him, and then by defending this it may end into very poor and pasive position

Glad to help.  If you're serious about improvement.  Then start using chess engines ONLY to check for blunders, and missed tactics.  Using an engine to try and figure out why something is +/- .7 of a pawn is a waste of your study time.

There is no materially different theme than what is widely known why you cant hold the pawn in QGA.

Basically a lot of that is the pawn grabber mentality. The good news is its easy to fix since the pawn grabber in this case easily gets crushed as a surprise to them.

As far as engines go, after 6 Nc3, the engine gives 6...Qb6. If that doesnt tell you something, then dont use engines yet. But it immediately says 'Im using 9ish pts of material to defend 1 pt and thats my only option'. Its a mop up operation for white.

Is it obvious that White's "lead in development" and Black's "whole mess of weaknesses" outweighs the pawn? In 1997, GM Matthew Sadler wrote about 1 d4 d5 2 c4 c6 3 Nf3 dxc4 and he did not seem to be very confident of the correct evaluation: "... amongst others, [this Miles-Hodgson game https://www.chessgames.com/perl/chessgame?gid=1098636 ] put the line under a cloud. It is so unbalanced, however, that I would not be at all surprised if there is a sneaky resource for Black! …"

Is there an engine setting that causes them to "ONLY" comment on blunders and missed tactics? Anyway, is there anything wrong with wondering about a +1 evaluation for a position where White is a pawn down?

That's an interesting way of putting it, i haven't really thought about it this way. I've checked a few engine lines and it seems that white gets his compensation with interest, if you know how to capitalize on blacks play. QGA may be well known but this is the first time i actually study it.

I am aware of that line. There is a huge difference in my game compare to that one: Black played c6 on his second move and white played nf3 on his third move. 

6.. Bf4 ?? is blunder ( Did not you see massive evaluation drop of Stockfish from white favour to black favour)

White throw up a tempo to attack c4 and b5 pawn ( black can develop pieces and save free pawn now after this non logical move)

6..e3 human theory lines

6.  Nc3 Stockfish line

Both leads to regain pawn plus development plus centre control whereas black should not allow those at move 3...... dxc4 .

So, 3......dxc4 inaccuracy 

6......Bf4?? Blunder. White ended up significant disadvantage since move 6.

Telling 3...dxc4 is an innacuracy is just laughable...

It is a main line till ages.

4.a4 is not the critical move (a3 and e4 are the ones), leading to many choices for black : Nf6, e6, Bf5, Bg4, Be6, b5.

Each of these moves have to be studied (need some work...) : giving an engine some seconds/minutes is certainly not enough to assess an opening.

Plans with b5 are usually unsound but there are exceptions, probably not here though.

There is no reason for black to play b5 after white pushed a4...

There are many main lines that are useless in these days.

If you were old school, you will not notice. 

1. e4 e5 2. f4 is the mainline (king gambit) but leads to massive inferior position for white

2. d4 Nf6 2. c4 e5 is mainline of Budapest.

. Keep your mainline and play. I wanna see how your result will end up against your peers.

There are also tons of inferior  book lines that leads to inferior position too. 

Saying that 3.dxc4 is theorically an inaccuracy make sense to me. I am going to explain why I am thinking that.

Blacks played 2.c6 holding the center on move two then they go against their own idea one move later on move three by giving the center with 3.dxc4 and it's already weird. It's like a queen gambit accepted (QGA) with a Nf3 for whites and a pawn on c6 for blacks. I don't belive it helped blacks more than whites. Usually to equalize the center in the QGA blacks play c7-c5 in one move but here you would lose one tempo because of c7-c6 then c6-c5. If you go for b7-b5 to use the c6 pawn it leads to an inferior triangle system :

1) 3.e3; b5 4.a4; e6 5.ab; cb 6.b3; Bb4+ 7.Bd2; Bxd2+ 8.Nbxd2; a5 9.bxc4; b4 10.Ne5; Nf6 11.Be2! (Bf3); Bb7 11.Qa4+!; Nbd7 12.c5; OO 13.c6; Nb6 14.cxb7; Nxa4 15.bxa8; Qxa8 16.Rxa4; Qxg2 17.Bf3; Qh3 18.Rxa5 +-

2) 3.e3; Be6 4.Nbd2; b5 5.a4; Qa5 6.Be2; Nf6 7.O-O; g6 8.Ng5; Bd5 9.e4; h6 10.exd5; hxg5 11.dxc6; Nxc6 12.axb5!; Qxa1 13.bxc6; c3 14.bxc3; Qxc3 15.Qa4 +-

The normal QGA with 2.dxc4 and then c7-c5 later in one move or the triangle system 3.e6 4.Nc3; dxc4 5.e3; b5 6.a4; Bb4 7.Bd2; a5 seem more natural and logical. In practice playing this way can surprise an opponent and work for multiple reasons but, in my opinion (rather the opinion of the computer which I believe in), not because of the inherent strenght of this opening / move order. 

u are telling semi slav is bad only because some analysis (in a bad way) with an engine and some thoughts by a 1900 player?

Come on guys, a bit of humility maybe?

I've never played it as black, but top players used to play it since decades.

But sure if u make the moves u want to play for black (because u don't know theory or didn't search a bit) and to crush them, continue this way.

https://www.chessgames.com/perl/chessgame?gid=1372960

https://www.chessgames.com/perl/chessgame?gid=1362401

It is easier if you can find the game at chessgames. Click on the PGN view option. Copy the PGN thing. Go to the thread where you want to post the game. Click on the chessboard symbol at the far left above the box where you enter comments. Click on the Load PGN option. Paste the PGN thing into the box. Click on the Load option. Click on the Insert option. (I think it is good manners to paste a link indicating where the PGN thing was found.) Click on the Post option.

Did you miss checking the move order or are you sure your grandpa's old book from 20th Century is still good?

Come on, I read ECO 500 lines in my teenage. QGA D20 to D29 lines will highlight. 

1. d4 d5 2.dxc4 or similar lines,

The main idea of QGA lines mainly encourage

e6 or  a6 or Nf6 very early. 

The game OP mentioned is wrong.

Black did QGA after doing 2......c6 and then 3.....dxc4. 3.... dxc4 is played 1000+ games vs 48000 Nf6 or 5000 e6.

1000+ must be sidelines, not mainline.

At move 3.. Black should do either 3.... e6 or 3.... Nf6.

https://www.365chess.com/game.php?gid=4199281