Well, my starter kit (high cost per hash, but no VAT: 18.0182 BTC to be exactly) made a little over 7.1 BTC by now and I'm just gradually overclocking over the months while getting comfortable with it.

Just 11 BTC to go in the coming 5 years or so, running around 62 GH at the moment. In this time span it's only possible with around 6% average growth in difficulty per 2160 blocks.

Now the applied voltage and the voltage regulator seem the main bottlenecks for approaching the theoretical 5 GH per chip. A small selection of chips do or don't hash on a irregular basis.

Is the voltage regulator alone replaceable (if RF02 is replaced like a board designer pointed out) and what could be the following bottleneck?