System will need to be running to update the BIOS.
Have you checked the NewEgg customer comments to see if anyone else tried a i5-3570K and got it to work without a BIOS upgrade?
Have you thought about changing your motherboard order to a Z77 model?
i would suggest using a cheap compatible CPU just to upgrade the BIOS then turn off the computer return the CPU or use that CPU in another computer which it is also compatible with putting the Ivy Bridge CPU into it next before installing the OS as the OS might need another software license if you change out the hardware which you are installing it upon especially if you change out the CPU but that all depends on whether or not you are planning on a reinstall in the future which is all possible.
seems like a lot of trouble for something thats only slightly slightly better.
I think the I5-2500k would be more than enough and it'll suffice. I heard its overclock capabilities are really good too.
Thanks everyone for helping.