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.
I have an older 3xxx card as well and enabling DPM noticeably reduced work temperatures. I'd say the temperature levels with DPM enabled are similar to using fglrx propriety drivers.
I have tried and it helped a bit in that the fan doesn't seem like it will take off, but temperature wise not that much of a difference.
At least it's not shutting down, it's staying at around 66 degrees when idle.
My setup is also slightly more complicated because this laptop has hybrid graphics (basically 2 radeon cards), in this case turning off switcheroo helped a bit as well.
The lessons this laptop taught me:
- don't buy ATI/AMD
- don't buy hybrid/dual graphics
I'm very pleased with my other laptop with a Sandy Bridge CPU and integrated Intel grahics HD3000.