Do you mean potential hashing power? Because transistor count and hashing power are not directly correlated, as noted by the 2billion transistors of RV870 monstrously crushing fermis 3billion transistors in hashing power.

I have found this chart interesting.

difficulty by itself really has no meaning for a miner.
USD:BTC by itself likewise really has no meaning.

What matter is price & difficulty.   
If price of BTC falls 90% and difficulty falls 90% I will make the same amount (in USD).
Likewise if price of BTC rises 500% and difficulty rises 500% I will still make the same amount (in USD).

Till now I haven't seen a good way to express that important relationship.

http://bitcoinx.com/charts/

This chart illustrates it well (showing daily revenue in dollars per 100MHash/s).


Long term we would expect this trend to fall continually because the cost to produce 100MHash/s rig continually falls (faster and cheaper GPU due to Moore's law).


Great chart by the author (although I think changing the unit to GH/s might be more applicable today).

FYI, this is what it says on the PSU:



Thats "only" 1320W on 12V lines, which is all that GPU's use.

Even at stock speeds (edit) 300Wx3 + 375W = 1275W for the GPU's alone. Granted, thats TDP, while mining at low memory speeds it might be lower than that, but you have other devices that need 12V, not in the least the CPU.