i never tried matrix under LN2 but i think matrix and lightning are easy to clock if u have good thermal paste, the new VGAs for Xtreme OC are not fun, Hipro5 mods FTW, old days
Hack firmware start vgpu 1.50 vpll 1.30 and 1.90 vmem is good for a lot of cards i think + OCP and PWM mod(short the points) use the +- on the card and go to over +1.65 (easy and best way)
mod OCP+ PWM + Mem (just short points) use GPUtweak special version
for them all u need MSI XE if u want go over 1600MHz core(easier i think)