Just an observation:
1. If you assume a RX 480 does about 30Mh/s, then it takes roughly 33 cards to make 1 GigaHash
2. 1000 GigaHash is about 33,000 video cards
3. Network hash rate has went from 16,000 to 20,000
4. Therefore we have added about 4 x 33,000 or 132,000 cards to the network over the last month
Does that sound right? That's a lot of new video cards.
Network Difficulty is spiking to 307 TH today according to etherscan.io . It was 298 TH yesterday.