On my old laptop, an HP G61 something, I had a Mobility 4200. I hadn't been able to test it with the released 3.11 (replaced it before it was out), but I did always add the patches from the drm-next branch that was developing all of this. It did make a decent change in the temperature of the whole laptop. From being about 60C down to about 40C if I remember right. At least when I wasn't trying to run minecraft.