Im Looking for a rig for 3D (not complexity model, building only by sketch up), Vray rendering(CPU) and lights photoshop process workstation, budget around 4k

Im looking 4cores 8 Threads (i7 6700 or i7 4790 or Xeon)
compatible economic graphic card, as my modeling is simple which currently able to be handled by my laptop (AMD HD6300m)

Thanks in advance.