GMod screen ratio too small

[Zarail]

I recently got a new PC monitor, and the first thing I did was try it with Squad, which worked perfectly.
Then I tried it on Garry's Mod, and I got a pair of black bars at the right and left sides of the screen. Obviously, I tried changing the aspect ratio (which did jack shit) as well as the resolution. I tried all of it, but none of those settings seemed to have fixed it.
I also checked my screen settings, and its not there either. I only find this problem in Garry's Mod.

Is there a way to fix this, or is my screen "too big"? I'm not good with computers so I have no idea.

 

[Hosterss]

Play around with these in your launch options see if anything helps.

• 
  

  [*]-w <width> - Forces the engine to start with resolution set to <width>.
  [*]-h <height> - Forces the engine to start with resolution set to <height>.

 

[Zarail]

Play around with these in your launch options see if anything helps.

where can i find these launch options? Like mentioned before, I am bad with computers, and I haven't toyed around with GMod settings in a while.

 

[Hosterss]

Right-click Gmod in you steam library and hit properties. First button out of the two should be launch options.

 

[Zarail]

Right-click Gmod in you steam library and hit properties. First button out of the two should be launch options.

I keep trying with different numbers but nothing changes.

 

[Hosterss]

Try going into nvidia control panel and experiment there. The thing is that neither you or I know how you work that program so :/.