We are going to start with the basics. Please read the OP of the following thread including all of the "Spoilers". If you do not understand the basics and what exactly you are changing or trying to change then you risk completely screwing up and bricking your GPU.
http://www.overclock.net/t/1561372/hawaii-bios-editing-290-290x-295x2-390-390x/0_20Please feel free to look through other threads here like Eliovp's thread after you have read the above info. It will quickly become apparent to you that there are a lot of people that do not understand the basics and therefore are unable to get the results they wish.
I would recommend that you read ALL of the info even if it seems like you will not use it because it may explain a procedure that you may use later. Some of the things to really pay attention to are the following:
1 - VID, DPM, EVV
2 - VDDC, VDDCI
3 - Offsets
4 - Learn to use AtomBios, a Hex Editor
5 - Learn what ASIC Quality means and the Leakage
Please do not try and flash a ROM if you are not 100% sure of what you are doing.
I am willing to answer questions about modding roms and help you mod roms. PLEASE ask the questions on the thread and NOT by PM so others can learn from the questions. I am asking you to do this out of respect for those that have put in tons of time on the threads on overclock.net and because that is the way they do it and it seems to work well.
I ask you to be respectful on this thread and please do not spam the guys with PM's here or on Overclock.net.
Lastly, I am not interested in directly making ROM's for people. If you are looking for someone to hire there are several people that are for hire that do a great job.
Thanks