BPI-M3 compile Opencv 3.1.0 source code

So you believe every BS you find somewhere on the web? GPU is wrong there, MHz are wrong, GFLOPS are wrong.

Look into the datasheet http://linux-sunxi.org/A83T#Documentation and look for Antutu 3D scores of A83T equipped devices. GPU clockspeed will be reduced brutally since A83T is always overheating:

Did you ever tried this out? Just do some GPU intensive stuff and watch dmesg output: GPU clock will be reduced even with mild workloads.