i wanted to getIntel Desktop Board Media Series LGA 1155 DDR 1333 Micro-ATX Form Factor - BOXDH67BLB3 from amazon for my gen 3 cpu, i was wondering if its bios was updated so i can use a gen 3 i5 on it.
Without knowing the pedigree of the board, there is no guarantee that the BIOS on the board is at or past the point where support for 3rd generation processors is present.
There are no new Intel desktop motherboards as Intel exited the desktop board market years ago.
The board you are looking is more than six years old:
https://ark.intel.com/products/50098/Intel-Desktop-Board-DH67BL Intel® Desktop Board DH67BL Product Specifications
It may be NOS (new old stock). There is no way to know what bios it has unless you look at specific information on the box or board.
If you get the board, you can update the bios:
https://downloadcenter.intel.com/download/22273/BIOS-Update-BLH6710H-86A-?product=50098 Download BIOS Update [BLH6710H.86A]
As for purchasing the board, I would make certain there is a return policy.
Better yet, purchase a current board: Check manufacturers like ASUS, EVGA, MSI, etc.