Question are there any core 2 quad series that still could run heavy task like gaming and others?

You won't be able to game, but multitasking can be okay with enough ram and fast enough other components--ssd, gpu, etc.

Depending on what motherboard you have, the q9650 is the holy grail of lga775 quad cores, and the e8600 is a very fast dual core. The others in the same series q9xxx and e8xxx can be found for substantially cheaper than the top dogs.