7990 and 7970 matrix

[Bazippy]

So i was going to sell my 7970 matrix,but started tinkering with the idea of keeping and crossfiring it with the 7990.
Okay i know my cpu will bottle neck but doesnt matter at the moment! Ill be using it for gaming lots and hashing when not gaming!
Here is the problem the 7970 matrix plat did not mine well infact only ever reaching 520mhash now ive seen the 280x versions hash at 720khash so id only keep if i could get this to work so id flash the bios on the 7970(never done that but im sure some reading will help)
So is this a good plan? any issues with this setup?the thing that worries me is the asus could only be controlled well with gpu tweak(which i hated) but that was the only software that could get both fans to 100%
Im hoping i can use gputweak on the asus and afterburner on the 7990?
ps yes i have enough space and yes my psu has run both these cards together at once before.

 

[Bazippy]

tried everything,lots of advice taken from elsewhere and still was getting terrible hash rate. Ive read certain matrix cards just dont mine!
So i think flashing it is the best way and to get a 280x for no extra cost just sounds cool.
I know im bottlenecked technically but 120fps in bf4 isnt exactly upsetting so adding the matrix for mining use only doesnt seem a bad idea really!

 

[Bazippy]

What bios should i flash to my matrix? 280x matrix? any help pointing me towards them - Also does this mean i need to install the 280x drivers aswell as my normal 7990 drivers?
Just flashed my 7990 with the custom bios first to get things nice and sorted with that,bit daunted by flashing the matrix and trifireing it!