I've actually done something similar. I bought an OEM ASUS P8-Z68-V PRO off ebay and then replaced the bios chip with one flashed with the retail bios for the P8-Z68-V PRO and it worked without issue. Sometimes the OEM version of a motherboard is the same as the retail one but with a more locked-down bios. ASUS actually does this a lot, but if and if you compare the board layout and markings to stock pictures you can generally tell.
I'm not sure about your model, because I've never seen one, but if you're willing to take the risk it might very well work. You can generally get a bios chip off of ebay or get your current chip reflashed to the retail bios if you know anyone with an eeprom programmer. You cannot use the flash software program because the OEM bios and Retail bios claim not to be compatible (even if they are).
You can find the bios chip using the diagram in the manual for your motherboard, and they can easily be removed by an IC remover or if you don't have one you can use a very small flathead screwdriver but you must be very careful. make sure the system is totally off when you do this. If the replaced chip doesn't work, you can just pop the old one back on and it will most likely still work. Make sure to line the chip up correctly because they only go in one way, generally they have one slightly shorter pin to help line them up.