Hey man! That really helped! I averaged 96 fps now. That's really weird that the OC degraded the performance like it did by like 30% I guess I just wont overclock and leave it as is hah.
Weird things can happen when overclocking. You are taking your hardware past the recommended settings. It can cause settings to get stuck, stuff in the OS to change. It's just one thing you have to live with if you're going to overclock. The biggest thing is to keep an eye on your temps. If it becomes unstable or behaves oddly after you make a change, as long as your temps didn't spike to 120C or something like that, it's unlikely you'll damage your hardware. Hardware is pretty resilient as long as you don't overheat it for extended periods of time.
With your overclock you know something isn't right at 120MHz and you said you were jumping it 30MHz at a time, so your last stable was 90MHZ. You could try 100MHz. However from what I read, nVidia cards throttle at 80C, so you were loosing performance because the GPU hit it's thermal limit and lowered it's clock rate. I think the thermal limit can be changed to allow it to go above 80C. The other option if you can stand some additional noise is to change the fan profile to spin the fan up quicker before it hits 80C.
That or just be happy with it at default.