I have an MSI GT70 with an i7-3610QM @ 2.3 GHz, 12gb RAM and a geforce 660M with 3Gb RAM, and I'm very happy with it. What I really like for rendering is the turbo fan button, you can turn the fan on high for rendering and don't have any concerns with the system overheating (good cooling is really important for rendering on laptops). The 3Gb graphics card is great as well.

The only thing I don't like about it is the dual graphics card set up. It has an imbeded intel 4000 graphics card, and the 670M, and uses both. In most situations this is fine, but for GPU rendering with Lux it causes some system stbility issues. It works, you just can't use anything that need OpenGL when using GPU rendering (plus you get a temporary dirver crash, but not a big issue).

I've used laptops more than desktops for 3D. You won't get the same performance as if you were to spend the same amount on a desktop, but for me, the added convinience of being able to work virtually anywhere is well worth the trade off in potential performance. The turbo fan on the MSI has been great!!! I've run renders for over 24 hours, and don't have to worry about overheating.

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