.... and there are 4 of them on a motherboard.
Why 4? Not 8?
There's an end somwhere. In real world it will be power or price before performance. Why? Performance scales lineary, power and price does not...
As I said, ratios counts most. If you hit power limits in performane/power ratio then you can do nothing. If you change that ratio to 6/2 then you can increase performane 3 times...