Tf2 and any other game @fullscreen, can only run the same resolution@refreshrate that windows(?) allows on the desktop.
You could just add to the EDID your resolution and refreshrate.
This might be of use. I used a program called CRU that created an entirely new EDID for the edited monitor...
If you have nvidia, you can rather use the driver software to create a new resolution.
Be aware that editing the EDID may damage your hardware, depending on the values!!!
This is 'overclocking' a monitor.
I think this goes into hardware?