If your plan in the QGD exchange variation is to play for the minority attack, then what is wrong with cxd4? In the QGD exhange variation black will have to play c6 to give protection to the d5 pawn. After d4-d5 c4-e6 Nf3-c6 after cxd4-exd4 it will be the same position eventually, or does black have a better option?
What to do against the annoying Triangle/Noteboom move order?

There are lots of ideas that white can play, but either the marshall or noteboom will probably win lots of games at your level if you can play them well as white.
Also consider this line, black has to be super prepared to survive.

If I play 4. Nf3 for a Noteboom, my opponents can still play 4...Nf6 anyway and go into a normal Semi-Slav.

You've got a few options. No matter what, you will have to deal with some level of discomfort:
Option 1 - Deal with the Noteboom - 4.Nf3 dxc4
Option 2 - Deal with the Marshall Gambit - 4.e4 dxe4
Option 3 - Deal with the Exchange Slav - After 4.cxd5, Black can take back with EITHER pawn. He is committed to the variations of the exchange Slav that involve an early ...e6, so no ...Bf5 lines, but it's different than your normal Slav as you don't play the exchange variation based on what you are saying, if he goes that route.
Option 4 - Alter your opening move order via 1.c4 or 1.Nf3. In the case of 1.c4, you do have to deal with the Symmetrical and Reverse Sicilian lines, and can transpose to d4 openings against the Indian Defenses. Against 1...e6 or 1...c6, you can go Reti if you hate the slav lines (1.c4 c6 2.Nf3 d5 3.g3 (or 3.b3, which is more passive), but the downside is that if you go 1.Nf3 d5 2.c4 e6 or 1.c4 e6 2.Nf3 d5, then after 3.cxd5 exd5 4.d4, you are committed to lines with Nf3 and lose the option at Nge2. Also, after 1.Nf3, instead of the reverse sicilian, you have certain Reti lines to deal with or else 1.Nf3 d5 2.d4 (Kramnik did this) with certain other nuances.
I can tell you that in my case, in the past, I also played the 4.Qc2 lines of the Slav, but I didn't play the Exchange QGD. The two lines don't mesh. Instead, it was typically a Catalan that I played against ...e6 lines, and with ...c6 played as well, you specifically have the Closed Catalan. Wojo's Weapons takes this approach.

@ThrillerFan This is a very useful and informative post. Here are my thoughts:
If I play 4. cxd5, I am not too concerned about entering an exchange Slav because I do figure to have some advantage by being able to develop my bishop more actively than my opponent, which is not possible in a normal exchange Slav where both sides develop symmetrically. What I am concerned about is 4...exd5 because then black can develop his bishop more actively than he could in a normal Q.G.D.E. The statistics in my database seem to indicate that neither side has any advantage, and in some lines, black is even scoring slightly better at master level. But I do think that I know how to play in that pawn structure, and the general ideas of that position, better than most of the people I would be playing, and so maybe it doesn't matter that it isn't the most active way to play. I don't know.
As for a different move order, I don't think I would want to learn theory of Nf3 or c4 lines that don't transpose into d4 lines, although I have previously considered playing 1. c4 and playing the Botvinnik against 1...c5 and 1...e5. I don't think that'll be my choice, though.

I should probably learn something better than 4. cxd5. I was just playing around with it against a computer and I was not happy with the positions I was getting.

@ThrillerFan This is a very useful and informative post. Here are my thoughts:
If I play 4. cxd5, I am not too concerned about entering an exchange Slav because I do figure to have some advantage by being able to develop my bishop more actively than my opponent, which is not possible in a normal exchange Slav where both sides develop symmetrically. What I am concerned about is 4...exd5 because then black can develop his bishop more actively than he could in a normal Q.G.D.E. The statistics in my database seem to indicate that neither side has any advantage, and in some lines, black is even scoring slightly better at master level. But I do think that I know how to play in that pawn structure, and the general ideas of that position, better than most of the people I would be playing, and so maybe it doesn't matter that it isn't the most active way to play. I don't know.
As for a different move order, I don't think I would want to learn theory of Nf3 or c4 lines that don't transpose into d4 lines, although I have previously considered playing 1. c4 and playing the Botvinnik against 1...c5 and 1...e5. I don't think that'll be my choice, though.
Personally, I think 4.cxd5 is the weakest of the 4 options, and that you should either learn the Noteboom, Marshall Gambit, or Catalan.
That said, the line you mentioned shouldn't be too much of a concern I don't think, unless I'm missing something.
In the Exchange QGD, which line do you play (via normal move order)? After 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.cxd5 exd5 5.Bg5 c6! (Black's best move if you ask me), do you play 6.e3 or 6.Qc2?
If you play the former, Black has the line where he accepts doubled pawns to get his Bishop active, namely 6.e3 Bf5 7.Qf3! (All other moves give White nothing) Bg6 8.Bxf6 Qxf6 9.Qxf6 gxf6.
In the case of the latter, 6.Qc2, you have to deal with ...Nh5 lines, which can be tricky.
If you want to play the lines you are talking about against the Slav, I would recommend the Catalan against ...e6 lines.
Otherwise, a line that worked well for me when I was a 1.d4 player against the QGD was the Rubinstein Variation, namely 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Bg5 Be7 5.e3 O-O 6.Nf3 and now if 6...h6 you can play 7.Bxf6 if you want to avoid the Tartakower and Lasker Variations, and if 6...Nbd7, instead of 7.Rc1, give 7.Qc2 a whirl. Typical rules of thumb here are if Black plays 7...c5, answer with 8.Rd1. If not 7...c5 (many amateurs play 7...c6?!), then Castle Queenside. If Black plays h6 with his King already castled, always look out for h4 possibilities. If he takes the Bishop, when you take back with the pawn, he has to return the Knight unless he can go to e4 with the Knight, but usually that area is dangerous. Anything else, like ...Ne8, leads to Qh7#. The Light Squared Bishop almost never goes to d3 in these lines. It either stays home at f1, or in the case of Queenside Castling, it can go to e2 to allow the d1-Rook to swing to g1 or h1.
I've won some nasty games with this variation. I'd have to fetch those games, but I remember one where I got my pawn to g7 and was mating Black while he spends time fianchettoing the Light-Squared Bishop and playing ...c5 - ...cxd4 - ...dxc3 (You can have that Knight, I'm mating you on the other side of the board!)

@ThrillerFan against 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. cxd5 exd5 5. Bg5 c6 I play 6. Qc2. I have never faced
Nh5, so I'll have to look into that.
I'm leaning towards 4. Nf3 and playing into a Noteboom or Semi-Slav. But the 5. Bg5 lines do seem a bit tricky still after 5...dxc4. Or I might play 4. e3, since that seems to be more solid.

@ThrillerFan against 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. cxd5 exd5 5. Bg5 c6 I play 6. Qc2. I have never faced
Nh5, so I'll have to look into that.
I'm leaning towards 4. Nf3 and playing into a Noteboom or Semi-Slav. But the 5. Bg5 lines do seem a bit tricky still after 5...dxc4. Or I might play 4. e3, since that seems to be more solid.
Keep in mind, it's not 6.Qc2 Nh5 immediately, the main line of the Nh5 idea goes 6.Qc2 Be7 7.e3 Nbd7 8.Bd3 Nh5

When you find the answer come back and tell me Chess players have been trying to answer this question for 30 years.

Ever consider the accelerated exchange 3.cxd5? It has its flaws, but should get you into comfortable positions if you prefer the minority attack, because black never gets the chance to play c6--it should transpose into exactly the opening you wanted at worst. Of course, you still have to deal with the Slav move order 2.c6...

But assuming you specifically want to pursue the strategy of the minority attack, it's probably not going to happen against the Slav. The Slav Exchange is pretty drawish for sure.

I would suggest playing 4. e3 White has a few good ways ways to play against a semislav transposition after that. And if they play the stonewall with f5 since you havent played nf3 you can go g4 with interesting play.

In recent games white has been scoring very well in the exchange slav. Maybe black can eventually equalize, but white can press for a long time with no risk, and always has the more pleasant position. I would rather play the white side of the exchange slav than the white side of the berlin, for sure.

The Exchange Slav exchanges a single pair of pawns. If you go to your favorite database, plug in the starting position of the Exchange Slav, and filter out all games decided in under 20 moves, you will find that the Exchange variation is a very dangerous beast with many decisive games!
The main problem with the Exchange Slav is its reputation. Some masters will play the Exchange Slav as a tacit draw offer. Once you remove those games where two masters were just filling out the forms, you will see that the better player usually wins in the Exchange variation.
Trading off a single set of pawns is not enough to draw the game. If you play the Exchange Slav to win, you'll have a full-blooded game on your hands!
1. d4 d5 2. c4 e6 3. Nc3 c6
I love playing the Q.G.D. Exchange for white. The minority attack of b4-b5 is a simple but effective plan which wins me a lot of games against players at my level (I am rated U.S.C.F. 1496). To play the Q.G.D.E., I have to play 3. Nc3 against 2...e6, but this leads to an uncomfortable situation for me when my opponent plays 3...c6 instead of 3...Nf6. I really don't know what to do in that position. In the normal Slav move order (1. d4 d5 2. c4 c6 3. Nf3 e6 or 3...Nf6), I like to play 4. Qc2, but this obviously doesn't do anything against the Triangle move order because of the Nc3. I also can't play 1. d4 d5 2. c4 e6 3. Nc3 c6 4. Qb3 unless I want to give my opponent a good game, because after 4...dxc4 5. Qxc4 b5 6. Qd3 b4, my opponent is kicking my pieces around and will soon tempo the queen again with ...Ba6 and I will be in a sorry state. There are four options I can seriously consider in this position:
-4. e3 leads to a Meran or some other normal Semi-Slav, which I am not too fond of playing for white. These types of positions are why I like to play 4. Qc2 in the other move order, because I'm not always that comfortable in this variation and I feel that black just has way too much play for my liking. I'm not entirely confident of the plans that each side is playing for in this variation either: I know white has to play e4, and black has to play ...c5 or ...e5, but in practice as white I have not always been confident continuing into these middlegames all the time. Maybe if I knew more about this variation I would be more okay with this. In addition, black can also play 4...f5 and be really annoying, taking me into a Dutch where I've played the passive move e3. Maybe it isn't so bad but it sure looks like a good transposition for black!
-4. Nf3 leads to the Noteboom, or a mainline Semi-Slav. I don't think I like the Noteboom that much for white, since I don't like giving my opponents connected passed pawns on my queenside, but at any rate if black wants, he can play 4...Nf6 instead and now we have another Meran or other Semi-Slav.
-4. e4 leads to the Marshall Gambit, which I don't think suits my style at all, and doesn't seem good for white. I don't really get the gambit, but I do feel that I wish to be proven wrong about this one since I figure this is something with the potential to win me a lot of games at my level. But right now it seems to me (and I probably have no idea) like a gambit where black, with best play, is fine, and also white has to memorize a ton of stuff, which I am not always fond of doing.
-4. cxd5 is the option I am maybe seriously considering the most. I know that black is probably equal after 4...exd5 because he doesn't have to worry about tricks against his d5 pawn and thus can develop his bishop more actively than in the normal Q.G.D.E., but I like playing these positions so much for white in the Q.G.D.E. that I almost want to play this anyway. But is this really what it comes to? I don't want to play an opening where I know my opponent has easy equality and just hope he doesn't find it, and I'm not sure I should be sacrificing accurate play and the possibility of an opening advantage for a position that I like with a simple plan. But at my level, will it really matter?
I want the input of stronger players who play this stuff as either white or black. Obviously I don't know a lot about these lines, but they all seem annoying and I want to know which one I should play. Thanks for reading and answering.