This is not true. A31/A31s used SGX544MP2, A83T contains only SGX544MP1 (half that fast) and you can’t use OpenCL ‘out of the box’ anyway. Just read through the forums of responsible vendors that used these GPUs in their SoCs to get the idea (TI or NXP for example).
Everthing that’s written in datasheets or marketing material regarding BPi M3 is either irrelevant or wrong
But that’s the problem with Banana Pi M3. A beefy product when looking at specs. But can you run it with all CPU cores busy at top speed? No. Does it matter whether GPU clock speed is specified above 600 MHz? No since everytime you would need the performance CPU cores get killed and/or throttle down and the same applies to the GPU (since it’s just one core with 4 shaders here only throttling applies since you can’t kill the only core).
The whole board is a design flaw. A HUGE heatsink is the most basic requirement for A83T! But since they do not test their stuff under normal conditions they do not even know (or did you ever see a single picture of any BPi M3 made by @sinovoip where A83T has a heatsink? They simply don’t care at all about performance)