Engadget has stumbled upon a rather interesting Dell listing, which includes two new mobile quad-cores.

The Core i7-840QM runs at 1.86GHz and 3.06GHz on Turbo. It's around 10 percent faster than the previous 820QM, which is clocked at 1.73GHz. However, it will be around $65 pricier than the 820QM.

The Core i7-740QM is clocked at 1.73GHz, but thanks to Turbo it can deliver up to 2.93GHz. It should replace the 1.6GHz Core i7-720QM, but it will be a few bucks cheaper than its predecessor.

Mind you, AMD has recently introduced two mobile Phenom II quad-core parts, clocked at 1.6GHz and 2.0GHz. As usual, AMD's chips are quite a bit cheaper than Intel's and if you're looking for an affordable quad-core notebook they definitely are worth looking into.

More here.