ATI 38xx BIOS editor (Finally!)

[Jon Boy Deluxe]

How have you flashed your HD3870X2?
AtiWinFlash doesn't load for me, it just puts my CPU under stress and makes my mouse laggy. (Hidden stress test? )
I have read the bios files with GPU-Z, but i'm afraid of flashing before i know how it at least _should_ work.

I have this problem too

Edit: I scrapped using atiwinflash.
I made a bootable usb stick like this and just put atiflash and the modded bioses on and did it in dos...