I have had my L521x for several weeks now and have Precise running well for the most part. Screen is beautiful and style is nice. Even got used to the way the track pad works (two finger right click and scrolling, miss middle mouse button though).

All was going well until I tried to push the graphics capabilities of the video cards by running MineCraft. It ran well for a little while. The NVidia fan spinning along until the app just stopped.

I killed minecraft several times and started it up again. Still it would crash. I even ran minecraft using the Intel video card (I just didn't run the app using $ optirun from bumble bee). That work some but it got really hot.

CPU reported 90 - 100 decree Celsius temp so I stopped using it and went back to my tried and true Latitude 6420. (It's an ugly case but damn thing works)

So I'm hoping someone has some thoughts to keeping the CPU and NVidia chips cooler. My one thought is the drivers are not throttling the gpu and it's just running full tilt. Or there is just a design flaw with this new laptop.

SPECS:

Hardware: Dell XPS 15 (L521x)
CPU: i7-3520M
Memory: 8GB
HD: 512GB SSD
GPU: NVIDIA® GeForce® GT 640M with 2GB GDDR5 VRAM

OS: Ubuntu Precise Pangolin (12.04.1)
Kernel: Latest Stable (sorry I'll have to look it up again.)