Sorted my cables and now everything burns. SEND HELP!

[Mr.Tabasco]

This is my second try on writing this, because the forum logged me out and I lost the whole post. Today is just not my day.
First of all thanks to everyone who takes the time reading this and trying to help me.

So, yesterday everything was fine. Faf ran like a champ, I had dual screens set up (via the normal second adapter option within the game. Apparently people say it is not working, but it did for me. At least until now), and I was a happy little commander.

Then I sorted my cables, unplugged my monitors while doing that, and now everything is broken.

To give you a rough overview: (Yes I got rid of all mods)

My FPS are abysmal. If I put all video-options to the lowest possible level, I get 60fps when zoomed in the max with only one unit on the field.
Putting only fidelity to medium will reduce this to 18 fps max.
I think it has something to do with the resolution, because when I go into window mode, I can influence the FPS heavily by resizing the window. I get nearly 10 frames when I stretch it over both screens. Isn't that great?

Not that important, but maybe worth taking a note: My previous working dual screen setup stopped. My second monitor ignores now the settings for the secondary adapter, but my main screen will change its resolution to something around 800x450 when I put anything in there. It will also keep that in any later game I start until I disable the adapter again.

I don't even know where to beginn.
My specs are:

Win 10 (64)
Intel i7-2600K (I did not overclock it) @3.40GHz 3.70GHz
16GB Ram ddr3
Geforce 580

Good old supcom. I can record battlefield 3 on 50fps on high graphics, but my computer becomes a potato once I join this game.

A little edit:
I just made my secondary monitor (an old TV) my main and started the game on it. It looks horrible, butu I have way better fps. What the heck is going on?

[nine2]

I had an experience like that.
not all HDMI cables are the same
not all adapters are the same

In my case I had a slow setup on my tv where I had HDMI out of video card into tv. i changed it to use displayport mini with a good HDMI adapter and good hdmi cable, it fixed it.

You say battlefield works at 50fps but does it work on either monitor

[Mr.Tabasco]

That is a good question. It did on the old monitor, which is a VGA cable put into a DVIadapter connected to my graphiccard (I know, but it works!). That is now my secondary monitor (on which the game runs quite nicely). My new main monitor is connected via HDMI. You think this is the culprit? Should I get a different cable? Basically, what can I do, if this is it?

[nine2]

put the cables back the old way to prove that this fixes it.
then you can start isolating which bit exactly is the problem and what u want to do about it.

[coffeejoshua]

Mr.Tabasco,

Were you using the HDMI cable before you "sorted" them?

Are you sure your HDMI is plugged directly into your GPU (with the others) and not directly into the motherboard (which uses your integrated graphics on your CPU)? This is a classic mistake, as the cable will fit in either slot, but you'll suffer a horribly performance loss if you use the integrated graphics.