Any advice how to keep my 290 stay under 75 c ?
coolaboratory liquid pro 
or
coolaboratory liquid metal pad (for cpu 38*38mm) - it`s enough one pad to cut for 4 gpus
Is it proven to be better than the average paste/pad or is it just marketing ?
I know from experience that even a shit thermal paste give good result when you change from old paste.
clp,clu is a good paste but hard to remove after.Also you should be very careful when applying and it eats aluminum.