I am currently using a Intel i7 - 2600K CPU - LGA 1155 for gaming, photoshop and video editing.

I just GOT a Fatal1ty X79 motherboard as a gift. This is an LGA 2011 socket so I need a new CPU.

My situation is that I have limited money, so I need and LGA 2011 CPU that is better performer then the 2600K, but I don't think I can spend more then $300-$400.

What do you think is my best choice?

I see the Intel CORE i7-3820 - 3.6GHz is around $300 and the Intel Xeon E5-2620 - 2.0GHz is around $400, which is better?

How much better is the 3820 vs. 2600K? Hi there hankfarkas

The 3820 has some improvements over the 2600k, such as more cache and it supports 4 channels of DDR3 1600 memory (the 2600k supports dual channel DDR3 1066/1333).
One disadvantage of the 3820 is that it doesn't come with a heatsink/fan - definitely not a deal breaker and this may not even be a problem if you use aftermarket CPU cooling.
The 3820 doesn't have integrated graphics like the 2600k does, but with this nice of a CPU/Motherboard and your gaming, photoshop, and video editing it would be best for you to use a dedicated graphics card ANYWAY. As for the Xeon E5-2620, It is a newer and better CPU, with more cache and 6 cores as apposed to the 3820's 4 cores. Despite this I would personally go for the 3820, as its cheaper and will have plenty of muscle for your applications.

Here is a link to newegg comparing the newer 3820 to  your current 2600k:
HTTP://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=-1&IsNodeId=1&Description=intel%202600k&bop=And&CompareItemList=-1|19-115-229^19-115-229-TS%2C19-115-070^19-115-070-TS

Mike


Short answer. The improvements are not revolutionary. They are evolutionary.  They are incremental and will have little impact on what you really do. Who told you to get a new CPU?