If the manufacturer and model that you given was printed on your main board and you are sure that it is a DFI AK75-EC board then this model is listed at the bottom of this page:
http://www.dfi.com/product/productlist.asp which Soupy already pointed you to. This page is part of DFI, the manufacturer's, website.
By using the hyperlinks you can get to firstly a list of specifications of the board, which is a good idea to check against what you've actually got to be double sure, and then you get to a page listing available BIOS updates. Since you mention rev a. you have to look closely at the page before downloading anything as one column demonstrates that different BIOS updates are applicable to different rev. boards under the AK75-EC model.
Depending on what startup errors you are getting the board could be faulty - I'm not sure if I would feel comfortable flashing through a BIOS if I thought I had a faulty board.