You reinstalled windows and all the drivers and stuff when you changed HDD right?
Have you tried rolling back to older drivers or updating to newer ones?
Its a 1gb card so have you monitored the GPU memory usage?
Ur ram and CPU are just fine no bottleneck there. Hdd just effects loading times. And ur temps are borderline amazing so ur good there too. The only hardware thing it could be is that 1gb memory on the GPU. I may be all wrong, and I think I am, but that could be doing it. Most likely its software related