$250 i7 5820K vs. i7 6700k

[timn123]

Earlier today I spotted an ad on my local classifieds which was an i7 5820k processor for $250. According to the seller, it's only been used for 3 months. He's willing to throw in a mobo (Asus X99) + 16gb (PNY Anarchy) ram for a grand total of $450. I made a list of parts on PCPartPicker with the new i7 6700k, new mobo and 16gb ram which totals about $520. I'm wondering if I'm getting a good deal on this because I know that the 5820k uses a completely different socket than the 6700k. I'm wondering if it could seriously harm possible upgrade paths because it's an older CPU. At the same time, the 6700k barely outperforms the 5820k by about 5% lol. An extra 5% doesn't seem like a $70 difference to me. Any suggestions? New parts or the 5820k? Thanks for your help in advance!

Edit: Using the CPU for rendering, Photoshop, and gaming (1440p with a GTX 1080)

 

[hdgaming]

hmm, though in full use the i7 5820k will be the stronger processor. Personally I never like second hand stuff, never know what happened to it, though I sell my pc parts second hand aswell and I never did anything wrong with it. It's just my personal feeling on that.

Personally I would get the i7 6700k new, both options will be good for the task you want to do though so follow your own feelings here.

 

[timn123]

Thanks for the reply! I'm usually on the same side - second hand stuff is always kind of a gamble.